Biosurfactants: properties and applications in drug delivery, biotechnology and ecotoxicology

bioengineering Review Biosurfactants: Properties and Applications in Drug Delivery, Biotechnology and Ecotoxicology Thiago R. Bjerk 1,†, Patricia Severino 1,2,† , Sona Jain 1, Conrado Marques 1,2, Amélia M. Silva 3,4 , Tatiana Pashirova 5and Eliana B. Souto 6,7,*   Citation: Bjerk, T.R.; Severino, P.; Jain, S.; Marques, C.; Silva, A.M.; Pashirova, T.; Souto, E.B. Biosurfactants: Properties and Applications in Drug Delivery, Biotechnology and Ecotoxicology. Bioengineering 2021,8, 115. https://doi.org/10.3390/ bioengineering8080115 Academic Editor: Juana Mendenhall Received: 27 July 2021 Accepted: 11 August 2021 Published: 13 August 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1Institute of Technology and Research (ITP), Av. Murilo Dantas 300, Aracaju 49010-390, Brazil; [email protected] (T.R.B.); [email protected] (P.S.); [email protected] (S.J.); [email protected] (C.M.) 2Industrial Biotechnology Program, University of Tiradentes (UNIT), Av. Murilo Dantas 300, Aracaju 49032-490, Brazil 3Department of Biology and Environment, School of Life Sciences and Environment, University of Trás-os-Montes and Alto Douro (UTAD), 5001-801 Vila Real, Portugal; [email protected] 4Centre for Research and Technology of Agro-Environmental and Biological Sciences (CITAB), University of Trás-os-Montes and Alto Douro (UTAD), 5001-801 Vila Real, Portugal 5Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of Russian Academy of Sciences, Arbuzov St. 8, 420088 Kazan, Russia; [email protected]u 6CEB—Centre of Biological Engineering, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal 7Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal *Correspondence: [email protected] † Authors with equal contribution. Abstract: Surfactants are amphiphilic compounds having hydrophilic and hydrophobic moieties in their structure. They can be of synthetic or of microbial origin, obtained respectively from chemical synthesis or from microorganisms’ activity. A new generation of ecofriendly surfactant molecules or biobased surfactants is increasingly growing, attributed to their versatility of applications. Surfactants can be used as drug delivery systems for a range of molecules given their capacity to create micelles which can promote the encapsulation of bioactives of pharmaceutical interest; besides, these assemblies can also show antimicrobial properties. The advantages of biosurfactants include their high biodegradability profile, low risk of toxicity, production from renewable sources, functionality under extreme pH and temperature conditions, and long-term physicochemical stability. The application potential of these types of polymers is related to their properties enabling them to be processed by emulsification, separation, solubilization, surface (interfacial) tension, and adsorption for the production of a range of drug delivery systems. Biosurfactants have been employed as a drug delivery system to improve the bioavailability of a good number of drugs that exhibit low aqueous solubility. The great potential of these molecules is related to their auto assembly and emulsification capacity. Biosurfactants produced from bacteria are of particular interest due to their antibacterial, antifungal, and antiviral properties with therapeutic and biomedical potential. In this review, we discuss recent advances and perspectives of biosurfactants with antimicrobial properties and how they can be used as structures to develop semisolid hydrogels for drug delivery, in environmental bioremediation, in biotechnology for the reduction of production costs and also their ecotoxicological impact as pesticide alternative. Keywords: bioengineering; biosurfactants; antimicrobials; drug delivery; polymeric matrices; hydrogels 1. Introduction Surfactants are an important class of chemical compounds widely used in various sectors of modern industry [ 1 – 3 ]. The world market is projected to reach USD 52.4 billion Bioengineering 2021,8, 115. https://doi.org/10.3390/bioengineering8080115 https://www.mdpi.com/journal/bioengineering Bioengineering 2021,8, 115 2 of 18 by 2025, and it is estimated that the demand for surfactants will increase at a rate of 35% per year. This fact is substantiated in the growing population through growing awareness about the products such as hand sanitizer and anti-inflammatory and emulsification properties due to COVID-19 pandemics [4]. Surfactants are amphiphilic molecules composed of hydrophilic and hydrophobic portions in the same molecule. Surfactants are categorized according to their origin as of synthetic or microbial nature, obtained either from chemical synthesis or produced by microorganisms, respectively. Synthetic surfactants used in various industries, such as the pharmaceutical, medical, agriculture, environmental remediation, and oil industries, have a detrimental role in the environment [5,6]. A concern to look for new alternatives, focusing on ecofriendly [ 7 ] and biobased polymeric surfactants [ 8 ], is increasingly growing, while biodegradability and sustainability are requirements that led to the development of technologies involving microbial sources. In addition to high biodegradability, they should also be environmentally safe and easily produced. Surfactants obtained from microbial sources also are called biosurfactants. The academic and industrial interest in biosurfactants has increased in recent years due to their diversity, environmentally friendly character, and the possibility of production by fermentation. Additional advantages include their biodegradability, low toxicity, production from renewable sources, functionality under extreme pH and temperature conditions, and stability. These properties enable biosurfactants to be used in emulsification, separation, and solubilization, to reduce surface/interfacial tension and to promote adsorption of bioactives through biological membranes [9,10]. Bacteria, filamentous fungi, or yeast are the microorganisms commonly employed for biosurfactant production. The obtained product can be glycolipids, phospholipids, lipopeptides, fatty acids, saponins, and alkyl polyglycosides. The lipophilic groups can be a protein or a peptide, with hydrophobic parts composed of carbon chains of 10 to 18 carbons or fatty acids. The hydrophilic groups can be amino acids, monosaccharides, disaccharides, or polysaccharides. All biosurfactants under different conditions and other systems show the ability to reduce the surface/interfacial tension of oil/water mixtures [11]. Biosurfactants produced