RESEARCH ARTICLE Open Access
In i o e ec pho odynamic he apy wi h
di e en s pho osensi ize s on ca iogenic
mic oo ganisms
P. So ia-Lozano
1
, Y. Gilabe e
2,3
, MP Paz-C is obal
3
, L. Pé ez-A iaga
3
, V. Lampaya-Pé ez
3
, J. Apo a
4
,
V. Pé ez-Laguna
3
, I. Ga cía-Luque
5
, MJ Re illo
1
and A. Rezus a
1,3,6*
Abs ac
Backg ound: An imic obial pho odynamic he apy has been p oposed as an al e na i e o supp ess
subgingi al species. This esul s om he balance among S ep ococcus sanguis,S ep ococcus mu ans and
Candida albicans in he den al bio ilm. No all he pho osensi ize s ha e he same pho odynamic e ec
agains he di e en mic oo ganims. The objec i e o his s udy is o compa e in i o he pho odynamic
e ec o me hylene blue (MB), ose Bengal (RB) and cu cumin (CUR) in combina ion wi h whi e ligh on he
ca iogenic mic oo ganism S. mu ans, S. sanguis and C. albicans.
Resul s: Pho odynamic he apy wi h MB, RB and CUR inhibi ed 6 log 10 he g ow h o bo h bac e ia bu a
di e en concen a ions: 0.31–0.62 μg/ml and 0.62–1.25 μg/ml RB we e needed o pho oinac i a e S. mu ans
and S. sanguis, espec i ely; 1.25–2.5 μg/ml MB o bo h species; whe eas highe CUR concen a ions (80–160 μg/ml
and 160–320 μg/ml) we e equi ed o ob ain he same educ ion in S. mu ans and S. sanguis iabili y espec i ely. The
minimal ungicidal concen a ion o MB o 5 log10 CFU educ ion (4.5 McFa land) was 80–160 μg/ml, whe eas o RB i
anged be ween 320 and 640 μg/ml. Fo CUR, e en he maximum s udied concen a ion (1280 μg/ml) did no each
ha inhibi ion. Incuba ion ime had no e ec in all expe imen s.
Conclusions: Pho odynamic he apy wi h RB, MB and CUR and whi e ligh is e ec i e in killing S. mu ans and S.
sanguis s ains, al hough MB and RB a e mo e e icien han CUR. C. albicans equi ed highe concen a ions o all
pho osensi ize s o ob ain a ungicidal e ec , being MB he mos e icien and CUR ine ec i e.
Backg ound
The human o al ca i y is colonized by a highly di e se
communi y o bac e ia [1]. Den al ca ies is a ch onic, in-
asi e disease in ol ing demine aliza ion o he oo h
ollowed by des uc ion o he o ganic phase o he
den ine [2] and i is he consequence o he in e ac ion
be ween o al mic o lo a, die , den i ion and o al en i -
onmen [3].
S ep ococci a e he main colonize s o o al su aces
and cons i u e 70 % o he cul i able bac e ia exis ing in
he human den al plaque [4]. In ac , S. mu ans is he
mos p e alen mic oo ganism o he plaque and he
p ima y pa hogenic agen esponsible o ca ies disease
[5], whe eas S. sanguis is hough o play a benign, i no
a bene icial, ole in he o al ca i y [6]. On he o he
hand, C. albicans is a commensal ungal species com-
monly colonizing human mucosal su aces [7]. False a
e al. [8] hypo hesize ha S. mu ans-C. albicans associ-
a ion may enhance S. mu ans in ec ion and modula e
he de elopmen o hype i ulen bio ilms on oo h su -
aces, which will in u n in luence he onse and se e i y
o den al ca ies in i o. Fo his eason, S. mu ans,S.
sanguis and C. albicans should be included in any s udy
abou human den al plaque mic oo ganisms.
