Effect of Penicillin on Amino Acid Fermentation

The effect of penicillin G(k) was first investigated on l-homoserine production by Micrococcus glutamicus 534-Co 147 (a threonine requiring mutant). The addition of 4 u/ml of penicillin, 7 to 9 hours after inoculation, brought about the conversion of l-homoserine to l-glutamic acid production. Similar phenomena were observed in l-lysine and l-valine fermentations. In these cases, a homoserine requiring and a leucine requiring mutant of M. glutamicus were used respectively. A marked conversion from lysine and valine to glutamate accumulation occured by penicillin addition. However, in l-isoleucine fermentation with Brevibacterium ammoniagenes ATCC 6871, no glutamate accumulation took place and isoleucine yields were remarkably decreased.