Screening And Evaluation Of Strains With Cellulose Degradation Function In Composting

China is a large agricultural production country.With the continuous improvement of agricultural production,the production of crop straws has also increased year by year,which has also brought problems such as environmental pollution caused by the irrational use of crop straw resources.Aerobic composting has been widely used and studied as an effective method to treat crop waste and make it resource-free and harmless.In recent years,inoculation of beneficial bacteria has been used to promote the temperature of the compost,accelerate the compost maturation rate,and improve the compost quality to a certain extent.Because different composting materials are different,their composition and properties are also different,so the microbial agents added in various composts are also different.However,despite this,many problems related to the composting time and compost quality of crop straw compost have not yet been resolved.In this study,a strain capable of efficiently degrading cellulose was selected from corn straw compost,and the strain was identified and the cellulose-related enzyme activity was quantitatively determined.Corn straw and Chinese cabbage were used as compost materials./N is about 57 and the water content is about 73%.A 12-day multiplex composting experiment was performed.The changes of various parameters in the multiplex composting experiment were used to evaluate the effect of the strain on the composting process.The effect reflects the application effect of inoculated strains on compost.The main research results are as follows:(1)Based on corn straw compost samples,43 isolates with cellulose degradation function were obtained by Congo red staining method.Through measurement of cellulose degradation circle and filter paper disintegration experiment,it is preferable to obtain 3 strains with cellulose degradation function,which are respectively numbered as C31,C37,and GD16.(2)Gram staining of strain C31 is positive,phylogenetic analysis shows that C31 has the highest similarity to Streptomyces drozdowiczii,reaching 99.36%;Gram staining of strainC37 is negative,and phylogenetic analysis shows that it is related to Streptomyces corchorusii has a close relationship,with a similarity of 99.28%;the strain GD16 is positive for Gram staining,and peacock green staining shows spore production.GD16 has been identified to have a close relationship with Paenibacillus pabuli.The similarity is 99.54%.(3)The results of measuring cellulase activity by DNS method showed that the cellulase activity of strain C31 was the highest under 37? culture conditions,which could reach 4.8U/mL.Among filter paper enzyme activities,C31 has the highest filter paper enzyme activity,which can reach 3 U/mL.Among the xylanase activities,GD16 has the highest xylanase activity,which can be as high as 23 U/mL.(4)The results of multiplexing composting experiments showed that inoculation of the same volume of mixed bacterial solution of three strains into the compost can accelerate the compost maturation rate and shorten the compost cycle.After inoculating the bacterial solution,the treated group reached a maximum temperature of 66? on the first day.At the same time,the stack temperature of the control group was 57?,and the difference between the two treatment groups was 8?.The treatment time of the inoculated group increased by 1day in the high temperature period compared with the control group without inoculation;the pH of the compost reached a stable value faster than the control group and maintained the pH at about 8.5;compared with the control,the Organic matter content(OM)decreases rapidly.The OM content of the treatment group on the 12 th day after inoculation was significantly lower than that of the control(P <0.05);the seed germination index(GI)of the treatment group rose faster than that of the control group,and the GI of the inoculation treatment group reached on the 4th day.The GI value of the control group reached 80% on the 6th day;at the end of composting,the GI value of the treated group reached 118%,while the GI of the CK was 103%.The GI value of the treated group was higher than that of CK.Out of 15.0%.(5)Determination of cellulose and hemicellulose of the compost sample during the composting process showed that the cellulose degradation rate of the treatment group samples was 21.1%,the hemicellulose degradation rate was 7.2%,and the control group cellulose degradation rate was 10.9%.The degradation rate was 3.2%.Compared with the control group,the treatment group of the final inoculation bacterial solution of the final compost product increased the cellulose degradation rate by 10.2%,and the hemicellulose degradationrate increased by 4.0%.(6)At the completion of composting,although the total nitrogen(TN),total phosphorus(TP),and total potassium(TK)in the compost samples did not reach a significant level of difference,the final treatment group compared with the start of composting.Total nitrogen in the compost product increased by 14.52 g/kg,and the final nutrient content was increased compared with the control group.In summary,in this study,by recombining the cellulose-degrading bacteria C31,C37,and GD16 which isolated from the compost material into the compost again,the compost temperature could be significantly increased,the start of the compost could be accelerated,and the high temperature period of the compost could be prolonged.Ultimately,the compost cycle was shortened and compost quality was improved.