Microbial production of tannase using agro waste
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
Tannase (tannin acyl hydrolase, E.C.3.1.1.20) is an inducible enzyme that has wide
applications in different food and feed industries including production of beverages, cosmetic
chemicals and in clarification of beer and fruit juice. It has also been used for bioremediation
of tannins from effluents of leather industries. Attempt was made for isolation of tannase
producing microbes (bacteria/fungi) from tannery effluents using tannic acid supplemented
media. On the basis of qualitative (zone of hydrolysis) assay, four fungal isolates – AV1,
AV2, AV3 and AV4 were found to be more efficient than bacterial isolates for tannase
production and the maximum zone was shown by AV3 isolate i.e. 2.3 cm. For the
morphological characterization of fungal isolates, lactophenol cotton blue staining and
Scanning Electron Microscopy were done. Isolate AV1, AV2, AV3 and AV4 were found to
show morphological similarities to genera Penicillium, Fusarium, Aspergillus and
Trichoderma, respectively. Quantitative tannase production by the selected four isolates
(AV1, AV2, AV3 and AV4) for seven consecutive days revealed AV3 to be the maximum
tannase producer (25.33 U/ml) on 5th day of incubation. Four different agrowastes i.e. spent
tea powder, coconut coir, corn husk and fruit baggase were used as substrates for tannase
production using selected isolate AV3 and the maximum tannase production (35.62 U/ml)
was obtained using spent tea powder as substrate at pH 5.5 and temperature 40oC.
Optimization of process parameters for maximum tannase activity with central composite
design using response surface methodology reveals maximum tannin hydrolysis
(93.33µMmin-1) at a temperature of 600C, pH 8.0 and 5% substrate concentration. On partial
purification, by ammonium sulphate precipitation followed by dialysis using membrane-70,
activity of the tannase increased to 153.33µMmin-1 and the yield of the enzyme was 83.33%.
Partially purified enzyme was used for detannification of pomegranate juice and was found to
reduce tannin content from 2.76 mg/ml to 1.03 mg/ml but with slight decolorization of juice.
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