| Distiller’s grains are an important renewable resource in industrial production.If not handled properly,it will not only pollute the environment,but also be a waste of resources.If the distiller’s grains can be processed into feed,it can not only alleviate the shortage of feed resources but also improve the ecological environment.High cellulose content and refractory degradation are the main factors restricting the utilization of distillers grains feed.This paper mainly studies the screening of cellulose-degrading bacteria,liquid fermentation,solid fermentation conditions,enzymatic properties and degradation rate of distiller’s grains,in order to achieve the purpose of efficiently degrading distiller’s grains and provide a theoretical reference for the resource utilization of distiller’s grains in my country.Using sapropelic soil,distiller’s grains,dakoji and fungus bran as bacterial sources,160cellulose-degrading bacteria were isolated and purified at 30 ℃,37 ℃ and 50 ℃.Four strains with high cellulase activity were obtained by primary screening of Congo red and rescreening of enzyme activity.By morphological observation,physiological and biochemical identification and molecular biological identification,M3005 was identified as Trichoderma Asperellum and M5011 was identified as Thermoascus Aurantiacus.Strain M3709 was Aspergillus Niger,and strain X3738 was Bacillus amyloliquefaciens.After optimizing the enzyme production conditions of liquid fermentation by single factor and orthogonal experiments,the CMC enzyme activities of strains M3005,M5011,M3709 and X3738 were 7.93 U/m L,10.78 U/m L,11.26 U/m L and 5.01 U/m L,respectively.Increased by 9.50%,20.45%,64.38%,5.25%;The enzyme activities of filter paper were 3.01U/m L,1.19 U/m L,2.35 U/m L and 1.36 U/m L,which were increased by 5.60%,16.67%,78.03% and 18.26%,respectively.After optimizing the enzyme production conditions of solid fermentation by single factor and orthogonal experiments,the CMC enzyme activities of strains M3005,M5011,M3709 and X3738 were 128.20 U/m L,165.21 U/m L,133.59 U/m L and 74.51 U/m L,respectively.The enzyme activities were increased by 70.41%,125.67%,67.34%,and 13.36%,respectively;the filter paper enzyme activities were 63.55 U/m L,58.13 U/m L,49.26 U/m L,and 13.72 U/m L,respectively,and the filter paper enzyme activities were increased by110.85%.,47.46%,86.38%,25.99%.The enzymatic properties of the strain were studied.The optimum reaction temperature of crude enzyme solution of strains M3005,M5011,M3709 and X3738 were 55 ℃,65 ℃,60 ℃ and 45 ℃,respectively,and the optimum reaction p H was 6,5,5 and 6,respectively.In terms of reaction temperature and p H,strains M3005,M5011,M3709 and X3738 were favorable for enzymatic reaction under high temperature and acidic environment.A group of complex bacteria M5011+M3709 with high enzyme activity was screened by antagonism and enzyme activity assay.The CMC enzyme activity was 146.70 U/m L,increased by 5.71%,and the filter paper enzyme activity was 56.09 U/m L,increased by40.23%.The degradation effects of strains M3005,M5011,M3709,X3738 and complex bacteria M5011+M3709 on distiller’s grains were investigated: the degradation rates of distiller’s grains were 24.67%,36.94%,29.91%,13.60% and 38.35%,respectively.There was no significant difference between strain M5011 and compound strain M5011+M3709 in distiller’s grains degradation effect(P>0.05).Considering economic cost,single strain M5011 was selected as the optimal strain. |
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