Screening And Identification Of Cellulose Degrading Strains And Optimization Of Enzyme Production Conditions

In recent years,limited reserves of fossil fuels and global climate change have sparked a great interest in finding alternative sources of renewable biomass.Lignocellulosic biomass,rich in cellulose,as a renewable raw material for biorefinery processes,has great potential.However,lignocellulosic biomass is often difficult to effectively hydrolyze due to its high degree of lignification and crystal structure,leading to waste of material resources and environmental pollution.Therefore,screening cellulose efficient degradation of the strain is to reduce the cellulose waste of a green,cheap and effective an important way.In this experiment,soil samples collected from Yunnan Wenshan?Harbin Botanical Garden other places of rotten wood,straw accumulation.Seven strains of bacteria capable of producing clear circles were screened by liquid culture medium enrichment culture,dilution coating,crossed separation and Congo red identification culture.The seven strains were subjected to liquid fermentation re-screening to obtain two strains with high enzyme activity Bacteria,respectively,named N6,WG10.The strain N6 was identified by morphological and molecular biology and finally identified as Achromobacter.The results showed that the activity of carboxymethylcellulose(CMCase)was 3.918U/ml,the activity of filterase was 1.902U/ml,P-glucosidase activity(P-Gase)was 2.173U/ml.The strain WG10 was identified by morphological and molecular biology and finally identified as Penicillium.Enzyme activity assay showed that the activity of carboxymethylcellulose(CMCase)was 4.021U/ml,the activity of FPase was 2.334U/ml,the activity of ?-glucosidase(?-Gase)was 3.497U/ml.The effects of sole carbon source,culture time,initial pH value and culture temperature on the enzyme activities of strains N6 and WG10 were investigated by single factor experiment.The results showed that the strain N6 had the highest activity when it was taken corn stalks as the sole carbon source,the initial pH of the culture medium was 6.0,the culture temperature was 40 ?,and the incubation time was 72 h.Under these conditions,the activity of carboxymethylcellulose(CMCase)was15.932U/ml,the activity of FPase was 8.445U/ml,and the activity of ?-glucosidase(?-Gase)was 10.164U/ml,respectively,compared with the enzyme activity before optimization increased by 2.96 times,2.62 times,1.91 times.The strain WG10 had the highest activity when it was taken corn stalks as the sole carbon source,the initial pH of the culture medium was 8.0,the culture temperature was 35 ?,and the incubation time was 48 h.Under these conditions,the activity of carboxymethylcellulose(CMCase)was 16.956U/ml,the activity of FPase was 8.512U/ml,and the activity of ?-glucosidase(?-Gase)wasll.689U/ml,respectively,compared with the optimization before the increase of 3.33 times,3.38 times,4.37 times.The ability of strain N6 and WG10 to degrade straw cellulose was studied.Two strains were subjected to liquid culture for 3,5,7 and 9 days.The degradation rate of straw was 9.53%,15.07%,25.39%and 65.07%respectively.The degradation rate of straw in strain WG10 was 17.98%,22.62%,35.01%and 79.17%respectively,the results showed that the two strains of straw have a higher ability to degrade.