by bacteria are of particular interest due to their antibacterial, antifungal, and antiviral properties with therapeutic and biomedical potential [ 12 ]. Their production generally uses pathogenic bacterial species, such as Pseudomonas and Bacillus, which may be considered a disadvantage attributed to their toxicological risk, requiring the handling of strains in a biosafe environment [ 11 ]. Recently, literature has described the use of yeast-like fungi, including Starmerella bombicola, and non-pathogenic bacteria such as sophorolipids belonging to the genus Candida bombicola, to overcome these identified risks [13]. Biosurfactants with lower molecular weight (e.g., glycolipids and low-molecularweight lipopeptides (LPs) and phospholipids) show industrial potential because of their capacity in reducing surface and interfacial tension. Among glycolipids, those that have a greater interest are trehalolipids, cellobiose lipids, mannosylerythritol lipids, rhamnolipids (derived mostly from Pseudomonas), and sophorolipids (SLs) (derived from Candida and related species) [ 14 ]. Besides, the potential therapeutic uses attributed to these biosurfactants with high molecular weight (such as polysaccharides, lipoproteins, or lipopolysaccharides) include their surface adherence and emulsifier properties. The antibacterial properties of glycolipids and rhamnolipids are attributed to their permeabilization effect that compromises the integrity of the bacterial plasma membrane. This affects cell surface charge and alters hydrophobicity in a manner similar to the action of synthetic cationic surfactants. They can also make bacteria more susceptible to antimicrobial agents, as they can prevent the formation of biofilms [15]. Sophorolipids produced by yeast show great industrial interest. The molecule consists of the disaccharide, a sophorose, linked to a long chain of hydroxyl fatty chain through a glycosidic bond consisting of hydrophobic characteristics that provide biocidal, cytotoxic, and pro-inflammatory activities, with potential applications in the food, cosmetics, and Bioengineering 2021,8, 115 3 of 18 bioremediation industries [ 16 ]. It has been reported that sophorolipid has the capacity to form amphotericin B-loaded niosomal formulation with unique structural characteristics and physicochemical properties, as well as biofilm-breaking functionality and activity [ 17 ]. Lipopeptides (LPs) are composed of lipid portions linked to a peptide chain and are also reported to have biological activities, including antimicrobial properties. The most characterized LPs are daptomycin [ 18 ] and polymyxin B [ 19 – 21 ], lipopeptides microbially derived from antibiotics that have been used in the development of drug delivery systems. Surfactin (SUR), iturin, and fengicin are also among the most well-known LPs and have many potential applications. They accumulate at interfaces showing different polarities, especially oil/water and air/water, and they act as wetting agents on solid surfaces (water/solid). This dynamic process is based on the ability of biosurfactants to reduce surface tension through the placement of their amphiphilic parts in specific areas of the membrane or surface in between the phases. The antimicrobial mechanism is assumed to be LPs polymerization to form transmembrane channels in cells. The antimicrobial activity of biosurfactants is generally quite sensitive to any significant structural change. Chemical synthesis taking into account structure-activity relationships will allow the development of new amphiphiles with improved pharmacological properties, bioavailability, and consequent biodegradability [ 10 , 22 ]. This review summarizes the recent advances and perspectives of biosurfactants, their production from different sources, their physicochemical characterization, and their application as antimicrobial agents, in environmental bioremediation, in pharmaceutics as drug delivery systems, in biotechnology, in the reduction of production costs, and also their ecotoxicological impact. 2. Production and Physicochemical Characterization 2.1. Synthesis of Biosurfactants of Microbial Origin Biosurfactants can be obtained from microorganisms’ activity (such as from Pseudomonas and Bacillus), through enzyme-substrate reactions and fermentation processes, as well as being synthesized extracellularly using biocatalyst enzymes. Both the hydrophobic portion and the hydrophilic portion of the biosurfactants can be synthesized in two independent pathways: both the portions can be substrate-dependent, or one can be synthesized de novo while the other is induced by the substrate [23]. 2.1.1. Glycolipid Biosurfactants Glycolipids are the most common type of biosurfactants. Some of the common glycolipid biosurfactants such as rhamnolipids, trehalolipids, sophorolipids, and mannosylerythritol lipids (MELs) contain mono and disaccharides combined with long-chain aliphatic acids or hydroxy-aliphatic acids [24]. Rhamnolipids are one of the most important glycolipids and are known for their excellent physicochemical properties [ 23 , 24 ]. Rhamnolipids are mainly produced by Pseudomonas and Burkholderia species. The first step in the production of rhamnolipids includes synthesis of the sugar part containing rhamnose from D-glucose, and the hydrophobic acid part from fatty acids [ 25 ]. The enzymes necessary for this first step are usually found in most bacteria, but the specific enzymes needed for the biosynthesis of the rhamnolipids are found almost exclusively in P. aeruginosa and Burkholderia species. Five different enzymes, RhlA, RhlB, RhlC, RhlG, and RhlI, have been reported to be associated with the production of rhamnolipids in P. aeruginosa [26]. Microbial fermentation can result in different kinds of rhamnolipids. Mono-rhamnolipids and di-rhamnolipids differ in the number of rhamnose groups present in the molecular structure. Rhamnolipids also differ with respect to chain length, degree of branching, and degree of unsaturation in the fatty acid chains, all dependent on the environmental and growth conditions [ 27 ]. About 60 different rhamnolipid congeners and homologues have been reported [ 28 ], using a combination of Pseudomonas and other bacterial species. Many Burkholderia species have been shown to produce longer alkyl chain rhamnolipids compared to those produced by P. aeruginosa [ 29 ]. Different substrates, such as alkenes, citrates, Bioengineering 2021,8, 115 4 of 18 glucose, fructose, and olive oil, have also been employed for producing biosurfactants with different properties [27]. A number of studies have been carried