Efficiency of rice straw lignocelluloses degradability by Aspergillus terreus ATCC 74135 in solid state fermentation

The ability of Aspergillus terreus for the production of cellulolytic enzymes and reduction of lignocellulose contents of rice straw in solid state fermentation was investigated in this study. Results suggested that, 8 days fermentation was appropriate, with enzymes activities as follows: FPase = 410.76 U/gDM, CMCase = 351.96U/gDM, -glucosidase = 16.37 U/gDM, xylanase = 6166.01 U/gDM and amyloglucosidase = 425.04 U/gDM (with maximum 993.71 U/gDM on day 6). In addition, the solid state fermentation significantly (P < 0.01) reduced the concentrations of NDF, ADF, cellulose and hemicellulose in the rice straw by 19.96, 13.8, 16.32 and 32.87%, respectively. The high degradation of the hemicellulose was reflected by the high activity of xylanase enzyme, which hydrolyses xylan in hemicellulose to xylose. Higher reducing sugar and microbial cell mass productions were also obtained after 8 days fermentation. Present data showed that, A. terreus is capable of producing high quantity of cellulolytic enzymes for the reduction of lignocellulose contents of biomass in a shorter incubation time when compared with the previously reported for biological treatment of agricultural by-products using white rot fungi.Key words: Aspergillus terreus, biomass, biological treatment, enzyme activity, solid state fermentation

Effects of Aspergillus niger (K8) on nutritive value of rice straw

The objective of this study was to evaluate the use of solid state fermentation for the improvement of the quality of rice straw as animal feed. Rice straw was fermented using Aspergillus niger (K8) with and without additional nitrogen source (urea). Cellulose, hemicelluloses, organic matter (OM), dry matter (DM), acid detergent fibre (ADF), neutral detergent fibre (NDF) and acid detergent lignin (ADL) contents of rice straw were determined before and after 10 days of fermentation. Fermentation has significant (P < 0.01) effect on NDF, but not ADF and ADL contents. Addition of urea as nitrogen source significantly reduced (P < 0.01) the NDF and hemicellulose contents of fermented rice straw. Cellulose content of the rice straw was not affected (P > 0.05), but crude protein (CP) increased significantly (P < 0.01) after fermentation. In vitro gas production technique was used to evaluate the effect of the biological treatment on activity of rumen microorganisms. Fermentation of rice straw using A. niger significantly reduced total gas production (P < 0.01), DM disappearance (P < 0.01) and acetate, propionate and  total volatile fatty acids (VFA) production (P < 0.05). Results of the present study showed that solid state fermentation of rice straw using A. niger reduced lignocellulose content, but has negative effect on microbial activity in the rumen ecosystem, presumably due to antagonistic activity of A. niger, or other intermediate products from the fermentation, on the rumen microorganisms.Key words: Aspergillus niger, biomass, solid state fermentation, biological treatment, in vitro gas production