*Co esponding au ho : Balbina J. Plo kin.
Copy igh © 2025 Au ho (s) e ain he copy igh o his a icle. This a icle is published unde he e ms o he C ea i e Commons A ibu ion License 4.0.
Role o sa A and ag in Insulin Modula ion o S aphylococcus au eus Bio ilm
Fo ma ion
Balbina J. Plo kin 1, *, Monika I. Konaklie a 2, and I a Siga 1
1 Depa men o Mic obiology and Immunology, Midwes e n Uni e si y, Downe s G o e, IL 60515.
2 Depa men o Chemis y, Ame ican Uni e si y, 4400 Massachuse s A e. NW, Washing on, DC, 20016-8014, USA.
Wo ld Jou nal o Biology Pha macy and Heal h Sciences, 2025, 24(01), 093-096
Publica ion his o y: Recei ed on 25 Augus 2025; e ised on 05 Oc obe 2025; accep ed on 07 Oc obe 2025
A icle DOI: h ps://doi.o g/10.30574/wjbphs.2025.24.1.0860
Abs ac
The ocus o his s udy is o de e mine whe he insulin, quo um signaling and bio ilm o ma ion a e unde egula ion o
ag and sa A egula ion. Dele ion s ains ag -, sa A -, and ag -sa A- as well as hei pa en s ain 8325-4 we e es ed wi h
and wi hou glucose (0.1% and 0.2%) and/o physiologic le els o insulin (2µU/mL, 20µU/mL, and 200µU/mL). In he
absence o sa A and ag , he e was a ma ked supp ession o bio ilm le els in he p esence o insulin, indica ing ha
insulin modula ion o bio ilm o ma ion appea s o be egula ed, in pa , by sa A and ag .
Keywo ds: Glucose; Quo um Compound; Signaling Compound; Ho mone
1. In oduc ion
The abili y o S. au eus o o m bio ilms is essen ial in i s es ablishmen and main enance o in ec ious p ocesses, e.g.,
oo ulce s in indi iduals wi h ype 2 diabe es. S. au eus bio ilm o ma ion du ing in ec ion in indi iduals wi h
uncon olled ype 2 diabe es occu s in he p esence o insulin and glucose. Bac e ial in ec ions, including su gical si e
in ec ions (SSIs), a e a common and se ious complica ion o diabe es. S aphylococcus au eus is a majo cause o SSI in
diabe ic pa ien s [1,2]. Howe e , he ole o insulin and glucose in diabe es p edisposing o s aphylococcal in ec ion is
no ully elucida ed.
Bio ilm o ma ion and s abili y a e dependen on he en i onmen . P omo ion, o inhibi ion, o bio ilm o ma ion occu s
in esponse o a ailable nu ien s, including pa hway me aboli es, quo um-signaling compounds, and he gene ic p o ile
o he o ganism [3]. Tempo al exp ession o many o he i ulence de e minan s, including bio ilm in S. au eus, is unde
he con ol o se e al gene ic loci, including ag and sa A [4-6]. The accesso y gene egula o (ag ) is a c i ical sys em
ha con ols popula ion densi y-associa ed gene exp ession (quo um-sensing). A low cell densi ies, low-ag ac i i y is
associa ed wi h bio ilm o ma ion ac i i y. When he quo um popula ion densi y is eached, he ag sys em is ac i a ed,
dec easing cell-su ace coloniza ion ac o s. The S aphylococcus accesso y egula o A (Sa A) sys em is a global
egula o ha p omo es bio ilm o ma ion, such as he icaRA and bap ope ons, adhesion, and oxin p oduc ion. Sa A
modula ion o gene exp ession depends on en i onmen al condi ions. Sa A enhances bac e ial coloniza ion, pa icula ly
in de ice- ela ed and ch onic in ec ions. Con e sely, in sa A mu an s, he inc eased p o ease p oduc ion can dis up
bio ilms. Sa A also ac i a es he ag quo um sensing sys em o coo dina e gene exp ession. Sa A's ole in bio ilm
o ma ion is epis a ic o ag . When ag is highly exp essed, Sa A's ep ession o p o eases is he o e iding ac o ha
p omo es bio ilm o ma ion. Fo example, in MRSA s ains, such as USA300, which ha e high ag exp ession, sa A is
equi ed o obus bio ilm de elopmen .
