ASSIMILATION OF INGREDIENTS BY MICROORGANISMS 861 3000 1700 1400 1000 Absorption Lcm -•) Figure •. Infrared spectrum of liquid paraffin (paraffin-rich) after incubation 6 lO Figure 5. Chrotnatogrmn of liquid paraffin (paraffin-rich)

862 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table IX Assimilation by Pseudomonas No. 25 of Various Esters Ester Structure Growtha Myristyl myristate Isopropyl myristate 2-Hexyldecyl myristate Diisopropyl adipate Di(2-ethylhexyl) adipate Di(2-hexyldecyl) adipate Glycerol tricaprylate Glycerol trimyristate Glycerol tri-2-ethyl- hexanoate b • Sy•nbols: q-q-, abundant growth q-, moderate growth growth. b Synthesized in laboratories of Shiseido Co. +, slight growth --, no group increased. In the case of diesters, the utilization became more difiScult as the branched chain length was increased. The gas chromato- grams shown in Figs. 6 and 7 illustrate the degradation of the glycerides. As for glycerol tri-2-ethylhexanoate, there was little difference between before and after incubation. In the case of glycerol tricaprylate, three new peaks appeared after incubation and the peak for triglyceride de- creased. These three peaks are perhaps free fatty acid, monoglyceride, and diglyceride (right to left). A time course of the biodegradation of glycerol tricaprylate is repre- sented in Fig. 8. The content of triglyceride and the pH value of the