564 JOURNAL OF COSMETIC SCIENCE
(24) Cogen AL, Nizet V, Gallo RL. Staphylococcus epidermidis functions as a component of the skin innate
immune system by inhibiting the pathogen group A Streptococcus. J Investig Dermatol. 2007 2007.
doi:10.1038/sj.jid.5700875
(25) Trilla A, Miro JM. Identifying high risk patients for Staphylococcus aureus infections: skin and soft
tissue infections. J Chemother. 1995 7(suppl 3):37–43. doi:10.1179/joc.1995.7.1.37
(26) Zheng YJ, Hunt RL, Villaruz AE, et al. Commensal Staphylococcus epidermidis contributes to skin barrier
homeostasis by generating protective ceramides. Cell Host Microbe. 2022 30(3):301–313.e9. doi:10.1016/j.
chom.2022.01.004
(27) Masuda-Kuroki K, Alimohammadi S, Di Nardo A. S epidermidis rescues allergic contact dermatitis in
sphingosine 1-phosphate receptor 2-deficient skin. Int J Mol Sci. 2023 24(17). doi:10.3390/ijms241713190
(28) McCaig LF, McDonald LC, Mandal S, Jernigan DB. Staphylococcus aureus–associated skin and soft tissue
infections in ambulatory care. Emerg Infect Dis. 2006 12(11):1715–1723. doi:10.3201/eid1211.060190
(29) Al-Ghazzewi FH, Tester RF. Impact of prebiotics and probiotics on skin health. Benef Microbes.
2014 5(2):99–107. doi:10.3920/BM2013.0040
(30) Parlet CP, Brown MM, Horswill AR. Commensal staphylococci influence Staphylococcus aureus skin
colonization and disease. Trends Microbiol. 2019 27(6):497–507. doi:10.1016/j.tim.2019.01.008
(31) Gonzalez T, Myers JMB, Herr AB, Hershey GKK. Staphylococcal biofilms in atopic dermatitis. Curr
Allergy Asthma Rep. 2017 17(12):1–11. doi:10.1007/s11882-017-0746-3
(32) Yang L, He QS, Corscadden K, Udenigwe CC. The prospects of Jerusalem artichoke in functional food
ingredients and bioenergy production. Biotechnol Rep (Amst). 2015 5:77–88. doi:10.1016/j.btre.2014.12.004
(33) Gibson GR, Hutkins R, Sanders ME, et al. Expert consensus document: the International Scientific
Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of
prebiotics. Nat Rev Gastroenterol Hepatol. 2017 14(8):491–502. doi:10.1038/nrgastro.2017.75
(34) Van De Wiele T, Boon N, Possemiers S, Jacobs H, Verstraete W. Inulin-type fructans of longer degree of
polymerization exert more pronounced in vitro prebiotic effects. J Appl Microbiol. 2007 102(2):452–460.
doi:10.1111/j.1365-2672.2006.03084.x
(35) Vogt L, Meyer D, Pullens G, et al. Immunological properties of inulin-type fructans. Crit Rev Food Sci
Nutr. 2015 55(3):414–436. doi:10.1080/10408398.2012.660266
(36) Takeuchi K, Asakawa M, Hashiba T, Takeshita T, Saeki Y, Yamashita Y. Effects of xylitol-containing
chewing gum on the oral microbiota. J Oral Sci. 2018 60(4):588–594. doi:10.2334/josnusd.17-0446
(37) Delmondes GA, Bezerra DS, Dias DQ, et al. Toxicological and pharmacologic effects of farnesol
(C15H26O): A descriptive systematic review. Food Chem Toxicol. 2019 129:169–200. doi:10.1016/j.
fct.2019.04.025
(38) Katsuyama M, Kobayashi Y, Ichikawa H, et al. A novel method to control the balance of skin microflora:
Part 2. A study to assess the effect of a cream containing farnesol and xylitol on atopic dry skin. J
Dermatol Sci. 2005 38(3):207–213. doi:10.1016/j.jdermsci.2005.01.003
(39) Katsuyama M, Ichikawa H, Ogawa S, Ikezawa Z. A novel method to control the balance of skin
microflora: Part 1. Attack on biofilm of Staphylococcus aureus without antibiotics. J Dermatol Sci.
