Enhancement of methionine production by methionine analogue ethionine resistant mutants of <i>Brevibacterium heali</i>

Abstract

Abstract In order to improve the methionine yield of the isolate B. heali , attempts were made to isolate mutants resistant to the methionine analogue DL ‐ethionine after mutagenesis with N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (NTG). The minimum inhibitory concentration (MIC) of ethionine for B. heali was found to be 2 mM. After mutagenesis and screening, five mutants resistant to 50 mM of ethionine were isolated. The yield of the best ethionine resistant mutant, B. heali Br EthR , was 13 mg/l of methionine medium under optimum cultivation conditions.