Pho odynamic he apy (PDT) has been ad oca ed as an
al e na i e o an imic obial agen s o supp ess subgingi al
species [9] due o he ex ensi e and inapp op ia e use o
an imic obial agen s which g adually led o he de elop-
men o pe asi e esis ance [10]. An imic obial PDT
* Co espondence: [email p o ec ed]
1
Depa men o Mic obiology, Hospi al Uni e si a io Miguel Se e , Za agoza,
Spain
3
Heal h Science Ins i u e o A agón, Za agoza, Spain
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So ia-Lozano e al. BMC Mic obiology (2015) 15:187
DOI 10.1186/s12866-015-0524-3
(aPDT) is a echnique ha u ilizes eac i e oxygen species
(ROS) p oduced by non- oxic dye o pho osensi ize (PS)
molecules in he p esence o low in ensi y isible ligh o
kill mammalian o mic obial cells [11]. Due o his mech-
anism, I is hypo hesized ha bac e ia will no be easily
able o de elop esis ance o PDT [12].
Mo e han 400 compounds wi h pho osensi izing
p ope ies a e known, including dyes, d ugs, chemicals
and many na u al subs ances [13]. Me hylene blue
(MB), a well-known dye wi h high ligh abso p ion a
665 nm, is e ec i e in aPDT, showing abili y o kill no
only G am posi i e and G am nega i e bac e ia bu
also ungi [14–17]. Rose Bengal (RB) is a xan hene dye
cha ac e ized by ligh abso p ion a wa eleng hs (λ)o
450–600 nm, used o he diagnosis o eye diseases
[18]. F om an an imic obial poin o iew, RB has
shown a good p o ile o pho oinac i a e mic oo gan-
isms [19–22]. Cu cumin (CUR) is an in ensely yellow
pigmen , isola ed om hizomes o Cu cuma longa,
wi h a peak o ligh abso p ion a 430 nm [23]. Among
i s many biological ac i i ies a e i s an i-ca cinogenic,
an ioxidan , an iin lamma o y, an imic obial p ope ies
and i s hypoglycemic e ec s in humans [24, 25]. Some
s udies ha e shown i s capaci y o e ec i ely pho oi-
nac i a e in i o C. albicans [26, 27].
The e a e many pape s explo ing he aPDT e ec o
di e en pho osensi ize s (PSs) in almos all kind o mi-
c obial species [28–31]. Howe e , only ew o hem com-
pa e he e icacy o se e al pho osensi ize s on di e en
mic oo ganism [32].
The aim o his s udy was o compa e he pho oinac i-
a ion e ec o h ee PSs, MB, RB and CUR, on S.
mu ans,S. sanguis and C. albicans.
Resul s
Pho oinac i a ion o bac e ial suspensions
Unde he expe imen al condi ions, PDT wi h MB, RB
and CUR inhibi ed 6 log10 he g ow h o bo h s ains
o bac e ia eaching a bac e icidal e ec . Howe e , less
concen a ion o RB han o he o he PSs was needed
o kill S ep ococcus spp. Whe eas his bac e icidal e -
ec was achie ed o S. mu ans wi h a concen a ion o
RB as low as 0.31–0.62 μg/ml, highe MB concen a ion
(1.25–2.5 μg/ml) was needed o each he same educ ion.
In he case o S. sanguis, he RB and MB concen a ions
needed o ob ain he same bac e icidal e ec we e qui e
simila o hose used o S.mu ans (0.62–1.25 μg/ml and
1.25–2.5 μg/ml, espec i ely). Much highe concen a ions
o CUR we e necessa y o ob ain he same educ ion ei-
he o S. mu ans o S. sanguis (Table 1).
Rega ding he e ec o he incuba ion ime o S ep o-
coccus cells wi h he PSs, one hou hal ed he minimal
concen a ion o MB o RB necessa y o a ain 6 log10
educ ion espec o an incuba ion ime lowe han
1 min (<1 min), especially o S. sanguis (Table 1). In he
case o CUR, his e ec was only obse ed o S. sanguis.
No signi ican addi ional bene i was achie ed using 3 h
o incuba ion (Table 1).
Compa ing he pho odynamic e ec o MB o S.
mu ans and S. sanguis suspensions, using he op imal in-
cuba ion o each PS, lowe concen a ions we e needed
o each he bac e icidal e ec o S. sanguis han o S.
mu ans (Fig. 1). Howe e , no di e ences we e obse ed
using RB as PS.
