Study On The Fermentation Of Biocontrol Fungus Agent Based On Coffee Grounds And Its Application In The Remediation Of Continuous Cropping Obstacles Soil

As the main waste of instant coffee production,coffee grounds have great resource utilization value because they are rich in crude protein,fiber and lipid.Continuous cropping obstacle is a serious problem in facility cultivation,and the development and utilization of bioremediation in soil obstacle is of great significance for the sustainable development of efficient agriculture in China.With coffee grounds as main ingredient,this study conducted three kinds of biocontrol fungus such as Trichoderma harzianum,Trichoderma viride and Beauveria bassiana for formula optimization research of solid fermentation,and modified test on the soil of continuous cropping obstacles was carried out by using the combination of the above three kinds of fungus,which was used to analyze the effects of the straw with biocontrol fungus agent combination on the physicochemical property,bacterial community structure,abundance of nitrogen metabolism genes and beneficial fungi of continuous cropping obstacle soil.(1)According to the conventional solid fermentation formula of wheat bran,fermentation experiment was carried out by using coffee grounds to replace wheat bran with different proportion,and determined the spores content of fermentation products.The results showed that compared with the traditional wheat bran fermentation formula,the optimized formula with coffee ground as the main material could significantly increase the spores content of the fermented products,and the spores content of fermentation products of Trichoderma harzianum,Trichoderma viride and Beauveria bassiana increased respectively by 35.1%,110.9%and 68.5%.(2)Studies were carried out to figure out the effects of straw+compound biocontrol fungus agent,straw+straw rapid decay agent and pure straw on the physicochemical properties of soil with three different salts content.Results showed that the application of straw+compound biocontrol fungus agent could reduce nitrate nitrogen content of medium and high salinity soil effectively after 92 days,which mean that using 20 g straw,4 g Trichoderma harzianum agent,2 g Trichoderma viride agent and 2 g Beauveria bassiana agent per kg soil could reduce 282.70～361.91mg nitrate nitrogen,and significantly increased the content of organic matter,available phosphorus and ammonium nitrogen,and reduced the salt content,and improved seedling emergence and yield of green vegetables.Meanwhile,the effects of straw+compound biocontrol fungus agent was also more obvious than straw+straw rapid decay agent and pure straw(3)The abundance of trichoderma and nitrogen metabolism genes such as norB,AOB was quantitatively analyzed by real-time quantitative PCR.Results showed that the straw+compound biocontrol fungus agent could reduce the relative abundance of the norB and the AOB genes of the medium and high salinity soil,but the effects of that was no significant difference with straw+straw rapid decay agent and pure straw,while other indexs including the relative abundance of trichoderma,the abundance and the abundance ratio of bacteria and fungi could also be significantly increased which were obviously higher than other two recipes’ indexs,but the effects on high salinity soil was more remarkable than medium salinity soil.(4)High-throughput sequencing analysis of soil bacteria in different treatments was carried out based on Illumina Miseq platform.The results showed that the bacterial community structure in the soil treated with straw+compound biocontrol fungus agent changed significantly compared with the control group,and it has obvious difference between the treatment with straw and straw+straw rapid decay agent,and it also promoted the convergence of the bacterial community structure in the medium and high salinity soil Through correlation analysis,it was found that the increase of organic matter and ammonium nitrogen content and the decrease of nitrate nitrogen content were the main environmental factors driving the improvement of soil bacterial richness and diversity in continuous cropping barrier soil treated with straw+compound biocontrol fungus agent.Using FAPROTAX on bacterial community structure function prediction showed that the relative abundance of heterotrophic bacteria and hydrocarbon degradation functional groups in continuous cropping barrier soil could be significantly increased by applying straw+compound fungus agent,and the relative abundance of photoautotrophic bacteria,aromatic compounds degradation functional groups,nitrification and nitrate reduction functional groups could be significantly reduced compared with the control group.At the same time,compared with straw+straw rapid decay agent and straw,straw+compound biocontrol fungus agent has more obvious effects on medium salinity soil than high salinity soilUsing coffee grounds to ferment biocontrol fungus can increase the yield and quality of productions significantly.Applying straw+compound biocontrol fungus agent can significantly improve the physicochemical properties and microbial community structure of the soil with continuous cropping obstacles,and its effect is better than straw + straw rapid decay agent and straw.