Biosynthesis of tannase and hydrolysis of tannins to gallic acid by aspergillus awamori — optimisation of process parameters

Abstract

Tannin acyl hydrolase (tannase) is an industrially important enzyme produced by a large number of fungi. Tannic acid concentration, agitation speed and pH during the fermentation were identified as important process parameters effecting cell growth and enzyme synthesis by Aspergillus awamori. These parameters were optimised in a laboratory bioreactor by response surface methodology using Box and Behnken factorial design to determine the optimum conditions for enzyme production and gallic acid accumulation. Under optimum process conditions for enzyme synthesis, the fermentation run lasted 60 h with an initial tannic acid concentration of 35.0 g l, yielding biomass concentration of 7.13 g l containing 771 IU of intracellular tannase per gram dry cell weight and 19 g l of gallic acid. However, maximum gallic acid accumulation (40.3 g l) was obtained in 24 h with an initial substrate concentration of 45 g l.