out to disclose the best way to produce rhamnolipids, both in terms of safety and cost effectiveness. Engineering P. aeruginosa to reduce its pathogenicity is one such way, while another approach involves the expression of the key genes responsible for rhamnolipid production in non-pathogenic strains [ 30 ]. The cost of producing rhamnolipids can be reduced by selecting suitable substrates, such as vegetable oils, and optimizing the fermentation process [ 31 ]. Sophorolipids can be produced by several non-pathogenic yeast species, genus Candida being the most common, and C. bombicola and C. apicola (containing enzymes necessary for the terminal oxidation of alkanes to generate fatty acids) are the most used species [ 32 ]. Sophorolipids can be found in two different forms, the lactonic and the acidic form. Like rhamnolipids, the cost of production of sophorolipids (compared to chemically synthesized surfactants) is very high, which limits their industrial production [ 33 ]. Use of oil byproducts or food waste has been suggested as an alternative to reduce the production costs [34]. 2.1.2. Lipopeptide Biosurfactants The biosynthesis of surfactin occurs through a non-ribosomal mechanism catalyzed by surfactin synthetase, a protein complex comprising four enzymatic subunits, among which the subunit SrfD is crucial to initiate the synthesis [ 35 ]. Other lipopeptide biosurfactants, such as iturin, lichenysin, and arthrofactin, are also produced by similar synthase complexes [36]. Bacillus subtilis is the main bacteria utilized for surfactin production. Genetic engineering of the wild-type strain to improve the low yield has been reported. Wu et al. (2019) modified 53 different genes in B. subtilis to reach a yield of around 42% of the theoretical yield [ 37 ]. Apart from normal fermentation, surfactin can also be produced through solid state fermentation (SSF), a process in which microorganisms grow on or inside solid substrates or supports, in the absence of free water. Lipopeptide biosurfactants have also been reported to be produced by Pseudomonas aeruginosa using renewable resources, such as lubricating oil and peanut oil [38]. 2.1.3. High-Molecular-Weight Biosurfactants/Bio-Emulsifiers Bio-emulsifiers (BE) are high-molecular-weight compounds produced by bacteria, yeast, and fungi. They are synthesized as complex mixtures of heteropolysaccharides, lipopolysaccharides, lipoproteins, and proteins which can be adhered to the cell surface or released [ 39 ]. Bio-emulsifiers show a wide variety of physicochemical properties granted by different microbes that produce them [ 23 ]. Acinetobacter spp. is among the earliest known members producing BEs. Emulsan and Alasan are the best examples of the commercially used bio-emulsifiers produced by Acinetobacter spp [ 40 ]. Emulsan is a lipoheteropolysaccharide polymer containing D-galactose-amine produced during the stationary phase. Maximum concentration is obtained when culture media containing 12 carbon-based fatty acids are used as the carbon source. Emulsan production is possible with fermentation methods such as batch, chemo-stat, immobilized cell system, and self-cycling fermentation. Other bio-emulsifiers such as mannoprotein have been reported to be produced within the cellular wall of Saccharomyces spp. and Kluyveromyces marxianus and are released from the cell wall of yeast using pressurized heat treatments [41]. 2.2. Physicochemical Characterization Microorganisms are able to produce a wide variety of similar biosurfactants, but with a different bioactivity. In addition to their source, the physicochemical characteristics of these biosurfactants are influenced by production and purification processes. Understanding of these characteristics is important for the correct indication of their industrial application [ 23 ]. This section elucidates some important properties of biosurfactants, instrumental for their use as emulsifiers. Bioengineering 2021,8, 115 5 of 18 2.2.1. Surface and Interfacial Tension An important feature of a bio-emulsifier is its ability to reduce surface and interfacial tension. This is an essential function of amphiphilic molecules for the formation of kinetically stabilized emulsions. These molecules adsorb on interfaces (air/liquid, liquid/liquid, solid/liquid), replacing water or oil molecules along the interface and reducing intermolecular forces between solvent molecules and surface or interfacial tension [ 23 , 24 ]. Compared to chemical surfactants, biosurfactants were able to decrease the interfacial tension more efficiently [ 42 ]. Surfactin is one of the most active surface biosurfactants. Surfactin displays an expressive surface activity from 72 mN/m to 27 ± 2 mN/m [ 43 ] and interfacial tension to 3.79 ± 0.27 mN/m and 0.32 ± 0.02 mN/m under harsh physical and chemical conditions [ 44 ]. A lipopeptide biosurfactin called arthrofactin produced by Arthrobacter sp. strain MIS38 [ 45 ] and biosurfactant produced by Candida lipolytica UCP 0988 [ 46 ] showed low surface activity. Such unique surface properties are associated with the more complex chemical structure of biosurfactants. Unlike synthetic surfactants, they do not have a clear distribution of polarity, and also contain branched or ring structures [ 47 ]. Lipopeptide surfactin is capable of forming spherical structures to facilitate close packing at interfaces and the formation of structures with a low aggregation number [ 48 ]. Unusual surface properties of saponins have been observed. Their behavior was explained by a dense molecular packing at the interface of phases and a strong hydrogen bond between saccharide groups in the interfacial layer [ 49 ]. The very compact surface layers formed are denser than those observed in most common amphiphiles. The aforementioned properties of biosurfactants determine their binding mechanisms to biomolecules and cell membranes. A more detailed comparison of properties, namely, surface activity and critical micellization concentration (CMC) values, is presented in the review [ 50 ]. In some cases, low CMC values and surface activity can be associated with the presence of impurities in surfactant compositions. 