Isolation to purification: An integrated study on lysine production by Bacillus megaterium NTJT4 from medicinal plant rhizosphere

L-lysine stands out as a commercially important amino acid vital for maintaining balanced nutrition, immune function and healthy development in humans and animals. As global demand for lysine continues to rise each year, large-scale production is required to keep pace with this growing need. In the present study, L-lysine production was accomplished through a fermentation process utilizing isolated bacterial strains from soil. After conducting primary screening, Bacillus megaterium NTJT4 was identified as the highest lysine producer. Various fermentation parameters including fermentation time, pH, temperature, different carbon and nitrogen sources, glucose levels, ammonium sulfate concentration, growth stimulators, and vitamin concentrations were evaluated to optimize lysine production. The study found that the optimal conditions for lysine production were 72 hours, pH 7.0, and 37 °C. The effect of different carbon and nitrogen sources showed that 8% glucose and 1% ammonium sulfate resulted in increased lysine production (4.86 ± 0.20 mg/mL and 3.95 ± 0.14 mg/mL respectively). Media with combination of peptone and yeast extract as growth stimulators showed increased lysine yield (4.86 ± 0.31 mg/mL) and addition of 100 µg/mL thiamine-HCL as a source of vitamin resulted in increased lysine yield (5.37 ± 0.16 mg/mL). Amberlite IR‑120-based ion‑exchange chromatography achieved 100.0% purity and 58.0% recovery of lysine. The purified lysine concentration reached 13.44 mg/mL with a purification fold of 3.85. These results indicate that the newly isolated Bacillus megaterium NTJT4 possesses considerable potential for diverse biotechnological and industrial applications, particularly in microbial amino acid production.