2005 38(3):197–205. doi:10.1016/j.jdermsci.2005.01.006
(40) Braff MH, Zaiou M, Fierer J, Nizet V, Gallo RL. Keratinocyte production of cathelicidin provides
direct activity against bacterial skin pathogens. Infect Immun. 2005 73(10):6771–6781. doi:10.1128/
IAI.73.10.6771-6781.2005
(41) Two AM, Nakatsuji T, Kotol PF, et al. The cutaneous microbiome and aspects of skin antimicrobial
defense system resist acute treatment with topical Skin Cleansers. J Invest Dermatol. 2016 136(10):1950–
1954. doi:10.1016/j.jid.2016.06.612
(42) Christensen GJM, Brüggemann H. Bacterial skin commensals and their role as host guardians. Benef
Microbes. 2013 5(2):201–215. doi:10.3920/BM2013.0013
(43) Oyinloye BE, Adenowo AF, Kappo AP. Reactive oxygen species, apoptosis, antimicrobial peptides and
human inflammatory diseases. Pharmaceuticals (Basel). 2015 8(2):151–175. doi:10.3390/ph8020151

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J. Cosmet. Sci., 75.6, 565–580 (November/December 2024)
*Address all correspondence to Alicia Roso, alicia.roso@airliquide.com
An Innovative Model Based on Wild Type Bacteria
Co-Culture to Identify Cosmetic Ingredients That Respect
the Skin Microbiota
ALICIA ROSO, SOPHIE PÉCASTAINGS, SOPHIE CAMBOS, RICHARD MARTIN,
LAURA BAUCHET, BENOÎT ROUBINET, LUDOVIC LANDEMARRE AND
CHRISTINE GARCIA
Seppic Research and Innovation, La Garenne Colombes, Franc (A.R., S.P., S.C., C.G.)
Mercurialis, Rochecorbon, France (R.M.)
GLYcoDiag, Orléans, France (L.B., B.R., L.L.)
Accepted for publication October 02, 2024.
Synopsis
Human skin is the home of thousands of microorganisms that are well adapted to that hostile environment.
Divesting from the hygienist theory, microorganisms are not considered as potential pathogens anymore, but
as symbionts that must be preserved. With this consideration in mind, cosmetic formulators have sought
ingredients able to preserve and not interfere with cutaneous bacteria. The aim of the present study is to
design a relevant and representative in vitro model of bacteria coculture able to identify ingredients that do not
harm skin microbiota. A protocol was designed to obtain a coculture of the five main bacterial representatives
of the face’s microbiota: Cutibacterium acnes Staphylococcus epidermidis Streptococcus mitis Micrococcus luteus, and
Corynebacterium xerosis, from wild isolates, and in proportions representative of the cheek microbiota. After
8 hours of contact with the test ingredients, bacteria concentrations were measured. A score establishing
the impact of ingredients was implemented, based on the logarithmic reduction of the five species. This
methodology correctly discriminated between known substances with neutral or bactericidal effects. Finally,
four substances used in cosmetic products were evaluated. The proposed model is adapted to screen for
new “microbiota-friendly” ingredients as a first step to design formulations intended to preserve the skin
microbiota.
INTRODUCTION
The human skin represents an interface of 1.5 –2 m2 between the body and its environment.
This complex surface is naturally colonized by a variety of microorganisms that, together,
constitute the skin microbiota. Bacteria are the main representatives (104–106 Colony
Forming Units, or CFU, per cm2), but depending on the area, yeasts and viruses can also
represent a significant proportion of the skin microbiota.1,2 Microorganisms colonizing the
skin, defined as commensals as opposed to transient microorganisms, are very well adapted