Pho oinac i a ion o C. albicans
Table 1 shows he minimum ungicidal concen a ion
(MFC) o each PS s a ing om C. albicans 4.5
McFa land. Unde he expe imen al condi ions, PDT
wi h MB, RB bu no wi h CUR inhibi ed 5 log 10
he g ow h o C. albicans, being he needed concen-
a ions o MB smalle han he RB ones (Fig. 2). An
inc ease in he incuba ion ime wi h he PS was only
bene icial o MB, because 3 h hal ed he concen a-
ion needed o each a 5 log10 educ ion in C. albi-
cans espec o sho e imes (Table 1).
Discussion
Den al ca ies may be a disease well sui ed o PDT [2].
Ou in es iga ion showed ha PDT using MB o RB and
a whi e lamp can kill ca iogenic mic oo ganisms, such
as S. mu ans,S. sanguis and C. albicans. In con as ,
e en hough PDT wi h CUR eaches he same bac e i-
cidal e ec , much highe concen a ions we e needed
and i was no e ec i e agains yeas s.
PDT e icacy depends on he mic oo ganism, he PS
and he ligh used. Acco ding o ou esul s, RB
showed highe an imic obial pho odynamic e ec o
Table 1 Minimal ange concen a ion o educe 6 log10 o S.
mu ans and S. sanguis and 5 log10 o C. albicans
P e-i adia ion
Incuba ion ime (h)
MB RB CUR
S. mu ans ATCC 35668
<1 min 1.25–2.5 μg/ml 0.31–0.62 μg/ml 80–160 μg/ml
1 h 0.62–1.25 μg/ml 0.15–0.31 μg/ml 160–320 μg/ml
3 h 0.62–1.25 μg/ml 0.31–0.62 μg/ml 160–320 μg/ml
S. sanguis ATCC 10556
<1 min 1.25–2.5 μg/ml 0.62–1.25 μg/ml 160–320 μg/ml
1 h 0.31–0.62 μg/ml 0.15–0.31 μg/ml 40–80 μg/ml
3 h 0.15–0.31 μg/ml 0.15–0.31 μg/ml 40–80 μg/ml
C. albicans ATCC 1023
<1 min 80–160 μg/ml 320–640 μg/ml >1280 μg/ml
1h 80–160 μg/ml >1280 μg/ml >1280 μg/ml
3h 40–80 μg/ml >1280 μg/ml >1280 μg/ml
I adia ion wi h me al halide lamp, λ420–700 nm, luence 37 J.cm
−2
So ia-Lozano e al. BMC Mic obiology (2015) 15:187 Page 2 o 8
S ep ococcus spp han he o he PSs s udied, whe eas
MB was be e o Candida spp. CUR always showed
he lowes an imic obial ac i i y; his could be due o
he ac ha he highe peaks o he spec um emis-
sion o he lamp co espond be e o he abso p ium
spec a o RB and MB han CUR. Table 2 shows ha
compa ed wi h p e ious s udies using aPDT wi h MB,
RB and CUR o S. mu ans, ou pa ame e s seem o be
mo e e icien , especially conside ing he pe cen age
o bac e ial g ow h inhibi ion o 99.9999 %. Rega ding
he an imic obial e ec o MB-PDT on he iabili y o
S. mu ans, A aujo e al. [33] needed 25 μg/ml MB o
each 73 % inhibi ion. Ne e heless, ou esul s a e
no comple ely compa able because hey used ed
ligh , which co esponds wi h he maximum spec um
abso bance o MB. Rega ding RB, s udies ca ied ou
by Cos a e al. [34] show ha he concen a ion
needed o a ain 6.86 log10 CFU/mL educ ion o S.
mu ans was 2.02 μg/ml, using a LED lamp wi h λ
440–460 nm and a luence o 95 J/cm
2
.Compa ing o
ou esul s hey needed highe concen a ions o PS o
each a simila e ec , pe haps because he λo hei
lampwaslesscon enien hanou s oexci eRB;an-
o he eason could be he use o dis illed wa e as dis-
sol en , whe eas hey used phospha e-bu e ed saline
because, based in he s udy o Nuñez e al. [35], a sig-
ni ican di e ence in he same aPDT expe imen can
be p omo ed only by he use o di e en s dissol en s.
