cellulase and n-hexane

The production of cellulases from Stachybotrys microspora strain (A19) has been improved by fed-batch fermentation on Avicel cellulose 10 mg/ml. An endoglucanase EG2 was purified to homogeneity. This cellulase has a molecular mass estimated to 50 kDa when analyzed by a denaturant gel electrophoresis. It exhibited an optimal activity at 50 °C, pH 7.0 and 0.85 M NaCl. Specifically, these results show the thermo-active, alkali-tolerant and halo-tolerant properties of EG2. In addition, this endoglucanase showed its highest activity on barley-β-glucan, compared to the CMC. Moreover, it was less active on Avicel cellulose. Furthermore, the EG2 activity was stimulated in the presence of EDTA, urea and β-mercaptoethanol whereas it was reduced in the presence of SDS. This cellulase was highly stable in the presence of organic solvents such as acetone and n-hexane. TLC showed that the main hydrolysis products from EG2 were cellobiose and glucose. This fungal endoglucanase could be potentially important in the conversion of grass-derived biomass into fermentable sugars.

Topics: Acetone; Cellulase; Enzyme Stability; Fungal Proteins; Hexanes; Stachybotrys

Rice straw hydrolysate was used as lignocellulose-based carbon source for Chlorella pyrenoidosa cultivation and the feasibility of in situ biodiesel production was investigated. 13.7 g/L sugar was obtained by enzymatic hydrolyzation of rice straw. Chlorella pyrenoidosa showed a rapid growth in the rice straw hydrolysate medium, the maximum biomass concentration of 2.83 g/L was obtained in only 48 hours. The lipid content of the cells reached as high as 56.3%. In situ transesterification was performed for biodiesel production. The optimized condition was 1 g algal powder, 6 mL n-hexane, and 4 mL methanol with 0.5 M sulfuric acid at the temperature of 90°C in 2-hour reaction time, under which over 99% methyl ester content and about 95% biodiesel yield were obtained. The results suggested that the method has great potential in the production of biofuels with lignocellulose as an alternative carbon source for microalgae cultivation.

Topics: Biofuels; Biomass; Biotechnology; Carbon; Cellulase; Chlorella; Chloroform; Esterification; Hexanes; Hydrolysis; Lipid Metabolism; Methanol; Oryza; Plant Oils; Solvents; Temperature; Time Factors; Waste Products

Single cells prepared from autoclaved soybeans and cellulase treatment of the cells were effective in digesting the cell walls of and extracting the oil from soybeans. The first cell wall of the soybean single cell was completely removed using cellulases; the thin and transparent second cell wall of the cell was swollen. Oil in the cell formed spherical or hemispherical oil drops, and oil leaking from the oil bodies was observed. The oil was almost retained within the second cell wall. Water-extractable substances were obtained at approximately >60% of the weight. Flotation of oil drops by centrifugation was easily done. Ambient n-hexane extraction was also possible; however, residual oil remained in the oil bodies. Protease or peptidase digested the structure of the oil bodies; however, separation of the oil and the hydrolysates was impossible. The oil from the oil bodies was obtained effectively (>85%) by pressing the single cells and/or cellulase-treated single cells.

Topics: Cell Wall; Cellulase; Centrifugation; Endopeptidases; Glycine max; Hexanes; Peptide Hydrolases; Pressure; Soybean Oil; Trypsin