2.2.2. Self-Assembly Micellization is a balancing process, resulting in thermodynamically stable nanostructures. Surfactants spontaneously form micelles in aqueous solvents at concentrations above the CMC [ 51 ]. Figure 1shows the relationship between surfactant concentration and surface tension. After reaching the CMC, the surfactant monomers are grouped in micelles [ 52 ]. Biosurfactants have a tendency to spontaneously self-assemble through hydrophobic effect and weak Van der Waals interactions. The effectiveness of the biosurfactant is defined by its ability to reduce surface tension. The surface tension of the water is 72 mN/m; a good biosurfactant can reduce this value to 30 mN/m [ 53 ]. The size or shape of the micelle depends on changes in the concentration of biosurfactant, temperature, pH, pressure, and salts, among others. The repulsive forces of the head groups restrict the amount of associated biosurfactants in the formation of micelles [ 23 ]. Increasing the surfactant concentration above the CMC value favors the formation of a greater number of micelles. The formation of micelles with a low aggregation number is characteristic of both rhamnolipids and surfactin. Then, they can be reorganized into bubble structures [ 54 ]. While temperature was shown to barely affect surface activity of surfactants, rhamnolipids were transformed into vesicles upon the increase of temperature and decrease of pH [ 55 ]. Micelle formation of biosurfactants depends both on the structure of the hydrocarbon chain and on the peptide sequence. The hydrogen bonds between the head groups of biosurfactants lead to the formation of supramolecular structures with different morphologies [ 56 ]. The architecture of nanostructures formed by biosurfactants can be nanotubes, spiral, twisted cylindrical nanofibers, and others [57]. Bioengineering 2021,8, 115 6 of 18 Bioengineering 2021, 8, 115 6 of 18 structure of the hydrocarbon chain and on the peptide sequence. The hydrogen bonds between the head groups of biosurfactants lead to the formation of supramolecular structures with different morphologies [56]. The architecture of nanostructures formed by biosurfactants can be nanotubes, spiral, twisted cylindrical nanofibers, and others [57]. Figure 1. Representation of biosurfactant action. Micelle formation after reaching critical micellar concentration. 2.2.3. Solubilization Amphiphiles self-assembled in aqueous solutions can solubilize hydrophobic compounds (oil, for example), which preferentially reside in the hydrophobic domains of the amphiphilic nanostructure. The solubility of hydrophobic organic compounds in the presence of biosurfactant depends on the concentration, pH, and the incorporation of additives and salts (electrolytes) that can change the size of micelles [58]. Rhamnolipids can increase the solubilization of hydrophobic compounds by increasing the hydrophobicity of amphiphilic molecule. Biosurfactant molecules have a tendency to form vesicles and micelles with increasing pH, which limits the solubilization of other molecules. The properties of biosurfactants are specific to the substrate, solubilizing or emulsifying different hydrocarbons at different rates [59]. Biosurfactants are more effective solubilizing agents than synthetic surfactants [60]. For example, a biosurfactant obtained from Rhodococcus erythropolis HX-2 exhibited a higher solubilization for petroleum and polycyclic aromatic hydrocarbons than synthetic surfactants sodium dodecyl sulfate (SDS), polysorbate (Tween 80), Triton X-100, and rhamnolipid [61]. It is interesting to note that rhamnolipids can solubilize n-alkanes not only at concentrations above CMC [62], but also below CMC [63]. Their solubilization efficiency of n-alkanes is 3–4 order higher below CMC [64]. A synergistic improvement in solubility of polycyclic aromatic hydrocarbons was observed in the case of interaction between two biosurfactants (rhamnolipid and sophorolipid) compared to one glycolipid [65]. 2.2.4. Emulsifying Action Emulsions are kinetically stabilized systems, but without balance. Its structure, stability, and appearance depend on the composition of the liquid phases (oil and water) and of emulsifier (chemical structure and physicochemical properties) and the conditions of the preparation (temperature and pressure) and the process (input energy, mixing time, and the kind of equipment) [66]. The emulsion can be broken down by several mechanisms, including skimming, flocculation coagulation (aggregation of the emulsion droplets), Ostwald maturation, and coalescence. Creaming may happen, caused by the difference in densities between oil and water phases, where the emulsion droplets miFigure 1. Representation of biosurfactant action. Micelle formation after reaching critical micellar concentration. 2.2.3. Solubilization Amphiphiles self-assembled in aqueous solutions can solubilize hydrophobic compounds (oil, for example), which preferentially reside in the hydrophobic domains of the amphiphilic nanostructure. The solubility of hydrophobic organic compounds in the presence of biosurfactant depends on the concentration, pH, and the incorporation of additives and salts (electrolytes) that can change the size of micelles [58]. Rhamnolipids can increase the solubilization of hydrophobic compounds by increasing the hydrophobicity of amphiphilic molecule. Biosurfactant molecules have a tendency to form vesicles and micelles with increasing pH, which limits the solubilization of other molecules. The properties of biosurfactants are specific to the substrate, solubilizing or emulsifying different hydrocarbons at different rates [ 59 ]. Biosurfactants are more effective solubilizing agents than synthetic surfactants [ 60 ]. For example, a biosurfactant obtained from Rhodococcus erythropolis HX-2 exhibited a higher solubilization for petroleum and polycyclic aromatic hydrocarbons than synthetic surfactants sodium dodecyl sulfate (SDS), polysorbate (Tween 80), Triton X-100, and rhamnolipid [ 61 ]. It is interesting to note that rhamnolipids can solubilize n-alkanes not only at concentrations above CMC [ 62 ], but also below CMC [ 63 ]. Their solubilization efficiency of n-alkanes is 3–4 order higher below CMC [ 64 ]. A synergistic improvement in solubility of polycyclic aromatic hydrocarbons was observed in the case of interaction between two biosurfactants (rhamnolipid and sophorolipid) compared to one glycolipid [65]. 