ABSTRACT
Characters of one Candida intermedia yeast strain which isolated from nature can produce ethanol from xylose-fermenting been systemic studied. In conditions 28?C, 120 r/min, 72 h, it can produce 6.480 g/L ethanol from 7% xylose and 43.70% theoretical production of ethanol from 3% xylose. It can produce up to 21.225 g/L ethanol when incubation time prolong to 156 h from 8% xylose. It also can ferment 13% glucose produce 47.647 g/L ethanol and reach 76.90% of theoretical ethanol production, respectively. Compared to CK, ethanol productivity can be improved 9.91% when add 8% xylose in three times as 3%, 2% and 3%, respectively. Glucose can be first utilized in the mixture sugar medium. When the ratio of xylose vs. glucose is 3:1in mixture sugar, the productivity of ethanol can be improving 25%.
ABSTRACT
Response surface analysis (uniform precision of central composite design, SAS 9.1.3 software) was applied to optimize the four major factors (ratio of soybean meal to water, enzyme quantity, fermentation time and inoculation quantity) for soybean meal solid fermentation. According to the change of the hydrolyzation degree of soybean protein, the equation of polynomial regression was established between those factors and the response. The result showed that the optimum condition included as follows: ratio of soybean meal to water 1∶1.00,enzyme quantity 2.55%, fermentation time 65h and inoculation quantity 1.00%. Under the optimum level, the degree of hydrolyzation reached 13.3%, which increased 56% over pre-optimization.
ABSTRACT
In this study, Streptomyces avermitilis Bjbm0006 which produces four avermectin B components was used as an original test strain. A replacement plasmid containing a gene cluster bkdAB (branched-chain alpha-keto acid dehydrogenase gene) involved in the biosynthesis of avermectin B in S. avermitilis Bjbm0006 was constructed by means of PCR technique and then named as pHJ5821 (pHZ1358::bkdAB&erm). A recombinant strain Bjbm5821 was obtained after the gene cluster was interrupted by double crossover. This strain was tested in laboratory conditions and analysed by PCR using the total DNA as template. The HPLC analysis showed that the strain Bjbm5821 synthesized the same 'a' components Bla and B2a as the original strain did. However, It lost the ability for the production of 'b'components for example B1b and B2b. A novel compound was detected in fermentation products. The results of present study suggests that the production of gene cluster bkdAB may play a main role similar to alpha-ketoisovaleric acid dehydrogenase in the pathway of avermectin synthesis.
Subject(s)
3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide) , Genetics , Ivermectin , Metabolism , Recombinant Proteins , Genetics , Streptomyces , GeneticsABSTRACT
14 strains were isolated from pits sludge by anaerobic cultivation,two Clostridium butyricum strains were identified by physiological and biochemical experiments and the sequence analysis of 16S rDNA.The physiological characteristics and security of Clostridium butyricum B1 were studied,in vitro research indicated it was tolerant against low pH,bile concentration and antibiotics and has antagonism effects against pathogens.