Screening of extracellular tannase-producing fungi: Development of a rapid and simple plate assay.

Fifty fungi belonging to various groups were screened for extracellular tannase.Among all the fungi tested Aspergillus niger and Aspergillus japonicus were the best producers (29.13 and 25.6 U/ml, respectively).The enzyme was produced within 48 h of growth when tannic acid was used as the sole source of carbon.The present paper describes a simple tannic acid agar which can be conveniently used for screening purposes since a high correlation coefficient exists between halo size and quantitative production of enzyme in broth.Tannase, tannin acyl hydrolase (EC 3.1.1.20),catalyzes the de-esterification of tannins to gallic acid and glucose.Many microorganisms (4,8) especially fungi are known to produce this enzyme both as membrane bound and extracellular forms.This enzyme is extremely important in the recycling of plant biomass (I1), in treating tannery effluents and also in the production of gallic acid, a chemical used in pharmaceuticals (6).To date, very few systems have been purified and characterized (1,7,9,10).The present paper deals with screening of fungi and the development of a simple plate assay for rapid screening of tannase-producing microbes.Fifty fungal cultures were obtained from the departmental stock culture collection and were screened for their tannase producing ability.Screening for tannase production was done in Czapek Dox's minimal medium containing commercial tannic acid (C76H42056) as the sole carbon source.The basal medium contained (gl-'): tannic acid 10; NaNO2, 6; KCI 0.52; MgSO4.7H2O0.52; KH2P04 1.52; Cu(N03)2.3H20traces; ZnSO4.7H2Otraces; FeS04.7H20traces.The solution of tannic acid was sterilized separately by passing through a membrane