1. Soc. Cosmet. Chem., 22, 851-865 (December 9, 1971) Assimilation of Selected Cosmetic Ingredients by Microorganisms MITSUO YANAGI, B.S., and GENGO ONISHI, B.S.* Presented May 24-25, 1971, Seminar, Washington, D.C. Synopsis--A study was made of the possible ASSIMILATION by various MICROORGAN- ISMS of INGREDIENTS com•nonly used in the formulation of COSMETIC products. Hydrocarbons, high molecular weight alcohols, esters and fatty acids, and silicones were studied. Microorganisms used in this study were isolated from cosmetic products. Some species of PENICILLIUM, CANDIDA, and PSEUDOMONAS were noted to demonstrate strong ability to assimilate some of these ingredients. Of the materials tested, mineral oil, oleyl alcohol, stearyl alcohol, propylene glycol, isopropyl myristate, 2-hexyldecyl myristate, oleic acid, and stearic acid were found to be utilized as the sole source of carbon by most of the test organisms. Solid paraffin, multiwax, camellian, squalane, silicones, hexadecyl alco- hol, polyethylene glycol, and di(2-hexyldecyl) adipate were not utilized by the organisms. The relationship between microbial assimilation and CHEMICAL STRUCTURE of sub- strate was also determined by the use of different esters. INTRODUCTION The ability to utilize hydrocarbons and their derivatives as the sole carbon source has been demonstrated by many different types of microorganisms. These organisms include fungi, yeasts, Streptomyces, Nocardia, and bacteria. Many of these organisms are found not only in the soil surrounding petroleum fields but in that of ordinary surround- ings, including soil in which vegetables and fruits are grown. It is well known that many different kinds of microorganisms are often isolated from cosmetic products. While some of these present no problems, others are responsible for changes in odor or breakdown of emulsion systems used in cosmetic formulation. * Shiseido Co., Ltd., Research Laboratory, Tokyo, Japan. 851

852 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Cosmetic products, in particular creams and lotions, are composed of an aqueous phase, an oil phase, and surfactants. Ingredients used in the formulation of the oil phase include hydrocarbons, high molecular weight alcohols, fatty acids, esters, silicones, and other substances. Some of these ingredients were selected for this study and investigated in order to determine the microbial assimilation by organisms which were isolated from cosmetic products. Another objective of this investi- gation was to determine the relationship between assimilation and the chemical structure of selected substrates. EXPERIMENTAL Several different microorganisms were used in this study. They were isolated from various cosmetic products and included 23 strains of bac- teria, 25 strains of yeasts, and 17 strains of fungi. Preparation of Culture Media Two different formulations of culture media were used. One me- dium was used for yeasts and fungi while another composition was used for bacteria. The compositions of the media are shown in Table I. Various substrates were used in this study and represented the sole carbon source. Table II lists the materials which were used as the sub- strate. Preparation of Organisms and Test Solutions The bacteria and yeasts used in this study were incubated on a slant culture at 30øC for 48 hr. These cells were then suspended in a 0.006% Table I Compositions of Media For Yeasts For Bacteria and Fungi (grams) (grams) KH2O4 0.5 2.3 K2HPO4 2.5 0.7 MgSO4 0.3 0.3 CaCI.0.3 0.3 (NH4)2SO4 3.0 3.0 NaC1 0.3 0.3 Water 1000 1000 Substrate 10.0 10.0 pH 6.8-7.0 5.5-5.6