| This study was conducted to screen the strains from the soil, cattle rumen,which were obtained with cottonseed meal free gossypol degradation, to study the fermented cottonseed meal degradation mechanism of free gossypol, fermentation process of cottonseed meal.The results of the study would provide good technical reference for the detoxification of cottonseed meal.Experiment I: Isolation and Identification of Strains for degrading free gossypol from different habitatsThis study aimed to screen out the strains with high efficiency of free gossypol detoxification from the cotton soil and cattle rumen fluid using the nutrient agar supplemented with cottonseed meal.The results showed that two strains YRS and QRS were screened out from the soil,the content of free gossypol reduced from 560.05 mg/kg to52.50 mg/kg and 90.33 mg/kg,and the detoxification efficiencies were up to 90.63% and83.87%, respectively. LH3 Y and R1.0320 which screened out from our lab, the content of free gossypol reduced from 560.05 mg /kg to 68.05mg/kg and 120.09 mg/kg, the detoxification efficiencies were up to 87.85% and 78.56%,respectively. The YRS strain was identified as the Lactobacillus plantarum by the morphology and biochemical characteristic.Experiment II: Detoxification of different fermentation and its process parametersThe process parameters for fermentation detoxification was optimized,which included water ratio, inoculation, fermentation temperature and fermentation time.The result showed that the single strain fermentation was superior to that of mixed cultures, the best strain was YRS and the degradation rate of free gossypol was 90.52%.All the groups had a certain degradation of bound gossypol,and the QRS group reached the maximum amount up to 898.17 mg/kg.The optimum fermentation conditions for gossypol detoxification were water ratio of 1: 0.8,inoculum level 3% v/w, incubation temperature at 33℃,incubation period of 60 h.With the process optimization, the virus-free rate of YRS strain increased from 90.63% to 95.21%.Experiment III: The fermented effect of uncooked cottonseed meal with different strainsThis study was aimed to study the fermentation with uncooked cottonseed meal,usingthe single and double strains of YRS,QRS,R1.0320,LH3 Y and DFL,then researching the effect of detoxification rate and the improvement of protein peptide and crude fiber. The results showed that fermented detoxification rate of uncooked cottonseed meal was generally low, cottonseed meal protein peptide had improved and crude fiber degraded well, which QRS+ LH3 Y group had the best fermented effect, with the fermentation detoxification rate of 35.56%, a 1.62 percent increase of crude protein, and the mall peptides increased from the original 8.40% to 28.68%, the NDF and ADF of the cottonseed meal degradation rated up to 16.76% and 18.85%.Experiment Ⅳ: Factors affecting the effect of compound fermented cottonseedThe objective was to study the effect of different carbon sources, sodium carbonate,ferrous sulfate, ammonium sulfate on the reduction of gossypol level during solid substrate fermentation of uncooked cottonseed meal.The results showed that adding glucose, sucrose,lactose and other carbon sources in cottonseed fermentation substrates could not improve the composite fermented raw cottonseed detoxification rate;The cottonseed substrate supplemented with 0.5% sodium carbonate could significantly reduced the content of free gossypol than the other groups(P<0.05), and the detoxification rate reached up to43.03%;The effect of cottonseed substrate added with 0.5% of ferrous sulfate was well,and which could significantly reduce the content of free gossypol than the control group(P<0.05),the detoxification efficiency up to 61.86%,and which had not affected the degradation of protein. The addition of ammonium sulfate was 1.5%,and the detoxification rate reached up to 55.29%. |
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