Acco ding o his s udy, CUR needs much highe con-
cen a ion han RB and MB o pho oinac i a e bac e ia.
This esul ag ees wi h hose ob ained by A aujo e al.
[23] who, using a concen a ion o 1500 μg/ml and blue
LEDs lamp (λ450 nm, luence 5.7 J/cm
2
), eached 60 %
inhibi ion o S. mu ans in plank onic cul u es. Howe e ,
o he s udies ob ained 95 % educ ion o S. mu ans in-
s ead o 6 logs using only 0.73 μg/ml CUR, which could
be explained by he highe luence used (72 J/cm
2
), he λ
o he lamp (blue ligh ) and he lowe pe cen age o bac-
e icidal ac i i y ob ained.
Few s udies compa e he e icacy o di e en PSs o
pho oinac i a e o al mic oo ganisms. Rolim e al. [36]
showed ha MB, oluidine blue o ho, malachi e g een,
e y h osine, eosin and RB, using a ed LEDs lamp o
he o me and a blue one o he la e , we e pho oac i e
in i o agains S. mu ans, bu only oluidine blue e-
duced 99.9 % o he mic oo ganism. In his s udy, hey
also ind a bac e icidal e ec o RB on S. mu ans wi hou
ligh . Ne e heless, in ou s udy no an imic obial e ec s
we e obse ed when he s ains we e exposed ei he o
he dyes o he ligh sou ce sepa a ely.
Conside ing ha he ca iogenic po en ial o S. sanguis
is deemed low compa ed o ha o he S. mu ans, he
numbe o epo s using aPDT o kill S. sanguis is lowe
han hose o S. mu ans. Chan e al. [37] demons a ed
Fig. 1 Pho odynamic e ec o MB and RB on S. sanguis and S. mu ans depending on hei concen a ion (Incuba ion ime wi h he PS <1 min
and i adia ion using a me al halide lamp wi h a luence o 37 J/cm
2
)
Fig. 2 Pho odynamic e ec o MB and RB on C. albicans depending
on hei concen a ion (incuba ion ime o 1 h o MB and <1 min o
RB, and i adia ion using a me al halide lamp whi a luence
o 37 J/cm
2
)
So ia-Lozano e al. BMC Mic obiology (2015) 15:187 Page 3 o 8
ha PDT wi h MB was able o ob ain a educ ion o
99–100 % on cul u es o S. sanguis.Howe e , heyused
highe concen a ions (100 μg/ml) han we used bu
lowe luence (21.2 J/cm
2
) o a diode lase (665 nm).
Pe ei a e al. [32] only ob ained a 9.9 % inhibi ion wi h
5μg/ml RB and hey used a highe luence. The e o e,
ou esul s show MB as he mos e icien bac e icidal
PS o S. sanguis.
Acco ding o he p esen in es iga ion, MB has be e
an i ungal p o ile han RB and CUR. O he au ho s [14,
15, 38], show ha MB–aPDT is endowed wi h an i ungal
po en ial agains C. albicans, whe eas Cos a e al. [18]
show ha RB only each a 1,97 log10 educ ion in C.
albicans.
