Screening and characteristics analysis of straw-degrading bacteria

CHENG Lin; WANG Zongya; HUANG Shuangshuang; WU Hongyan; LI Ruichao

doi:10.16861/j.cnki.zggc.2024.0520

Abstract：In order to screen out the microbial agents that efficiently and rapidly degrade straw,and provide a theoretical basis for the fertilization of straw returning to the field.The dominant strain XJ-132 was screened from 160 straw-degrad-ing bacteria by enrichment culture.The antagonism of XJ-132 strain and the mechanism of plant growth-promoting action on cucumber(Jinyan No.4)were studied by measuring the secretion and cellulase activity of XJ-132 strain,as well as its resistance to plant pathogens and seed germination.The results showed that the degradation rate of rice straw was 58.00％after 35 days of liquid fermentation of XJ-132 strain,which could significantly promote the degradation of rice straw.By measuring the cellulase production ability of the strain,it was found that the hemicellulase and cellulase activi-ties of strain XJ-132 increased first and then decreased with the extension of culture time.The maximum activities of hemicellulase,endo-β-1,4-glucanase,exon-β-1,4-glucanase and β-glucosidase were 32.53,329.68,493.55 and 4.90 UmL-1,respectively.Bacterial infection experiments showed that XJ-132 strain had a certain inhibitory effect on soil-borne diseases,and had the best inhibitory effect on Fusarium wilt of banana,with a bacterium inhibition rate of 49.30％.The homology of 16s rDNA sequence analysis showed that XJ-132 strain had 99.93％homology with Bacillus subtilis.Further analysis was carried out that the secreted material composition of XJ-132 strain included the production of siderophore and indole-acetic acid,and had the ability to produce ammonia and HCN.In addition,the low concentration of XJ-132 strain fermen-tation broth had a promoting effect on seed germination,compared with CK,when the concentration of the bacterial liq-uid was 108 CFU·mL-1,the seed germination rate increased significantly by 4.66 percentage points.In conclusion,strain XJ-132 had high cellulase activity,which could not only rapidly degrade rice straw,but also had good antibacterial ability,and could promote seed germination.Through the isolation,screening and identification of straw-degrading bacteria,this paper provides a theoretical basis for the full utilization of straw resources in China.