Concomitant yield optimization of tannase and gallic acid by Bacillus licheniformis KBR6 through submerged fermentation: An industrial approach

Abstract

The present study is concerned with the evaluation of tannase and gallic acid production efficacy of Bacillus licheniformis KBR6 under different environmental conditions through submerged fermentation. Results have shown that different environmental conditions and mineral sources have differential influences on tannase and gallic acid production. Highest tannase and gallic acid yield was observed at incubation period of 18 h and 22 h, respectively. At tannic acid concentration of 15 g/l, maximum cell mass (0.75 g/l), cell yield coefficient (0.08 g/g), specific growth rate (37.5 mg/g/h), tannase yield (16.3 U/g) and specific tannase production rate (0.80 U/g/h) were observed, however, at higher tannic acid concentration a decrease in tannase yield and production rate were observed, but gallic acid production increased with increasing tannic acid concentration. Additional carbohydrate sources like glucose, fructose, and lactose showed positive influence on enzyme yield. Among the studied nitrogen sources urea and NH4Cl, and of the phosphate sources KH2PO4 showed favourable effects on cell growth and simultaneous enzyme and gallic acid production. Temperature of 35 °C was found to be optimum for tannase and gallic acid production. Of all the studied metal ions Ca2+, Mg2+ and Na+ showed positive effect whereas, Co2+, Ag2+, Pb2+, Hg2+ showed inhibitory effects.