Isolation and characterization of a novel l-Methionine producer from Mahanadi river site in Sambalpur district of Odisha, India

Abstract

l-methionine is an essential amino acid for human nutrition. Its global market demand is expanding gradually. Even though large scale production of stereo-specific amino acids by fermentation was initiated with the isolation of l-glutamic acid overproducer strain in 1957, but due to several drawbacks, l-methionine fermentation in large scale was not successfully initiated. In the present study, isolation, molecular characterization as well as strain improvement have been done for l-methionine overproduction by a newly isolated bacterial strain from Sambalpur district, near Hirakud dam, Odisha. Based on the morphological and molecular characterization, the pale colored colony forming rod shaped, Gram negative, non-motile bacterium was identified as Alcaligenes faecalis strain. Mutational induction was done to develop l-methionine overproducers by N-methyl-N’-nitro-N-nitrosoguanidine (NTG) and UV rays. Finally, l-ethionine-resistant strain was developed to overcome feed-back inhibition. The mutant strain Alcaligenes faecalis ATCXT3624 appeared to be l-homoserine auxotroph in further studies. The strain could produce 20.1 ± 0.32 mg l-methionine/mL in subsequent submerged fermentation before optimization of culture conditions. The relevance of the study was discussed in relation to commercial production of l-methionine.