ABSTRACT
Extracellular tannase and gallic acid were produced optimally under submerged fermentation at 37 0C, 72 h, pH 5.0, 10 percent(v/v) inoculum and 4 percent(w/v) of the agroresidue pomegranate rind (PR) powder by an Aspergillus niger isolate. Tannic acid (1 percent) stimulated the enzyme production by 245.9 percent while with 0.5 percent glucose, increase was marginal. Tannase production was inhibited by gallic acid and nitrogen sources such as NH4NO3, NH4Cl, KNO3, asparatic acid, urea and EDTA. The partially purified enzyme showed temperature and pH optima of 35 0C and 6.2 respectively which shifted to 40 0C and 5.8 on immobilization in alginate beads. Activity of the enzyme was inhibited by Zn+2, Ca+, Mn+2, Mg+2, Ba+2and Ag+. The immobilized enzyme removed 68.8 percent tannin from juice of aonla/myrobalan (Phyllanthus emblica), a tropical fruit, rich in vitamin C and other essential nutrients. The enzymatic treatment of the juice with minimum reduction in vitamin C is encouraging as non enzymatic treatments of myrobalan juice results in vitamin C removal.
Subject(s)
Gallic Acid/analysis , Gallic Acid/isolation & purification , Aspergillus niger/enzymology , Aspergillus niger/isolation & purification , Enzymes, Immobilized/analysis , Enzymes, Immobilized/isolation & purification , Fermentation , Lythraceae/enzymology , Tanacetum parthenium/growth & development , Tanacetum parthenium/enzymology , Enzyme Activation , Fruit , MethodsABSTRACT
Effects of xylose on xylanase production by a thermophilic Bacillus sp showed diverse patterns on corn cob (CC) and wheat bran (WB) as sole carbon sources in solid- state fermentation (SSF) and submerged fermentation (SmF). Supplementation of these media with either mineral salt solution (MSS) or yeast extract peptone (YEP) also exerted variable effects. While under SSF, xylose stimulated xylanase synthesis by 44.01 percent, on wheat bran supplemented with MSS, it decreased the enzyme activity by 12.89 percent with YEP supplementation. In SmF, however the enzyme synthesis was stimulated by xylose on supplementation with both MSS and YEP by 41.38 percent and 27.47 percent, respectively. On corn cob under SSF, xylose repression was significant both with MSS (26.92 percent) and YEP (23.90 percent) supplementation. Repression by xylose also took place on corn cob and YEP (19.69 percent) under SmF, while significant stimulation (28.55 percent) was observed by MSS supplementation. The possible role of media composition and fermentation conditions in the regulation of xylanase synthesis by xylose is discussed.