Compa ing he h ee PSs, he p esen s udy shows
ha MB is he mos e ec i e PS on C. albicans while
RB was sligh ly supe io o S. mu ans. Den al ca ies
esul om in e ac ions among di e en ca iogenic
mic oo ganisms, so using o combining di e en PSs
could imp o e he e icacy o aPDT. In his sense, he
use o a whi e ligh lamp ha co e s all he abso p ion
spec um o mos PSs can e icien ly exci e hem, mak-
ing PDT easie o pe o m and a oiding he necessi y
o using a lamp o each PS. Howe e , a ligh sou ce
wi h an emission spec um ha co esponds o he
maximum abso p ion spec um o each PS heo e ic-
ally de e mines a highe e icacy [39]. Red ligh
sou ces (630–700 nm) ha e been used ex ensi ely in
PDT due o hei ela i ely long wa eleng hs, which
can e ec i ely pene a e biological issues and ac i-
a es some o he mos e ec i e PSs, such as pheno-
hiazines and po phy ins. Addi ionally, o he s udies
ha e also shown ha blue ligh (380–520 nm) is an a -
ac i e op ion o PDT, because blue ligh sou ces can
be used in combina ion wi h many PSs, such as RB,
eosin, e y h osine, and CUR o pho oinac i a e o al
mic oo ganisms [36]. Fo his eason, one limi a ion o
ou s udy is he use o he same lamp o pho oac i a e
he h ee PSs, whose emission spec um ma ches qui e
accu a ely wi h he maximum abso p ium spec a o
RB and MB bu no wi h CUR. This could in luence
he bad esul s ob ained wi h he la e .
Acco ding o ou da a, he minimal bac e icidal o un-
gicidal concen a ion was educed in some expe imen s
wi h a p e-i adia ion incuba ion ime o 1 h. Howe e ,
conside ing ha he inc ease in he concen a ion was
only o one o wo dilu ions, he di icul y o main ain
he apeu ic concen a ions o he PS in he high low con-
di ions wi hin he o al ca i y (due o sali a and/o gingi al
c e icula luid) o a long pe iod o ime [40] do no sup-
po he use o incuba ion ime in he clinical se ing.
And ade e al. [26] using CUR and Rezus a e al. [41] wi h
hype icin concluded ha none incuba ion ime enhance
he pho oinac i a ion o plank onic cul u es o C. albicans.
Addi ionally, al hough he ad e se e ec s o blood and
sali a could be a oided wi h he help o den al dams, no
p e-incuba ion ime is mo e com o able o he pa ien s
and mo e e icien o doc o s.
Conclusions
The pho odynamic e icacy o each PS a ies acco ding
o he a ge mic oo ganism. The combina ion o di e -
en PS and whi e ligh could be a p omising app oach o
ea hose in ec ions caused by a combina ion o mic o-
o ganisms, such as ca ies.
Table 2 Summa y o he in i o PDT s udies using me hylene
blue, ose Bengal o cu cumin on S. mu ans, S. sanguis and C.
albicans
PS Concen a ion Inhibi ion λFluence
(μg/ml) (%) (nm) (J/cm
2
)
S. mu ans
A aújo e al. [33]MB25 73 ND ND
Ou s udy MB 2.5 999.999 420–700 37
Cos a e al. [34] RB 2.02 999.999 440–460 95
Ou s udy RB 0,62 999.999 420–700 37
A aújo e al. [23] CUR 1500 99.9 450 5.7
Paschoal e al. [44] CUR 1473.5 60 450 72
Manoil e al. [45] CUR 0.73 95 % 360–550 542
Ou s udy CUR 160 999.999 420–700 37
S. sanguis
Chan e al. [37] AM 100 99–100 632.8 21.2
Ou s udy AM 2.5 999.999 420–700 37
Pe ei a e al. [32] RB 5 9.9 455 95
Ou s udy RB 0.62 999.999 420–700 37
Ou s udy CUR 1500 999.999 420–700 37
Ma iello e al. [46] TB 200 84.32 660 10
C. albicans
Souza e al. [15] AM 100 99.9 660 39,5
Peloi e al. [14] 4 AM 22,5 95,14 663 6
Souza e al. [16] AM 100 88,6 685 28
Ou s udy AM 160 99.999 420–700 37
Cos a e al. [18] RB 23 9.9 455 95
Demido a e al.
[47]
RB 200 99,9999 525–555 80
Ou s udy RB >1280 <99.999 420–
700
37
And ade e al. [26] CUR 7,3 89.5 455 5,28
Do igo e al. [48] CUR 14,8 85 440–460 18
Ou s udy CUR >2460 <99.999 420–700 37
PS pho osen ize , MB me hylene blue, RB ose bengal, CUR cu cumin, TB
oluidine blue o ho, ND no da a
So ia-Lozano e al. BMC Mic obiology (2015) 15:187 Page 4 o 8
Ma e ials and me hods
Chemicals
Me hylene Blue (MB) and Cu cumin (CUR) we e pu -
chased om Sigma-Ald ich and Rose Bengal om Fluka.
