Influence of physical, chemical and inducer treatments on menaquinone-7 biosynthesis by Bacillus subtilis MTCC 2756

Abstract

Effects of physical and chemical treatment on nutrient mobility, their utilization for menaquinone-7 (MK-7) biosynthesis; growth of microbial cells has been investigated in the present research. Bacillus subtilis MTCC 2756 fermented medium was supplied with 1-naphthol and hypoxanthine resulted in a significant increase in MK-7 production. Ultrasonication, electric shock, heat shock, and tween 80 were used for inducer uptake by Bacillus subtilis and menaquinone-7 production. Induction of Bacillus subtilis (at 16 hours of fermentation) using 1-naphthol (2 mg/ml), along with tween 80 (0.1%) was found to increase the MK-7 production by 3 fold i.e. 14.4 µg/ml as compared to the untreated fermentation medium. The ultrasonicated (ultrasonic power 33 W, treatment time 4 min and frequency 36 KHz) microbial cells yielded higher biomass and 2.5 fold increase in the MK-7 production i.e.10.3 µg/ml than control. 1-naphthol along with physical or chemical treatment is required for maximum MK-7 production by Bacillus subtilis.

Keywords

• menaquinone-7
• 1-naphthol
• hypoxanthine
• ultrasonication
• tween 80