BIOLOGICAL-ACTIVITY OF METHIONINE DERIVAT IVES .1. MICROBIOLOGICAL ACTIVITY OF METHIONINE DERIVATIVES

Methionine (MET) as an essential aminoacid, plays an important role in the protein synthesis and transmethylation processes, Owing to its li potropic effect, it can advantageously be used - among others - in the prevention of production diseases of high yielding cows. However, MET and its different derivatives given together with the feed can be dec omposed in the rumen due to the microbial fermentation. Microbiologica l utility of different MET derivatives [L-, D-, DL-methionine, DL-meth ionine-sulfoxid, DL-methionine-sulfone, L-cysteine, DL-methionine-hydr oxy-analogue (HMB), DL-S-methyl-methionine-sulfonium-chloride (S-methy l-MET, SMM), DL-2-hydroxy-4-dimethylthiobutyric acid (S-methyl-HMB)] w as studied using Lactobacillus strains (Lactobacillus plantarum ATCC 8 014, Leuconostoc mesenteroides ATCC 8042 and Lactobacillus casei ATCC 7469). L. plantarum and L. mesenteroides utilized equally well the MET , however S-methyl-MET proved to be active only for L. plantarum. HMB was utilized by none of the studied bacterial strains. Effect of MET L and D stereoisomers on the growth of L. plantarum did not differ sign ificantly (Fig. 1). Methionine-sulfoxid reached only approx. 70% of th e effect of MET while methionine-sulfone proved to be inactive. Cystin e and its derivatives could not be substitute methionine to cover the methionine requirement of L. plantarum. S-methyl-MET, as a methionine source, was utilized only to a lesser manner, however its effect could significantly be increased in the presence of homocysteine. HMB and S -methyl-HMB, as a methionine source, could not be utilized, even in th e presence of homocysteine. The results obtained showed that MET and i ts examined derivatives join to the methionine-metabolism of L. planta rum according to the pathway shown in Fig. 2.