2.2.4. Emulsifying Action Emulsions are kinetically stabilized systems, but without balance. Its structure, stability, and appearance depend on the composition of the liquid phases (oil and water) and of emulsifier (chemical structure and physicochemical properties) and the conditions of the preparation (temperature and pressure) and the process (input energy, mixing time, and the kind of equipment) [ 66 ]. The emulsion can be broken down by several mechanisms, including skimming, flocculation coagulation (aggregation of the emulsion droplets), Ostwald maturation, and coalescence. Creaming may happen, caused by the difference in densities between oil and water phases, where the emulsion droplets migrate as a function of the gravitational field, resulting in phase separation [ 23 ]. The natural emulsifier must be rapidly adsorbed on the surface of oil droplets, and thus, rapidly reduces the interfacial tension to facilitate droplet breakdown and formation of small droplets [ 67 ]. The well-known biosurfactant used as an emulsifier in the food industry is from quillaja saponin extract. The emulsifying activity of the cyclic lipopeptide pseudofactin II produced by P. fluorescens BD5 is better than synthetic surfactants Tween 20 and Triton X-100. Pseudofactin II more effectively emulsified aromatic and aliphatic hydrocarbons and some vegetable oils [ 68 ]. Rhamnolipids have a greater effect on emulsion droplet size reduction than lecithin and monoglycerides and ensure the thermal stability of emulsion [69]. Bioengineering 2021,8, 115 7 of 18 3. Applications Biosurfactants can have several applications, such as in bioremediation and in food, cosmetics, pharmaceutical, biomedicine, and nanotechnology industries. This may have advantages over their synthetic equivalents as the former are environmentally friendly. Due to their biodegradability and low toxicity, the use of biosurfactants has increased, for example, in the area of biotechnology. One of the most promising areas of application of biosurfactants is in the degradation of hydrocarbons in contaminated water and soil. They can also have a significant impact on the pharmaceutical sector as drug delivery systems [70,71]. According to the work of Marchant et al. [ 72 ] and Chakraborty et al. [ 73 ], microorganisms use a set of carbon and energy sources for growth. The combination of carbon sources with insoluble substrates favors the diffusion of the intracellular medium and the production of different substances. Moreover, depending on the nature of the carbon source in the culture medium, the synthesis of biosurfactants can be directed to one of the several metabolic pathways involved in this process [ 74 ]. In this sense, microorganisms such as bacteria, yeasts, and some filamentous fungi are capable of producing biosurfactants with different molecular structures and surface activities [75,76]. Table 1shows some of the different residues that have already been used for the production of biosurfactants. Thus, it is possible to observe that several renewable sources and agro-industrial residues containing an excellent source of carbohydrates and lipids can be used as rich sources of carbon and nitrogen for the growth of microorganisms to obtain biosurfactants, in addition to contributing directly to the reduction of the environmental impact caused by these residues [77]. Some examples of residues used for the production of biosurfactants include whey and cheese, animal fat, molasses, glycerol, macerated liquor, residues from the production of olive oil and other extracted vegetable oils, wastewater from cassava processing, and potato, among others [ 42 , 78 ]. Biosurfactants comprise a group of amphipathic molecules with different chemical structures, which are produced by several microorganisms [ 79 ]. Besides, these substances, generated mainly from secondary metabolites, play fundamental roles in the survival of their producing microorganisms, contributing in turn to the transport of nutrients and the interactions between the microorganism and the host, as well as acting as biocides [ 80 ]. Due to their recognized potential and biological nature, biosurfactants have been the target of numerous researches on their probable therapeutic applications [ 78 , 81 , 82 ]. As they are of microbial origin and demonstrate a series of interesting characteristics such as low toxicity, pH tolerance, temperature, ionic strength, biodegradability, antimicrobial activity, and emulsifying and demulsifying capacity, these polymers become of great interest in applications in food, cosmetics, and advanced bioremediation processes, including in drug delivery [83]. Table 1. Different residues used in the production of biosurfactants by different microorganisms. Waste Products Producing Microorganism Type of Biosurfactant Ref. Whey Pseudomonas aeruginosa BS2 Rhamnolipid [84,85] Bacillus spp. Lipopeptides [86] Molasses Pseudomonas aeruginosa GS3 Rhamnolipid [87] Bacillus spp. Lipopeptides [35,88] Starmerella bombicola NBRC 10243 Lipopeptides Sophorolipids [89] [13,90] Potato processing effluents and cassava wastewater Bacillus subtilis Lipopeptides [31] Frying oil Pseudomonas aeruginosa 47T2 4 Rhamnolipid [91] Corn steep liquor Aureobasidium thailandense Glycolipid [77] Candida lipolytica [46] Refinery oil waste Yeast Glycolipid [33,77,89] Bioengineering 2021,8, 115 8 of 18 These agents have several properties suitable for the food industry as emulsifiers in the processing of raw materials, indispensable for food products that require stability content, a characteristic sensory pattern, and longer shelf life, being applied from products derived from meat, milk, and their derivatives. Given their antimicrobial and anti-adhesive properties, these biosurfactants directly contribute to reducing contamination of processed foods [92]. Biosupplements are generally classified as low molecular weight such as glycolipids and lipopeptides and high-molecular-weight biosurfactants which are polysaccharides, proteins, lipoproteins, etc. Generally, low-molecular-weight biosurfactants demonstrate significant active properties due to their relatively simpler structures [ 93 , 94 ]; thus, as shown in Table 2, rhamnolipids (glycolipids) and surfactin (lipopeptide) are among the most studied biosurfactants. The study by Elshikh et al. [ 95 ] demonstrated that the effect of biosurfactants associated with antibiotics as antimicrobial agents presents interesting results. According to the researchers, the combination of nisin and rhamnolipids inhibited thermophilic spores and increased the shelf life of dairy products, while the use of natamycin with rhamnolipid also promoted increased durability of the products, inhibiting the growth of yeasts in industrialized foods. These three associated substances (nisin, natamycin, and rhamnolipids) were also evaluated in some types of cheese and it was observed that there was inhibition of the growth of bacteria and yeasts in these products as well as prolonged shelf life. These results demonstrate that rhamnolipids have anionic characters mainly due to their carboxylate groups, which, in solution, these groups tend to organize on the cell surface lipid membranes, thus increasing the negative charges and