Study On The Construction Of High Efficiency Rice Husk Degrading Complex Bacteria And Their Degradation Effect

In this paper,the organic mulch and top soil of Phyllostachys violascens woodland were used as the research objects,and the cellulose medium with three different carbon sources as the substrate was used for screening and identification of high-efficiency cellulose degrading bacteria;the cellulose degrading complex bacteria were constructed and their enzyme-producing conditions were optimized,and the degradation effect of the complex bacteria on the grain hulls of Phyllostachys violascens woodland mulch was investigated.The main research results are as follows.(1)184 strains of bacteria were isolated from the bamboo woodland and 148 strains were screened for cellulose degradation using three different carbon sources as substrates.62 strains with strong degradation ability were screened,including 15 strains using microcrystalline cellulose as carbon source,23 strains using D-salicin as carbon source and24 strains using sodium carboxymethyl cellulose as carbon source.(2)The enzymes and their enzyme activities of cellulose degrading bacteria screened with different carbon sources were different,and the strains screened with microcrystalline cellulose as the carbon source produced exonuclease with enzyme activities of 2-19 U/m L;the strains screened with D-salicyloside as the carbon source produced β-glucosidase with enzyme activities of 3-18 U/m L;the strains screened with sodium carboxymethyl cellulose as the carbon source produced endonuclease with enzyme activities of 3-20 U /m L.(3)The degradation bacteria screened from different carbon sources were subjected to a 3-factor 2-level orthogonal test,and the constituent strains of the composite flora were C7,W3 and D23;the enzyme-producing conditions of the composite flora were optimized,and the optimum conditions for enzyme production by the composite flora HB were determined as the mixing ratio of C7:W3:D23=1:1:1,the incubation time of 4 d,and the incubation temperature of 30℃;the optimized composite flora had a higher enzyme activity on the filter paper The disintegration rate of the optimized composite colony increased by 9.62%,6.19%and 7.87%,respectively,compared with that of the single strain C7,D23 and W3.(4)The complex bacteria HB showed better enzyme activity,with CMC enzyme activity reaching 28.8403 U/m L and FPA enzyme activity reaching 10.0319 U/m L by 30 d.In the potting bowl simulation test,the degradation rate of hulls by the complex bacteria HB was 40% higher compared with the control,which increased the soil temperature and caused changes in the surface structure of hull particles such as disintegration,and the reduction of hull material composition was Significantly,cellulose was reduced by 26.53%,hemicellulose by 11.00% and lignin by 22.33%.