Gallic acid is a very useful chemical mostly utilized as an intermediate in the production of trimethoxy benzaldehyde, which is used in pharmaceutical industry for the production of Trimethoprim, a broad spectrum antibiotic. It has huge demand in India though it ia an imported item. It is mainly used for manufacture of propyl galllate, inks, and photographic developer, in testing free mineral acids, dihydroxy acetone and alkaloids. The worldwide annual demand of gallic acid is about 8,000 tons. Conventionally gallic acid is produced by acid hydrolysis of tannins, but this process releases a large amount of toxic effluent that causes environmental hazards. Production of gallic acid through fermentation of cashew tannins using suitable tannase producing microorganism is preferred today.
The Present study deals with the microbiological conversion of gallotannin to 3, 4, and 5 – tri hydroxy benzoic acid by a mutant strain of Aspergillus oryzae. Spores from Aspergillus oryzae were subjected to UV, heat and NTG (3-nitro, 5-methylguanidine) mutagenesis. A few colonies were screened from the selected media for tannase study. Amongst all, the best mutant isolated from the heat treatment (60 _C for 60 min) was ATTC9 3692. The maximum yield of gallic acid and tannase in case of mutant strain was 95.2% and 53.6 U/ml with an incubation period of 30 h as compared to wild strain where the incubation period was 48 h with an enzyme activity of 44.2 U/ml and gallic acid yield of 94%, respectively. The mutant was sensitive to tetracycline and was also an over-producer of protease and amylase.