Screening Of A Psychrotrophs And Its Effect On The Decomposition Of Corn Stover

Aerobic composting is one of the solutions to resource utilization of crop straw,which can rapidly transform agricultural waste and the resulting product is used as a soil conditioner or organic fertilizer.However,in northern areas of China,the low temperature environment limits the application of aerobic composting technology due to the low ambient temperature in winter,resulting in a slow start of straw compost fermentation temperature in winter,and even the microorganisms in the pile stopping their activities.In this study,to solve the problem of difficult temperature start of straw aerobic composting in low temperature environment,the microbial strains that can grow normally in low temperature environment and have cellulose degradation ability were screened from decaying straw in farmland and its surrounding soil,and optimized by using response surface methodology to visually discern the optimization area and determine the best culture conditions for this strain.At the same time,it was inoculated as an inoculant to investigate its effects on the physicochemical properties,bacterial community structure composition and succession in the process of composting corn stover,providing a theoretical basis and scientific basis for the preparation of low-temperature straw aerobic composting initiator in northern cold regions.The following main results were obtained in this study:(1)Lignocellulolytic Psychrotroph bacteria were screened from soil,isolated and purified by Congo red staining method,and named as LYG-01.The strain was identified as Lelliottia sp.by morphology,physiology and biochemistry as well as 16 S r DNA results of the strain.The results of response surface analysis showed that the optimal culture conditions for the strain were at p H 6.8,incubation temperature of 24.18℃ and inoculum size of 3.12% under laboratory conditions.(2)Inoculation of the strain into corn stover for composting effect test,the results showed that the test group entered the high temperature stage on the first day and lasted for 8 days,while the control group entered the high temperature stage on the fourth day and maintained it for only 5days.The electrical conductance(EC)value of the test group met the requirement of biotoxicity(3.7 m S/cm).The carbon to nitrogen ratio(C/N)and seed germination index(GI)values were used to determine the degree of pile decay,and the decay efficiency of the experimental group was better than that of the control group.The wave spectroscopy analysis showed that the straw structure was destroyed as the composting proceeded.At the same time,inoculation accelerated the straw degradation.(3)16S r DNA identification of compost samples at each stage of composting showed that inoculation made changes in the composition and function of the compost community,and inoculation increased the diversity and abundance of bacterial communities in the compost,making Enterobacter,Thermobacillus,Pseudomonas and other pro-compost fermentation strains dominate in the compost.Functionally,the carbon cycling function is the main function in the composting process.The inoculation promoted the degradation of organic matter in the compost pile and played a facilitating role in composting.(4)Using Redundancy analysis(RDA),the relationship between environmental factors and bacterial communities was comprehensively analyzed,indicating that temperature and C/N were the main environmental factors driving the succession of bacterial communities in the pile.