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L‐methioninase production by Aspergillus flavipes under solid‐state fermentation
Author(s) -
ElSayed Ashraf S. A.
Publication year - 2009
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.200800318
Subject(s) - bran , solid state fermentation , fermentation , food science , casein , substrate (aquarium) , enzyme assay , chemistry , biology , enzyme , biochemistry , raw material , ecology , organic chemistry
Solid‐state fermentation was carried out for the production of extra‐cellular L‐methioninase by Aspergillus flavipes (Bain and Sart.) using nine agro‐industrial residues, namely wheat bran, rice bran, wheat flour, coconut seeds, cotton seeds, ground nut cake, lentil hulls, soya beans and chicken feathers. Chicken feathers were selected as solid substrate for L‐methioninase production by A. flavipes . The maximum L‐methioninase productivity (71.0 U/mg protein) and growth (11 mg protein/ml) of A. flavipes was obtained using alkali pretreated chicken feathers of 50% initial moisture content as substrate supplemented with D‐glucose (1.0% w/v) and L‐methionine (0.2% w/v). External supplementation of the fermentation medium with various vitamin sources has no overinductive effect on L‐methioninase biosynthesis. The partially purified A. flavipes L‐methioninase preparation showed highest activity (181 U/ml) at pH 8.0 with stability over a pH range (pH 6–8) for 2 h. L‐methioninase activity was increased by preincubation of the enzyme for 2 h with Co 2+ , Mn 2+ , Cu 2+ and Mg 2+ and strongly inhibited by the presence of EDTA, NaN 3 , Li 2+ , Cd 2+ , DMSO and 2‐mercaptoethanol. The enzyme preparation has a broad substrate spectrum showing a higher affinity to deaminate L‐glycine, N ‐acetylglucosamine and glutamic acid, in addition to their proteolytic activity against bovine serum albumin, casein, gelatin and keratin. The partially purified enzyme was found to be glyco‐metalloproteinic in nature as concluded from the analytical and spectroscopic profiles of the enzyme preparation. The demethiolating activity of the enzyme was also visualized chromogenially. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)