APTITUDE OF CHEESE BACTERIA FOR VOLATILE S-METHYL THIOESTER SYNTHESIS.1. EFFECT OF SUBSTRATES AND PH ON THEIR FORMATION BY BREVIBACTERIUM LINENS GC171

The aptitude of resting cells of Brevibacterium linens G171 to synthes ize S-methyl thioesters was studied in presence of methanethiol and ni ne short-chain fatty acids individually or as a mixture. Esterificatio n of acetic, propionic and methyl branched-chain acids occurred with m ethanethiol alone and was enhanced by fatty acid addition. Addition of n-chain, 3-hydroxybutyric and 2-hydroxyvaleric acids allowed synthesi s of n-chain thioesters up to thiocaproate. The kinetics of production and the effect of concentrations of both substrates and of cells were tested. The optimum pH for synthesis varied according to the kind of thioesters produced. Results suggested that thioesters were derived ma inly from acyl-CoA from different metabolic breakdowns, such as the de gradation of fatty acids or some amino acids, and that several acyltra nsferases could be involved.