promoting the electrostatic interaction between nisin and anionic membrane, which can result in synergistic effect [ 96 ]. Table 2. Biosurfactants and their applications. Type of Biosurfactant Microorganism Application Reference Rhamnolipids Pseudomonas aeruginosa, Pseudomonas putida Bioremediation [97] Pseudomonas chlororaphis Biocontrol Agent [98] Renibacterium salmoninarum Bioremediation [99] Sophorolipids Candida bombicola, Candida apicola Emulsifier [100] Glycolipids Rhodococcus spp. Bioremediation [101] Tsukamurella sp., Arthrobacter sp. Antimicrobial agent [102,103] Manosileritritol lipids Candida antartica Anti-inflammatory secretion inhibitor and RBL-2H3 cell mediators [76] Surfactin Kurtzmanomyces sp Biomedical application [80,104] Lipopeptides Bacillus subtilis Bacterial growth inhibitionBiomedical application [105] Lichenisina Bacillus licheniformis Antimicrobial activityHemolytic and chelating agent [86] Glycolipoprotein Aspergillus niger Antimicrobial activity [106] 3.1. Biosurfactants for Environmental Bioremediation Biosurfactants are promising for environmental bioremediation activities, which include cleaning up oil spills, removing heavy metal contaminants, and treating wastewater. Microorganisms are able to metabolize oil-related compounds, allowing the elimination of hydrophobic pollutants [ 107 ]. A critical factor in the biodegradation process is the increase in hydrophobicity on the microbial cell surface caused by biosurfactants. In the biodegradation process, microorganisms use pollutants as carbon and energy sources. These break Bioengineering 2021,8, 115 9 of 18 the hydrocarbon chain, which leads to an immediate loss of amphiphilicity. Finally, the pollutants are transformed into CO2, water and minerals [23]. Biosurfactants can improve the hydrocarbon bioremediation, increasing the bioavailability of the substrate for microorganisms or interacting with the cell surface to increase its hydrophobicity, thus allowing an easier association between the hydrophobic substrates themselves and the bacterial cells [99,102]. Several studies have reported the application of microbial surfactants in the process of bioremediation of contaminated soil and wastewater. In the work developed by Patowary et al. (2018) [ 108 ], the authors describe the use of rhamnolipid obtained by Pseudomonas aeruginosa SR17 for bioremediation of soil contaminated by oil. The degradation of total petroleum hydrocarbon (TPH) in soil containing 6800 ppm and 8500 ppm TPH was evaluated. The efficiency of the rhamnolipid biosurfactant was compared with the synthetic surfactant sodium dodecyl sulfate (SDS). The soil treated with rhamnolipid showed degradation efficiency of 86.1% and 80.5%; by using synthetic surfactant, this value dropped to 70.8% and 68.1%. Sun et al. (2019) [ 109 ] reported the application of biosurfactant glycolipid produced by the strain of Pseudomonas aeruginosa S5 isolated from coking effluent for in situ remediation. The inoculation of the strain in the coke wastewater promoted the biodegradation of polycyclic aromatic hydrocarbons, reducing 44% in 15 days in the sludge. Zhou et al. (2020) [ 110 ] evaluated the effects of the addition of the lipopeptide produced by Acinetobacter sp. isolated from hydraulic fracturing flowback and produced (HF-FPW). The authors observed that inoculation of the bacterial strain in HF-FPW increased the activity and growth of Pseudomonas sp. and Rhizobium sp., known for their hydrocarbon degradation capacity, achieving a reduction of 94% and 77% for n-alkanes and polycyclic aromatic hydrocarbons in 7 days. Recently, Swati et al. (2020) [ 111 ] showed that the biosurfactant produced by the strain Pseudomonas sp. ISTPY2, isolated from the Ghazipur landfill, has a degradation efficiency of pyrene present in high concentration in the soil microcosm, reaching a removal efficiency of 94% in 10 days. Tang et al. (2018) [ 112 ] evaluated the application of rhamnolipid, saponin, and sophorolipid biosurfactants to increase the removal of heavy metals Cu, Zn, Cr, Pb, Ni, Mn, Fe, and Hg from the sludge through electrokinetic treatment. The results showed that three biosurfactants can effectively increase the removal of heavy metals from the sludge, showing chelating and binding capacity under acidic conditions. Recently, Sun et al. (2021) [ 113 ] evaluated the application of biosurfactant produced by Pseudomonas sp. CQ2 isolated from the Chongqing oilfield (China) for bioremediation of heavy metals in contaminated soil. Removal efficiency of 78.7, 65.7, and 56.9% was obtained for Cd, Cu, and Pb, respectively, values higher than those obtained using chemical surfactants. 3.2. Pharmaceutical Applications of Biosurfactants Biosurfactants can assume an immense variety of functions in the pharmaceutical industry, since they have antimicrobial, anti-adhesive, antiviral, anticancer, spermicidal, hemolytic, anti-inflammatory, and immunomodulatory activities [24,114–119]. Antimicrobial application is one of the most desired uses described in pharmaceutical literature. Surfactin has several interesting properties, including antimicrobial, antiviral, antitumor, hypocholesterolemic, anti-adhesive, insecticide, apoptotic, and hemolytic action. Among other functions, surfactin inhibits the fibrin clotting process and has antitumor activity against Ehrlich’s ascites carcinoma cells, inhibiting cyclic adenosine 3 0 , 50-monophosphate phosphodiesterase, and antifungal activities [23,82]. Among the studies, lipopeptide biosurfactants showed in vitro antimicrobial, antibiofilm, and cytotoxic effects. The biosurfactant was produced by Acinetobacter junii (AjL), exhibiting inhibition against Candida utilis and becoming a potential new drug [ 120 ]. In this way, Fernandes et al. [ 121 ] used kitchen waste oil as Wickerhamomyces anomalus CCMA 0358 substrate to produce a biosurfactant with larvicide activity, Aedes aegypti larvae. The Bioengineering 2021,8, 115 16 of 18 76. Silva, A.; Santos, P.; Silva, T.; Andrade, R.; Campos-Takaki, G. Biosurfactant production by fungi as a sustainable alternative. Arq. Inst. Biológico 2018,85, e0502017. [CrossRef] 77. Meneses, D.P.; Gudiña, E.J.; Fernandes, F.; Gonçalves, L.R.B.; Rodrigues, L.R.; Rodrigues, S. The yeast-like fungus Aureobasidium thailandense LB01 produces a new biosurfactant using olive oil mill wastewater as an inducer. Microbiol. Res. 2017 ,204, 40–47. [CrossRef] 78. Gudiña, E.J.; Teixeira, J.A.; Rodrigues, L.R. Biosurfactants Produced by Marine Microorganisms with Therapeutic Applications. Mar. Drugs 2016,14, 38. [CrossRef] 79. Marchant, R.; Banat, I.M. Microbial biosurfactants: Challenges and opportunities for future exploitation. Trends Biotechnol. 