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2. Ma e ials and Me hods
Glucose was dissol ed and dilu ed in Lu ia B o h (LB) o use. Insulin (Humulin) was dilu ed in LB o use. O e nigh
cul u es we e inocula ed in o homologous LB o a inal concen a ion o 105CFU/ml, hen added o a ious
concen a ions o glucose and/o insulin in honey-comb pla es (200µL/well). The pla es we e incuba ed o 24 h s (37
°C , shaking). Con ols consis ed o o ganisms g own in LB alone. A e incuba ion, he pla es we e washed, d ied, and
s ained wi h c ys al iole (300µl). Bound s ain was dissol ed in absolu e alcohol (300µl) wi h abso bance de e mined
(580nm). Con ols consis ed o o ganisms g own in LB alone. Expe imen s we e done in quin uple s and epea ed once.
Da a we e e alua ed by analysis o a iance (ANOVA; G aphPad InS a 3.06 o Windows, G aphPad So wa e Inc.). Mean
alues we e conside ed signi ican ly di e en a p < 0.05 (*).
Figu e 1 E ec o insulin and glucose on bio ilm o ma ion by S. au eus. A. Pa en s ain 8325-4 bio ilm o ma ion in
esponse o insulin and glucose. B. S. au eus ag -sa A- bio ilm o ma ion in esponse o insulin and glucose. C. S. au eus
ag - bio ilm o ma ion in esponse o insulin and glucose. D. S. au eus sa A- bio ilm o ma ion in esponse o insulin
and glucose. * SEM p < 0.05 as compa ed o homologous con ol
3. Resul s and Discussion
Bio ilm o ma ion in S. au eus is egula ed, in pa , by sa A and ag ia he ex acellula signal o Ag , a pos -
ansla ionally modi ied pep ide con aining a hiolac one [7] (Figu e 1 A-D). P e ious s udies ha e shown ha insulin
is an in e -kingdom quo um signaling molecule ha , oge he wi h glucose, modula es bio ilm o ma ion [8-11]. This
esponse o S. au eus is glucose and insulin-concen a ion speci ic [12]. Whe he he insulin e ec is also unde he
egula ion o sa A in epis a ic coo dina ion wi h ag has no been de e mined. Fo he pa en s ain, 8325-4, he
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p esence o insulin alone did no signi ican ly a ec bio ilm o ma ion, as has been epo ed p e iously o quali y
con ol and clinical S. au eus isola es (Figu e 1A) [12]. Howe e , he addi ion o glucose 0.2% signi ican ly inc eased
bio ilm p oduc ion as compa ed o medium & S aphylococcus alone o glucose 0.1%. When glucose 0.2% and insulin
20µU/mL a e gi en oge he , a syne gis ic posi i e e ec on bio ilm o ma ion is measu ed. In con as , insulin did no
a ec he double nega i e S. au eus ag -sa A- s ain. Wi hou ag and sa A (Figu e 1B), S. au eus s ill esponded o
glucose in a concen a ion-speci ic manne wi h ega d o i s bio ilm o ma ion. Glucose a 0.2% esul ed in signi ican ly
(p < 0.05) inc eased bio ilm p oduc ion. In con as , he p esence o sa A and absence o ag - (Figu e 1C) es o ed he
esponse o glucose 0.2% and insulin (20µU/mL o 200µU/mL) o ha simila o he pa en s ain, bu no o he
addi ion o glucose 0.2% alone. In e es ingly, he p esence o ag oge he wi h he dele ion o sa A (Figu e 1D) esul ed
in a pa e n o bio ilm o ma ion ha , while signi ican ly less (4-6- old) han ha measu ed o he double nega i e
s ain ag -sa A-, he pa e n o bio ilm o ma ion in esponse o glucose was simila . Glucose 0.2% signi ican ly
inc eased bio ilm p oduc ion as compa ed o medium & s aphylococcus a 0.1% glucose. Insulin, ega dless o
concen a ion, had no e ec .
4. Conclusion
The indings om his s udy indica e ha sa A, in a glucose concen a ion-speci ic manne , plays a ole in he egula ion
o S. au eus esponse o insulin modula ion o bio ilm o ma ion. Fu he mo e, al hough ag is epo ed o be impo an
in S. au eus esponse o endogenous quo um signaling compounds, i appea s o be independen o insulin-media ed
bio ilm o ma ion signaling esponse in S. au eus o glucose. In addi ion, bio ilm o ma ion appea s o be egula ed, in
pa , by sa A and ag . Taken oge he , hese indings indica e ha insulin is an in e -kingdom quo um signaling
compound in S. au eus ha plays a ole in modula ing bio ilm o ma ion, pa ially unde he con ol o sa A.
Compliance wi h e hical s anda ds
Acknowledgmen s
We acknowledge he in amu al unding suppo o Midwes e n Uni e si y, O ice o Resea ch and Sponso ed P og ams.
Disclosu e o con lic o in e es
The au ho s decla e no con lic s o in e es .
Funding
This esea ch ecei ed no ex e nal unding.
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