| The northeast region is the main grain producing area and is rich with agricultural resources in China.Straw is a by-product of crops remaining after the traditional agriculture,because the level of agricultural technology is relatively lagging behind and farmers’ ideology is weak,a large amount of straw is wasted every year,even burning in the field causes serious air pollution.Therefore,it is of great significance to deal with the problem of straw degradation and to solve the problem of energy utilization and environmental pollution.The main component of straw is lignocellulose.It is widely distributed in nature.It is one of the renewable resources of great storage.But the utilization of straw is very low because these resources are difficult to degrade under natural conditions.In order to find the efficient straw degradation bacteria,improve that degradation effect of the straw and shorten the decomposition time of the straw.High efficient straw degrading bacteria were obtained from rotting straw,cow dung,deer dung and soil,and the degradation ability of single and compound fungicides to straw was studied,which provided theoretical basis for the effective utilization of straw solid waste and straw resources.In this paper,we screened and identified the efficient straw degrading bacteria.The indoor straw degradation and field composting test were combined to fully examine the effect of bacteria in natural environment on the degradation of straw,so as to achieve the purpose of practical application.The main results are as follows:(1)Through Congo red staining and filter strip degradation test,4 strains with high cellulose degradation ability were selected,including 2 fungi and 2 bacteria.G1 and CMC-red could degrade the filter paper into a paste in 10 d.Two bacteria with strong cellulose degradation ability were analyzed by 16 SrDNA sequence,and the initial identification of CMC-red was Massilia arvi,and the strain CMC-I was Flavobacterium banpakuense.(2)Straw fermentation experiments of single strain and compound strain were carried out in laboratory to determine the degradation effect of each strain on straw.The activity of CMC and FPA of FH reached the maximum on the 6th day of fermentation.Comprehensive comparison of CMC activity and FPA activity in single strain,G1 had the highest activity and CMC-I had the lowest activity.At the end of straw fermentation,the degradation rate of cellulose reached 43.16% by FH,27.89% higher than CK.The highest degradation rate of cellulose by G1 was 20.96% higher than that of CK.After 30 days of fermentation,the weight loss rate of CK was only 8.21%.Among the single strain,G1 had the best degradation effect on straw,and the weight loss rate was 44.21%.The degradation rate of FH was 48.26%,4.05% higher than that of G1.Therefore,the degradation effect of FH strain was the best during the degradation of indoor straw,and The degradation efficiency of G1 strain is the best in single strain.(3)The straw treated with FH,G1 and CKT after composting in the field were dark brown and loose and easy to break.Scanning electron microscope(SEM)was used to observe the micro-structure of straw,and the degradation of straw was severe,and the degradation of straw was especially obvious.The moisture content of CKT,FH and G1 were relatively low at 60 days after composting.The total nitrogen content of different treatments decreased and then increased.The change trend of organic matter content in each treatment showed a downward trend,and then tended to be stable.The changes of G1,L1 and CKT were larger than CK.After 60 days of composting,the germination index of seeds of each treatment was higher than that of CK,which indicated that the effect of compost maturation was better and the toxicity to plants was lower.The identification of fungal communities in different compost samples showed that the number of Ascomycota and Basidiomycota was the highest.The fungal diversity of CKT samples was the highest,followed by FH,while that of L1 samples was the lowest.The composition of bacterial communities in the compost samples at the Phyllum level was similar.The proportion of Proteobacteria in CKT was 62.46%.CMC-I and CMC-red in the Bacteroidetes accounted for 39.5% and 37.83%.The Shannon index and Simpson index of CMC-red were 8.471 and 0.994 respectively,and the microbial diversity was the highest. |