Sabou aud Dex ose Aga (SB) and Columbia Blood
Aga (BA) we e pu chased om Oxoid.
Mic oo ganisms and g ow h condi ions
S. mu ans ATCC 35668, S. sanguis ATCC 10556 and C.
albicans ATCC 10231 s ains we e ob ained om he
Ame ican Type Cul u e Collec ion (ATCC; Rock ille,
MD).
McFa land scale is ecommended o pe o mance o
suscep ibili y es ing by CLSI [42] and EUCAST [43].
The yeas s we e g own ae obically o e nigh in SB
medium a 35 °C. S ock inoculum suspensions we e p e-
pa ed in dis illed wa e and adjus ed o op ical densi ies
co esponding o 4.5 McFa land o i e logs educ ion
assays. Cell iabili y was assessed coun ing he numbe
o colony- o ming uni s (CFU), de eloped on SB a e an
incuba ion pe iod o 24 h a 35 °C.
S. mu ans and S. sanguis we e g own ae obically in
BA medium a 35 °C o 48 h. S ock inoculum suspen-
sions we e p epa ed in dis illed wa e and adjus ed o
op ical densi ies co esponding o 0.5 McFa land o six
logs educ ion assays. Cell iabili y was assessed coun -
ing he numbe o CFU, de eloped on BA a e an incu-
ba ion pe iod o 48 h o S. mu ans and 24 h o S.
sanguis a 35 °C.
Pho osensi ize solu ions
S ock MB, RB and CUR solu ions we e p epa ed in dis-
illed wa e and dilu ed ei he wi h bidis illed wa e o
he desi ed concen a ion immedia ely p io o use. The
concen a ions used anged om 0.1–12800 μg/ml. All
solu ions we e p epa ed and handled unde ligh -
es ic ed condi ions.
Ligh sou ce
In o de o co e he spec um abso p ion o he 3 PSs
(Fig. 3), MB, RB and CUR (maximal abso p ion λa 665,
557 and 430 nm espec i ely), we used a me al halide
lamp emi ing a 420–700 nm (Fig. 4) wi h an i adiance
o 90 mW/cm
2
, being he speci ic i adiance a he max-
imal abso p ium λo each PS : 292 μW/cm
2
a 557 nm,
300 μW/cm
2
a 665 nm and 186 μW /cm
2
a 430 nm.
Mic oo ganisms suspensions wi h he di e en PSs p e-
pa ed in o a 96 wells mic o i e pla e, wi h a well diame e
o 6 mm, we e i adia ed o 6 min and 51 s a a dis ance
o 10 cm. The ligh beam diame e was 21 cm and he
Fig. 3 Spec um abso p ion o ose Bengal a, me hylene blue band cu cumin c
So ia-Lozano e al. BMC Mic obiology (2015) 15:187 Page 5 o 8

luence used 37 J/cm
2
. The e ec i e ligh ecei ed on he
dishes esul s om in eg a ing he powe o he lamp o
all he e ec i e wa eleng hs o each PS.
Pho odynamic ea men s o mic oo ganisms
Suspensions wi h he desi ed McFa land alue o e e y
mic oo ganism we e p epa ed in bidis illed wa e . 90 μL
o hese ini ial suspensions was d opped in o di e en
wells o a mic o i e pla e and 10 μL o he di e en PS
solu ions we e added. The inal PS concen a ion in he
expe imen s used anged om 0.01–1280 μg/ml. The
pla es we e hen main ained in he da k o di e en
pe iods o ime (<1 min, 1 and 3 h) o e alua e he in lu-
ence o con ac ime wi h he PS on he ou come o he
pho odynamic ea men s. A e wa ds, mic oo ganisms
we e subjec ed o illumina ion (37 J/cm
2
).
