Revista Colombiana de Ciencias Pecuarias (Aug 2014)
Production of extracellular α-galactosidase by Bacillus sp. LX-1 in solid state fermentation for application as a potential feed additive
Abstract
Background: α-galacto-oligosaccharides, including raffinose and stachyose, are present in soybean meal and used widely as a protein source in poultry diets. These compounds have anti-nutritive effects that ultimately reduce performance and value of birds. Thus, the addition of exogenous α-galactosidase to poultry diets -which can initiate the digestion of these non-digestible sugars- can be an effective strategy to solve the nutritional disorders associated with consumption of these oligosacharides. Solid state fermentation (SSF) has drawn attention for the production of microbial enzymes, due to the possibility of using cheap and abundant agro-industrial residues as substrates. Objective: to present information on α-galactosidase production under SSF conditions by an Antarctic bacterial isolate, Bacillus LX-1. Methods: initially, wheat bran, soybean meal, corn flour and the combinations of these individual substrates with nutritive supplements containing 1% galactose, 0.5% yeast extract, 1% tryptone, and 0.001% MnSO(4)4H2O were evaluated to select an optimal medium in SSF to produce extracellular α-galactosidase. Certain fermentation parameters involving incubation time, moisture content, and initial pH were investigated separately. Additional studies were conducted to evaluate the influence on enzyme production of different carbon sources (glucose, sucrose, galactose, lactose, and maltose) and nitrogen sources (peptone, tryptone, sodium nitrate and ammonium sulfate). Results: a medium containing soybean meal resulted in best α-galactosidase synthesis and was used for further SSF explorations with Bacillus sp. LX-1. Maximum enzyme production was observed at a growth period of 72 h, 75% moisture content and pH 8.0. Enzyme activity was enhanced in the presence of galactose or lactose as the carbon source, and tryptone or peptone as the nitrogen source. Conclusion: this SSF technique could be potentially used to produce α-galactosidase for poultry feed.
