Effects of antibiotic on nitrogen transformation during substrate fermentation and edible fungi cultivation
[Objective]This study explored the effects of antibiotics(monensin)on nitrogen conversion and comprehensive utilization efficiency of agricultural waste in the process of crop straw feeding-substrate fermentation-edible fungus cultivation to provide basis for comprehensive utilization system of planting and breeding and utilization of agricultural waste.[Method]Thirty beef cattle from a farm in Liaoyuan,Jilin were randomly divided into two groups and fed for 60 days.Feed of one group was added with antibiotic monensin(RA),while the other group was not added(RN).Beef cattle manure was collected and mixed with rice straw for fermentation for 35 days.Emissions of NH3 and N2O were measured during the fermen-tation process.During fermentation and cultivation,total nitrogen content of the substrate was also deter-mined.The effects of antibiotics on nitrogen transfer and nitrogen recovery during substrate fermentation and Agaricus bisporus cultivation were investigated by measuring yield and total nitrogen content of A.bisporus fruiting body.Water content,temperature,C/N,pH,urease,nitrate reductase and nitrite reductase activities of the substrate during fermentation and A.bisporus cultivation were measured.The 16S rRNA and ITS sequencing were used to characterize bacterial and fungal population composition in the fermenta-tion substrate.[Result]In the fermentation stage,residual antibiotics in the substrate did not change the trends of substrate temperature,water content and C/N,but average temperature in the high temperature period decreased by 1.1 ℃ and emissions of NH3 and N2O decreased.More nitrogen remained in the sub-strate(nitrogen retention rate of RN and RA treatments were 39.58％and 43.23％,respectively)and anti-biotics inhibited nitrogen transfer.Compared with RN treatment,physical and chemical properties of the substrate after RA treatment were not conducive to the growth of A.bisporus mycelium.The initial activi-ties of urease,nitrate reductase and nitrite reductase in RA treatment were higher than those in RN treat-ment(P＜0.05).After the start of fermentation,the activities of urease and nitrate reductase in RA treat-ment were lower than those in RN treatment,and the activity of nitrite reductase was still higher than that in RN treatment.After the end of cultivation,the urease activity of RA treatment exceeded that of RN treatment,and the activities of nitrate reductase and nitrite reductase were still lower than those of RN treatment.In the cultivation stage of A.bisporus,residual antibiotics in the substrate affected the growth of A.bisporus mycelium,increased water content and pH of the substrate,decreased the C/N of the sub-strate before the beginning of fruiting,and finally decreased the yield of A.bisporus.The nitrogen recovery rate decreased from 0.17％(RN)to 0.11％(RA).After the fermentation process,the relative abundance of phyla Proteobacteria and Bacteroidota and that of genus Marinobacter and Mycothermus was decreased,while that of phyla Firmicutes and Actinobacteriota and genus Pseudoarmillariella was increased.[Con-clusion]Residual antibiotics in the substrate inhibited the transformation of nitrogen and more nitrogen re-mained in the substrate,which affected the growth of A.bisporus and reduced nitrogen conversion.
万方数据
维普
