Bacterium Hafnia alvei secretes l-methioninase enzyme: Optimization of the enzyme secretion conditions

I isolated bacteria from blue cheese in order to find bacterial strains secreting l-methioninase enzyme, and optimized the conditions for the most efficient enzyme secretion. The efficient isolate, identified according to the 16S rRNA gene sequence analysis, was Hafnia alvei belonging to Enterobacteriaceae. I confirmed that the H. alvei strain harbored the methionase gene, mdeA (1194 bp). The environmental (pH, temperature) and nutritional (carbon and nitrogen sources and Mg concentration) factors influencing the l-methioninase production of H. alvei were optimized. The highest yield of l-methioninase enzyme was reached after 48 h of incubation when the acidity of the growing medium was adjusted to pH 7.5 and the temperature was 35 °C. The following concentrations of the supplements increased the l-methioninase yield in the medium: galactose (2.0 g L(−1)), MgSO(4) (0.25 g L(−1)), l-methionine as an inducer (2.0 g L(−1)), and l-asparagine as an additional N source (1.5 g L(−1)). I introduce a bacterial strain of H. alvei that is previously unreported to secrete l-methioninase enzyme and show that a carbon source is a mandatory supplement whereas l-methionine is not a mandatory supplement for l-methioninase enzyme production of H. alvei.