| Straw cellulose is the most abundant renewable organic carbon resource in nature.Under natural conditions,due to its complex structure,it is not easy to be degraded,resulting in slow decomposition.The straw returning process will affect the rooting and survival of crops,thus limiting The process of returning straw to the field.The process of returning land.In order to promote the rapid decomposition of straw,screening microorganisms to degrade straw has become a research hotspot in recent years.Under the conditions of dry farmland in the north,when using microbial inoculants,the moisture content has also become a limiting factor for biodegradable straw.Therefore,in order to make better use of cellulase produced by microorganisms to treat straw and accelerate the decomposition efficiency of straw returning to the field,research and development of straw bio-rapid technology suitable for dry farmland in the north,to meet the technology of straw returning to the field under different environmental conditions Demand also has certain economic and social benefits.Using straw powder plates,73 strains of cellulose-degrading bacteria were screened and separated from soil,litter compost and silkworm excrement.The straw degradation medium was used to determine the wheat straw degradation ability of the selected strains.Finally,3 highly efficient cellulose-degrading strains were obtained,including 2 fungi(M-2,M-17),1 bacteria(X-1),and straw weight loss The rates are 34%,35% and 25% respectively.Microscopic identification results showed that M-2 was Aspergillus,M-17 was Penicillium,and X-1 was Gram-positive bacteria.The filter paper enzyme activities of the three strains of degrading bacteria were measured,and their maximum filter paper enzyme activities were 48.00 U / m L,30.00 U / m L,and 21.60 U / m L,respectively.Na Cl was used to carry out solid drought tolerance on strains M-2,M-17 and Aspergillus niger M-9(due to the small colony of strain X-1,which could not be determined in the plate.Sexual domestication.After acclimation,the growth of strains M-2 and M-17 at a Na Cl concentration of 1.0 mol / L is affected to a certain extent,and the growth rate slows down.The growth rate of strain M-9 had no significant effect at the concentration of 1.0mol / L.In the presence of high concentration(1.0 mol / L)of Na Cl,the cellulase activity of the strain after domestication was significantly improved,and the endoglucanase(45.80 U / m L)and ? of the strain GM-2 after domestication-Glucosidase(24.05 U / m L)is higher than the enzyme activity of the original strain M-2 under initial conditions,but exoglucanase(22.77 U / m L)is lower than the original strain M-2;the strains GM-9 and GM-17 The glucanase activity was higher than the original strain,and the exoglucanase and ?-glucosidase activities were reduced.The straw degrading ability of the original strain after acclimation was determined with 30%,40% and 50% moisture content of the straw fermentation medium.The strain GM-2 had the highest straw degradation rate of 18.5%,30.5% and 36.5% respectively.The strains M-2,M-17 and X-1 obtained by screening were domesticated with liquid drought tolerance using polyethylene glycol 6000.After acclimation with gradient concentration,the growth of strains M-2 and M-17 was significantly inhibited when the concentration of polyethylene glycol was higher than 25%,and that of strain X-1 was inhibited when the concentration of polyethylene glycol was higher than 15%.After acclimated by gradient concentration,polyethylene glycol has a greater impact on the enzyme activity of microorganisms,and the cellulase activity of strains PM-2,PM-17 and PX-1 is lower than that of the original strain.The straw degrading ability of the strains after acclimation was measured in the fermentation medium of straw section with 30%,40% and 50% moisture content.Under the condition of 30% moisture content,the straw weight loss rate of strain PM-17 was 13.00% higher than that of PM-2 And PX-1,under 40% and 50% water conditions,the straw weight loss rate of strain PM-2 was 36% and 34%,respectively,which were significantly higher than those of strains PM-17 and PX-1.The biofilm fermentation of microorganisms was studied using luffa crumbs,and the ability of M-17 strains to produce enzymes and straw degradation in the presence of 25% polyethylene glycol was explored.In the presence of high concentration of PEG6000,the biomass of strain M-17 in biofilm fermentation(0.428 g/L)was found to be superior to that in deep fermentation(0.301 g/L),the endoglucanase,exoglucanase and ?-glucosidase enzyme activities were 17.57,10.34 and 14.04 U / m L,respectively,which were better than those of the enzyme in the deep fermentation.By measuring the degradation rate of wheat straw under different moisture content,the strain inoculated on the loofah has better resistance to stress,and can still grow rapidly under the condition of lack of moisture,under the conditions of 30%,40% and 50% moisture The weight loss rate of straw reached 17%,19% and 25% respectively within ten days,and the degradation rate of wheat straw was significantly better than that of deep fermentation(5%,18.5% and 16%).The domesticated strain was combined with the original strain and the laboratorypreserved yeast and Trichoderma viride at a ratio of 2: 1,and then inoculated into bran to prepare a fungus preparation.The pot straw degradation experiment with different moisture content was conducted on wheat straw.After 60 days,the straw was obviously weightless,the volume became smaller,and the straw became softer.Through measurement,under normal irrigation and reduced irrigation,the weight loss rate of wheat straw reached 51.5%,47.7% and 43%,respectively,and the domesticated mixed fungicide was significantly better than the commercially available non-domesticated fungicide;with no added fungicide Compared with the treatment,the weight loss rate of straw is significantly different. |
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