2012 , 30, 558–565. [CrossRef] 80. Chen, W.-C.; Juang, R.-S.; Wei, Y.-H. Applications of a lipopeptide biosurfactant, surfactin, produced by microorganisms. Biochem. Eng. J. 2015,103, 158–169. [CrossRef] 81. Rodrigues, L.R. Inhibition of bacterial adhesion on medical devices. Adv. Exp. Med. Biol. 2011,715, 351–367. [CrossRef] 82. Gudiña, E.J.; Rangarajan, V.; Sen, R.; Rodrigues, L.R. Potential therapeutic applications of biosurfactants. Trends Pharmacol. Sci. 2013,34, 667–675. [CrossRef] 83. Ikegami, K.; Hirose, Y.; Sakashita, H.; Maruyama, R.; Sugiyama, T. Role of polyphenol in sugarcane molasses as a nutrient for hexavalent chromium bioremediation using bacteria. Chemosphere 2020,250, 126267. [CrossRef] [PubMed] 84. Banat, I.M.; Satpute, S.K.; Cameotra, S.S.; Patil, R.; Nyayanit, N.V. Cost effective technologies and renewable substrates for biosurfactants’ production. Front. Microbiol. 2014,5, 697. [CrossRef] [PubMed] 85. Dubey, K.; Juwarkar, A. Distillery and curd whey wastes as viable alternative sources for biosurfactant production. World J. Microbiol. Biotechnol. 2001,17, 61–69. [CrossRef] 86. Gomaa, E. Antimicrobial Activity of a Biosurfactant Produced by Bacillus licheniformis Strain M104 Grown on Whey. Braz. Arch. Biol. Technol. 2013,56, 259–268. [CrossRef] 87. Patel, R.M.; Desai, A.J. Biosurfactant production by Pseudomonas aeruginosa GS3 from molasses. Lett. Appl. Microbiol. 1997 ,25, 91–94. [CrossRef] 88. Abdel-Mawgoud, A.M.; Aboulwafa, M.M.; Hassouna, N.A.H. Optimization of surfactin production by bacillus subtilis isolate BS5. Appl. Biochem. Biotechnol. 2008,150, 305–325. [CrossRef] 89. Liepins, J.; Balina, K.; Soloha, R.; Berzina, I.; Lukasa, L.K.; Dace, E. Glycolipid Biosurfactant Production from Waste Cooking Oils by Yeast: Review of Substrates, Producers and Products. Fermentation 2021,7, 136. [CrossRef] 90. Takahashi, M.; Morita, T.; Wada, K.; Hirose, N.; Fukuoka, T.; Imura, T.; Kitamoto, D. Production of sophorolipid glycolipid biosurfactants from sugarcane molasses using Starmerella bombicola NBRC 10243. J. Oleo Sci. 2011,60, 267–273. [CrossRef] 91. Haba, E.; Espuny, M.J.; Busquets, M.; Manresa, A. Screening and production of rhamnolipids by Pseudomonas aeruginosa 47T2 NCIB 40044 from waste frying oils. J. Appl. Microbiol. 2000,88, 379–387. [CrossRef] 92. Durval, I.J.B.; da Silva, I.A.; Sarubbo, L.A. Application of Microbial Biosurfactants in the Food Industry. In Microbial Biosurfactants; Springer: Berlin/Heidelberg, Germany, 2021; pp. 1–10. 93. Brück, W.M. The benefits of alpha-lactalbumin in early childhood. In Dairy in Human Health and Disease Across the Lifespan; Elsevier: Amsterdam, The Netherlands, 2017; pp. 117–126. 94. Chong, H.; Li, Q. Microbial production of rhamnolipids: Opportunities, challenges and strategies. Microb. Cell Factories 2017 ,16, 1–12. [CrossRef] 95. Elshikh, M.; Moya-Ramírez, I.; Moens, H.; Roelants, S.; Soetaert, W.; Marchant, R.; Banat, I.M. Rhamnolipids and lactonic sophorolipids: Natural antimicrobial surfactants for oral hygiene. J. Appl. Microbiol. 2017,123, 1111–1123. [CrossRef] 96. Chen, J.; Wu, Q.; Hua, Y.; Chen, J.; Zhang, H.; Wang, H. Potential applications of biosurfactant rhamnolipids in agriculture and biomedicine. Appl. Microbiol. Biotechnol. 2017,101, 8309–8319. [CrossRef] [PubMed] 97. Jadhav, J.; Dutta, S.; Kale, S.; Pratap, A. Fermentative production of rhamnolipid and purification by adsorption chromatography. Prep. Biochem. Biotechnol. 2018,48, 234–241. [CrossRef] [PubMed] 98. Jadhav, M.; Kalme, S.; Tamboli, D.; Govindwar, S. Rhamnolipid from Pseudomonas desmolyticum NCIM-2112 and its role in the degradation of Brown 3REL. J. Basic Microbiol. 2011,51, 385–396. [CrossRef] 99. Mahjoubi, M.; Cappello, S.; Souissi, Y.; Jaouani, A.; Cherif, A. Microbial Bioremediation of Petroleum Hydrocarbon–Contaminated Marine Environments. In Petroleum Science and Engineering, Mansoor Zoveidavianpoor; Zoveidavianpoor, M., Ed.; IntechOpen: London, UK, 2018. [CrossRef] 100. Solaiman, D.; Ashby, R.; Birbir, M.; Caglayan, P. Antibacterial Activity of Sophorolipids Produced by Candida bombicola on Gram-positive and Gram-negative Bacteria Isolated from Salted Hides. J. Am. Leather Chem. Assoc. 2016,111, 358–364. 101. Tripathi, M.; Garg, S.K. Dechlorination of chloroorganics, decolorization, and simultaneous bioremediation of Cr 6+ from real tannery effluent employing indigenous Bacillus cereus isolate. Environ. Sci. Pollut. Res. 2014,21, 5227–5241. [CrossRef] 102. Mnif, I.; Ellouz-Chaabouni, S.; Ghribi, D. Glycolipid Biosurfactants, Main Classes, Functional Properties and Related Potential Applications in Environmental Biotechnology. J. Polym. Environ. 2018,26, 2192–2206. [CrossRef] 103. Abdel-Mawgoud, A.M.; Stephanopoulos, G. Simple glycolipids of microbes: Chemistry, biological activity and metabolic engineering. Synth. Syst. Biotechnol. 2018,3, 3–19. [CrossRef] 104. Patel, S.; Homaei, A.; Patil, S.; Daverey, A. Microbial biosurfactants for oil spill remediation: Pitfalls and potentials. Appl. Microbiol. Biotechnol. 2019,103, 27–37. [CrossRef] Bioengineering 2021,8, 115 17 of 18 105. do Valle Gomes, M.Z.; Nitschke, M. Evaluation of rhamnolipid and surfactin to reduce the adhesion and remove biofilms of individual and mixed cultures of food pathogenic bacteria. Food Control 2012,25, 441–447. [CrossRef] 106. Ansari, A.; Pervez, S.; Javed, U.; Abro, M.I.; Nawaz, M.A.; Qader, S.A.U.; Aman, A. Characterization and interplay of bacteriocin and exopolysaccharide-mediated silver nanoparticles as an antibacterial agent. Int. J. Biol. Macromol. 2018 ,115, 643–650. [CrossRef] 107. Karlapudi, A.P.; Venkateswarulu, T.C.; Tammineedi, J.; Kanumuri, L.; Ravuru, B.K.; Dirisala, V.r.; Kodali, V.P. Role of biosurfactants in bioremediation of oil pollution—A review. Pet. 2018,4, 241–249. [CrossRef] 108. Patowary, R.; Patowary, K.; Kalita, M.C.; Deka, S. Application of biosurfactant for enhancement of bioremediation process of crude oil contaminated soil. Int. Biodeterior. Biodegrad. 2018,129, 50–60. [CrossRef] 109. Sun, S.; Wang, Y.; Zang, T.; Wei, J.; Wu, H.; Wei, C.; Qiu, G.; Li, F. A biosurfactant-producing Pseudomonas aeruginosa S5 isolated from coking wastewater and its application for bioremediation of polycyclic aromatic hydrocarbons. Bioresour. Technol. 