| To promote the rapid decomposition of corn straw returned to fields in frigid regions,the present study,the microbial consortia suitable for frigid region with straw degradation at low temperature were screened by restrictive transgenerational cultivation and cold domestication technology from the 55 samples that different ecological regions.Then the biological characteristics,microbial composition,corn straw degradation activity,adaptability and stability of microbial consortia were investigated,so as to provide microbial decomposer in frigid region of northern China.Furthermore,the decomposition mechanism of M44 was evaluated by metagenomic sequencing technology.Meanwhile,straw returning degradation experiments in different ecological regions of Inner Mongolia were carried out to verify the application effect of straw degradation microbial consortium.The main results were as follows:1.Microbial consortia with high efficiency degradation straw at low temperature were screened out.9 groups of microbial consortia were isolated from the collected humus,corn straw returned soils,cow and sheep dung from different ecological regions of Inner Mongolia by enrichment cultivation and low-temperature restriction subculture technology.Taking the degradation ratio and enzyme activities as indicators,the microbial consortium M1,M2,M14,M36 and M44 with the potential to degrade corn straw stably and efficiently were obtained through primary screening and re-screening.In which,the M1 mainly included Pseudomonas,Trichococcus,Enterococcus,Devosia,the M2 was consist of Brevundimonas,Enterobacter and Enterococcus,the M14 mainly contained Pseudomonas,Enterococcus,Brevundimonas and Azospirillum,the M36 mainly included Trichococcus,Enterococcus,Pseudomonas,Nocardioides,Sphingomonas,and dominant genera of the M44 were Pseudomona,Brevundimonas,Acinetobacter and Azospirillumr.2.Efficiency degradation characteristics of corn straw at low temperature was identified.The microbial consortia went into logarithmic growth phase in the early stage of culture,and could p H self-adjustmenta at 15 ℃ conditions.With the decomposition of straw,filter paper enzyme,endoglucanase,xylanase,laccase and lignin peroxidase of microbial consortium reached the highest in the culture 5th or 10 th day,and the degradation rate of corn straw and lignocellulose showed the characteristics of fasert in the early stage and slowly in the later stage.Moreover,microbial consortia remained relaticely stable in straw degradation characteristics and microbial composition under temperature 10～15 ℃,p H 6～8,liquid loading 30～50 m L conditions and differen subgenerations.Among them,the microbial consortium M44 showed excellent stability and adaptability to volatile environment,had good application potential.3.Degradation mechanism of microbial consortium M44 with high efficiency degradation straw at low temperature was evaluated.In the early stage(1～14 d),filter paper enzyme,endoglymediase and xylanase activity greatly increase,and the Alkyl-C and di-OAlkyl-C decreased significantly,mainly decomposed cellulose,hemicellulose and other easily decomposable substances.And in the later stage(14～28 d),the activities of laccase and lignoperoxidase increased,and Aryl-C and Carbonyl-C increased significantly,mainly degrading lignin,wax,tannin and other refractory substances.Based on metagenomic analysis,cellulose and hemicellulose were mainly decomposed by associated degradation enzymes that endocut β-1,4-glucanase,exocut β-glucanase and β-glucosidase Glycanase,β-1,4-mannosidase,endonuclease-β-1,4-xylanase secreted by Pseudomonas,Delftia,Leclercia,Raoultella,Sphingobium,Microbacterium,and lignin was mainly decomposed by lignin active enzymes which laccase,manganese peroxidase,lignin peroxidase,cellulose dehydrogenase and others secreted by Pseudomonas,Enterobacter,Delftia,Chryseobacterium,Sphingobium,Stenotrophomonas.It can be seen that the degradation of lignocellulose is the result of the joint action of various enzymes secreted by various microorganisms.4.Application effects of microbial consortium M44 with high efficiency degradation straw at low temperature were expounded.Straw returning combined with microbial decomposetr M44 could significantly increase the straw and lignocellulose decomposition rate,nutrient release ratio in 0～210 d.At the end of decomposition,the degradation rates of corn straw,cellulose,hemicellulose and lignin were processed by RM treatment at each test site were 58.13%～62.53%,39.38%～47.71%,39.91～49.96%,30.97%～38.79%,respectively,and 3.82～8.29,4.24～8.54,4.45～6.97 and 4.93～10.84 percentage points higher than the control.In addition,the soil enzyme activities in 0～45 cm soil layer of each test site could be improved by applying degrading agent of each test site,and the activities of soil catalase,urease,alkaline phosphatase,sucrase and cellulase in 15～30 cm soil layer increased by5.84%～9.37%,1.80%～8.47%,3.61%～10.70%,3.67%～11.48% and 6.43%～17.31%respectively than the control. |
PDF Full Text Request