Fungal and bac e ial cul u es g own unde he same
condi ions wi h and wi hou PS, ei he kep in he da k
o illumina ed, se ed as con ols.
A e pho odynamic ea men s, samples and con ols
we e incuba ed a 35 °C o 24 h, in case o C. albicans
and S. sanguis expe imen s, and o 48 h in case o S.
mu ans. The an imic obial e ec was de e mined by
coun ing he numbe o CFU pe millili e.
A c i e ion o 5 log10 uni dec ease om he s a ing
inoculum was adop ed o de ine ungicidal ac i i y, and
a mo e s ingen c i e ion o 6 log10 uni o bac e icidal
ac i i y, due o he di e ences in cell size and mass be-
ween Candida spp and S ep ococcus spp ( he cell con-
cen a ion o C. albicans used was 10 imes lowe (>10
5
)
han ha used o he wo bac e ial species (>10
6
)).
All expe imen s we e ca ied ou a leas i e imes.
Abb e ia ions
MB: Me hylene blue; RB: Rose bengal; CUR: Cu cumin; CFU: Colony o ming
uni s; PDT: Pho odynamic he apy; aPDT: An imic obial pho odynamic
he apy; PS: Pho osensi ize ; SB: Sabou aud dex ose aga ; BA: Columbia
blood aga .
Compe ing in e es s
The au ho s decla e ha hey ha e no compe ing in e es s.
Au ho s’con ibu ions
PSL concei ed o he s udy, conduc ed all expe imen s and d a ed he
manusc ip . YG pa icipa ed in he design o he s udy, in he in e p e a ion o
da a o he wo k and she d a ed he manusc ip , he co e le e and he
answe s o he e iewe ’s epo s. LPA and VLP conduc ed some expe imen s
and helped o d a he manusc ip . VPL is s udying he pho odynamic e ec in
co-cul u es o C. albicans and S. mu ans and she checked ou esul s. She also
e ised he manusc ip and con ibu ed o he esolu ion o e iewe ’s epo s.
IGL has con ibu ed o he in e p e a ion o da a o he wo k and o he
esolu ion o bio ilms ques ions and in he discussion o he inal manusc ip
because she wo ks wi h us in he p ojec CTQ 2013–48767-C3-2-R om he
Spanish Minis y o Science and Inno a ion s uding he e ec o pho odynamic
he apy on bio ilms. MPPC pa icipa ed in he design o he s udy, analyzed he
da a, pe o med he Figs. 1 and 2 and he e ised he manusc ip pa icula ly he
me hodology and he ma e ials. JAA pe o med he Figs. 3 and 4 and he w o e
e e y hing ela ed ligh pa ame e s bo h in he manusc ip and in he answe s
o he e iewe ’s epo s. MJR con ibu ed o he design o he wo k, and
e ising and co ec ing i , pa icula ly he backg ound and he discussion. AR
concei ed o he s udy and d a ed he manusc ip . All au ho s ead and
app o ed he inal manusc ip .
Fig. 4 Rela i e emission cu e o he me al halide lamp
So ia-Lozano e al. BMC Mic obiology (2015) 15:187 Page 6 o 8
Acknowledgemen s
This s udy was suppo ed by g an s CTQ2013-48767-C3-2-R om he Spanish
Minis y o Science and Inno a ion, Spain and Eu opean Regional De elopmen
Fund.
Au ho de ails
1
Depa men o Mic obiology, Hospi al Uni e si a io Miguel Se e , Za agoza,
Spain.
2
Depa men o De ma ology, Hospi al San Jo ge, Huesca, Spain.
3
Heal h Science Ins i u e o A agón, Za agoza, Spain.
4
Depa men o Applied
Physics. Facul y o Science, Uni e si y o Za agoza, Za agoza, Spain.
5
Depa men o Mic obiology, Uni e si y o Se illa, Se illa, Spain.
6
Depa men o Mic obiology, Uni e si y o Za agoza, Za agoza, Spain.
Recei ed: 6 No embe 2014 Accep ed: 21 Sep embe 2015
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