2019 ,281, 421–428. [CrossRef] [PubMed] 110. Zhou, H.; Huang, X.; Liang, Y.; Li, Y.; Xie, Q.; Zhang, C.; You, S. Enhanced bioremediation of hydraulic fracturing flowback and produced water using an indigenous biosurfactant-producing bacteria Acinetobacter sp. Y2. Chem. Eng. J. 2020 ,397, 125348. [CrossRef] 111. Kumari, M.; Ghosh, P.; Thakur, I.S. Evaluation of a biosurfactant producing bacterial strain Pseudomonas sp. ISTPY2 for efficient pyrene degradation and landfill soil bioremediation through soil microcosm and proteomic studies. Bioresour. Technol. Rep. 2020 , 12, 100607. [CrossRef] 112. Tang, J.; He, J.; Xin, X.; Hu, H.; Liu, T. Biosurfactants enhanced heavy metals removal from sludge in the electrokinetic treatment. Chem. Eng. J. 2018,334, 2579–2592. [CrossRef] 113. Sun, W.; Zhu, B.; Yang, F.; Dai, M.; Sehar, S.; Peng, C.; Ali, I.; Naz, I. Optimization of biosurfactant production from Pseudomonas sp. CQ2 and its application for remediation of heavy metal contaminated soil. Chemosphere 2021,265, 129090. [CrossRef] 114. Mouafo, H.T.; Mbawala, A.; Tanaji, K.; Somashekar, D.; Ndjouenkeu, R. Improvement of the shelf life of raw ground goat meat by using biosurfactants produced by lactobacilli strains as biopreservatives. LWT 2020,133, 110071. [CrossRef] 115. Roy, A. A Review on the Biosurfactants: Properties, Types and its Applications. J. Fundam. Renew. Energy Appl. 2017 ,8, 1–14. [CrossRef] 116. Pashirova, T.N.; Lukashenko, S.S.; Zakharov, S.V.; Voloshina, A.D.; Zhiltsova, E.P.; Zobov, V.V.; Souto, E.B.; Zakharova, L.Y. Self-assembling systems based on quaternized derivatives of 1,4-diazabicyclo[2.2.2]octane in nutrient broth as antimicrobial agents and carriers for hydrophobic drugs. Colloids Surf. B Biointerfaces 2015,127, 266–273. [CrossRef] 117. Sajid, M.; Ahmad Khan, M.S.; Singh Cameotra, S.; Safar Al-Thubiani, A. Biosurfactants: Potential applications as immunomodulator drugs. Immunol. Lett. 2020,223, 71–77. [CrossRef] 118. Gomaa, E.Z. Antimicrobial and anti-adhesive properties of biosurfactant produced by lactobacilli isolates, biofilm formation and aggregation ability. J. Gen. Appl. Microbiol. 2013,59, 425–433. [CrossRef] 119. Fariq, A.; Yasmin, A. Production, characterization and bioactivities of biosurfactants from newly isolated strictly halophilic bacteria. Process Biochem. 2020,98, 1–10. [CrossRef] 120. Ohadi, M.; Forootanfar, H.; Dehghannoudeh, G.; Eslaminejad, T.; Ameri, A.; Shakibaie, M.; Adeli-Sardou, M. Antimicrobial, anti-biofilm, and anti-proliferative activities of lipopeptide biosurfactant produced by Acinetobacter junii B6. Microb. Pathog. 2020 , 138, 103806. [CrossRef] [PubMed] 121. de Andrade Teixeira Fernandes, N.; de Souza, A.C.; Simões, L.A.; Ferreira Dos Reis, G.M.; Souza, K.T.; Schwan, R.F.; Dias, D.R. Eco-friendly biosurfactant from Wickerhamomyces anomalus CCMA 0358 as larvicidal and antimicrobial. Microbiol. Res. 2020 , 241, 126571. [CrossRef] [PubMed] 122. Jiang, X.; Yan, X.; Gu, S.; Yang, Y.; Zhao, L.; He, X.; Chen, H.; Ge, J.; Liu, D. Biosurfactants of Lactobacillus helveticus for biodiversity inhibit the biofilm formation of Staphylococcus aureus and cell invasion. Future Microbiol. 2019 ,14, 1133–1146. [CrossRef] [PubMed] 123. Moussi, K.; Bukhamsin, A.; Hidalgo, T.; Kosel, J. Biocompatible 3D Printed Microneedles for Transdermal, Intradermal, and Percutaneous Applications. Adv. Eng. Mater. 2020,22, 1901358. [CrossRef] 124. Sandeep, L.; Rajasree, S. Biosurfactant: Pharmaceutical perspective. J. Anal. Pharm. Res. 2017,4, 15406. [CrossRef] 125. Ferreira, A.; Vecino, X.; Ferreira, D.; Cruz, J.M.; Moldes, A.B.; Rodrigues, L.R. Novel cosmetic formulations containing a biosurfactant from Lactobacillus paracasei.Colloids Surf. B Biointerfaces 2017,155, 522–529. [CrossRef] [PubMed] 126. Kurozuka, A.; Onishi, S.; Nagano, T.; Yamaguchi, K.; Suzuki, T.; Minami, H. Emulsion Polymerization with a Biosurfactant. Langmuir ACS J. Surf. Colloids 2017,33, 5814–5818. [CrossRef] 127. Das, M.; Patowary, K.; Vidya, R.; Malipeddi, H. Microemulsion synthesis of silver nanoparticles using biosurfactant extracted from Pseudomonas aeruginosa MKVIT3 strain and comparison of their antimicrobial and cytotoxic activities. IET Nanobiotechnol. 2016,10, 411–418. [CrossRef] [PubMed] 128. Ohadi, M.; Shahravan, A.; Dehghannoudeh, N.; Eslaminejad, T.; Banat, I.M.; Dehghannoudeh, G. Potential Use of Microbial Surfactant in Microemulsion Drug Delivery System: A Systematic Review. Drug Des. Devel. Ther. 2020 ,14, 541–550. [CrossRef] [PubMed] 129. Paniagua-Michel Jde, J.; Olmos-Soto, J.; Morales-Guerrero, E.R. Algal and microbial exopolysaccharides: New insights as biosurfactants and bioemulsifiers. Adv. Food Nutr. Res. 2014,73, 221–257. [CrossRef] Bioengineering 2021,8, 115 18 of 18 130. Adu, S.A.; Naughton, P.J.; Marchant, R.; Banat, I.M. Microbial Biosurfactants in Cosmetic and Personal Skincare Pharmaceutical Formulations. Pharmaceutics 2020,12, 1099. [CrossRef] [PubMed] 131. Rivera, Á.D.; Urbina, M.Á.M.; y López, V.E.L. Advances on research in the use of agro-industrial waste in biosurfactant production. World J. Microbiol. Biotechnol. 2019,35, 1–18. 132. Fox, S.L.; Bala, G.A. Production of surfactant from Bacillus subtilis ATCC 21332 using potato substrates. Bioresour. Technol. 2000 , 75, 235–240. [CrossRef] 133. Minucelli, T.; Ribeiro-Viana, R.; Borsato, D.; Andrade, G.; Cely, M.; de Oliveira, M.; Baldo, C.; Celligoi, M. Sophorolipids production by Candida bombicola ATCC 22214 and its potential application in soil bioremediation. Waste Biomass Valoriz. 2017,8, 743–753. [CrossRef] 134. Martins, P.C.; Martins, V.G. Biosurfactant production from industrial wastes with potential remove of insoluble paint. Int. Biodeterior. Biodegrad. 2018,127, 10–16. [CrossRef] 135. de Almeida, D.G.; Brasileiro, P.P.F.; Rufino, R.D.; de Luna, J.M.; Sarubbo, L.A. Production, formulation and cost estimation of a commercial biosurfactant. Biodegradation 2019,30, 191–201. 136. Ashby, R.D.; McAloon, A.J.; Solaiman, D.K.; Yee, W.C.; Reed, M. A process model for approximating the production costs of the fermentative synthesis of sophorolipids. J. Surfactants Deterg. 2013,16, 683–691. [CrossRef] 137. Md, F. Biosurfactant: Production and Application. J. Pet. Environ. Biotechnol. 2012,3, 124. [CrossRef] 138. Adetunji, A.I.; Olaniran, A.O. Production and potential biotechnological applications of microbial surfactants: An overview. Saudi J. Biol. Sci. 2021,28, 669–679. [CrossRef] 139. Chittepu, O.R. Isolation and characterization of biosurfactant producing bacteria from groundnut oil cake dumping site for the control of foodborne pathogens. Grain Oil Sci. Technol. 2019,2, 15–20. [CrossRef] 140. EK, R.; Mathew, J. Characterization of biosurfactant produced by the endophyte Burkholderia sp. WYAT7 and evaluation of its antibacterial and antibiofilm potentials. J. Biotechnol. 2020,313, 1–10. [CrossRef]