%0 Journal Article
%T Production of ¦Â-Glucosidase from a Newly Isolated Aspergillus Species Using Response Surface Methodology
%A Pilanee Vaithanomsat
%A Molnapat Songpim
%A Taweesiri Malapant
%A Akihiko Kosugi
%A Warunee Thanapase
%A Yutaka Mori
%J International Journal of Microbiology
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/949252
%X A newly isolated fungus Aspergillus niger SOI017 was shown to be a good producer of ¦Â-glucosidase from all isolated fungal strains. Fermentation condition (pH, cellobiose concentration, yeast extract concentration, and ammonium sulfate concentration) was optimized for producing the enzyme in shake flask cultures. Response surface methodology was used to investigate the effects of 4 fermentation parameters (yeast extract concentration, cellobiose concentration, ammonium sulfate concentration, and pH) on ¦Â-glucosidase enzyme production. Production of ¦Â-glucosidase was most sensitive to the culture medium, especially the nitrogen source yeast extract. The optimized medium for producing maximum ¦Â-glucosidase specific activity consisted of 0.275% yeast extract, 1.125% cellobiose, and 2.6% ammonium sulfate at a pH value of 3. 1. Introduction Lignocellulose is the major component of biomass, representing the most abundant renewable organic source in soil. It consists of three polymers types, cellulose, hemicelluloses, and lignin that are strongly intermeshed and chemically bonded by noncovalent forces and by covalent cross-linkages [1]. The enzymatic hydrolysis of cellulosic material into glucose involves the synergistic action of at least three different enzymes: endoglucanase or endo-¦Â-1,4-glucanase, exoglucanase or exocellobiohydrolase, and ¦Â-1,4-glucosidase or cellobiase [2]. Endo-¦Â-1,4-glucanase catalyzes the hydrolysis of cellulose by randomly splitting the sugar residues within the molecule, whereas exo-¦Â-1,4-glucanase removes monomers and dimmers, from the end of the glucan chain. The ¦Â-1,4-glucosidase hydrolyzes glucose dimers and in some cases, cellulose oligosaccharides to glucose. Since cellobiose inhibits the action of endo- and exoglucanases, ¦Â-glucosidase contributes to the efficiency of this process. Very strong activity of ¦Â-glucosidase is thus needed for the pretreatment step of lignocellulose before a further ethanol conversion. In addition to the role in cellulose degradation, ¦Â-glucosidase has also been attributed to several other applications. This includes the applications in pharmaceutical, cosmetic, and detergent industries [3]. Most of the commercially available ¦Â-glucosidase are served as parts of cellulase enzymes. There are only two of those served as the actual ¦Â-glucosidase; one is the Novozym188 from Aspergillus niger (Novo Industri A/S, Denmark) and another one is ¦Â-glucosidase also from A. niger (Fluka, Switzerland). More screenings have been attempted for the novel sources of much higher ¦Â-glucosidase activity. Vaithanomsat
%U http://www.hindawi.com/journals/ijmicro/2011/949252/