Production of L-lysine by Corynebacterium glutamicum using aqueous leaf extracts of tropical grasses as substrate

Abstract

L-Lysine is a highly valuable amino acid widely used in various industries, particularly in food and animal feed. Extensive research has been conducted to enhance its production, and this study aimed to evaluate the capability of Corynebacterium glutamicum ATCC 13032 for producing L-lysine from aqueous leaf extracts of tropical grasses. The submerged fermentation technique was employed for this purpose, 10 g sample used; 2 mL culture inoculated 100 mL flask with 20 mL broth. Incubated 96 h at 30 °C, 160 rpm for growth and lysine production. Significant increases (p < 0.05) in L-lysine concentration were observed in the fermented aqueous leaf extracts of various tropical grasses when inoculated with C. glutamicum, compared to the non-inoculated samples. Among the different grasses tested, the fresh aqueous leaf extract of Indian almond demonstrated the highest L-lysine concentration (2.4 ± 0.05 mg/g). Furthermore, both fresh and dried aqueous leaf extracts exhibited a significant increase (p < 0.05) in soluble protein concentration when subjected to fermentation. Notably, the fermented extracts of tropical grasses inoculated with C. glutamicum displayed an overall increase in the content of total phenolics and flavonoids, indicating a potential enhancement of their bioactive compounds. Additionally, the activities of amylase and protease enzymes substantially rose in the fermented extracts. This study highlights a promising biotechnological approach for the production of L-lysine using aqueous leaf extracts of tropical grasses, offering potential benefits for health-related and industrial applications.