Studv On The Variability Of Microbial Flora During SMS Vermicomposting And The Effects Of Vermicompost On Plant Growth And Induced Disease Resistance

In China,about 150 million kilograms of spent mushroom substrate(SMS)are produced every year.The storage and treatment of the SMS have resulted enormous economic and environmental problems.Developing new technology of rational utilization of SMS is an effective way to solve this problem.Vermicomposting is a low cost,high efficiency and significant benefit technology for organic waste fertilization.This study focused on the treatment and utilization of Pleurotus eryngii residue by vermicomposting.Firstly,suitable composting conditions were screened.Secondly,the chemical composition and variability of microbial flora during vermicomposting were analyzed.Finally,the effects of vermicompost on tomato growth and root-knot nematode control were tested.The main results were summarized as the follows:1.By using SMS,macadamia nut shell and lignite respectively combined with cow dung as substrates,and taking the earthworm biomass as indicator,the suitable matrix formulation for vermicomposting was screened,and the changes of main chemical components in the matrix before and after vermicomposting were analyzed.The results showed that SMS mixed with cow dung in different proportions was the most suitable substrate for vermicomposting.Of which,the earthworms increased their biomass maximally(24.39 g),followed by the the treatment of macadamia nut shell(13.41 g)and lignite(9.98 g)when mixed with cow dung,respectively.For the treatments of SMS mixed with cow dung,during pH values of the substrate decreased from 8.59 to 7.12.Of which,pH of T2(SMS:cow manure = 8:2)decreased mostly(1.47).The humic acid,total nitrogen,total phosphorus and total potassium in all treatments increased variously.OF them,the contents of humic acid and total nitrogen in TO treatment(pure SMS)respectively increased by 12.77%and 0.75%,the total phosphorus content increased by 0.23%in T1 treatment(SMS:cow dung = 9:1),and the total potassium content increased by 0.61%in T3 treatment(SMS:cow dung = 7:3).2.High-throughput sequencing technique was used to analyze the microflora variability of SMS during the first three weeks of vermicomposting.The results showed that the alpha diversity index of all treatments showed an upward trend,by beta diversity analysis showed that vermicomposting made the differences between treatments smaller.For bacteria in the phylum level,the abundance of Bacteroidetes,Fibrobacteria and Actinobacteria increased,while the abundance of Proteobacteria and Firmicutes decreased.Planctomycetes and Acidobacteria fluctuated during vermicomposting.In genus level,the abundance of Cytophaga and Pseudoxanthomonas increased,while that of Sphingobacterium and Massilia decreased.For fungi,Ascomycota was the dominant phylum,followed by Basidiomycota and Ciliophora.There was no regular variability in the phylum level of all treatments.In the four treatments,there were some genera whose abundance increased,such as Chaetomium,Mucor,Rhizopus,but none of the genus with abundance decrease was found in all the treatments.3.Pot experiments were conducted to determine the effects of vermicompost on tomato growth and root-knot nematode control.Additionally,the activities of three defense enzymes(PAL,POD and CAT)related to plant disease resistance were analyzed during the period of plant growth.Comparing with the control(pure soil),soil mixed earthworm manure could significantly promoted tomato growth and suppressed root-knot nematode.Of the G33(SMS:cow dung = 7:3,75%added to soil)treatment,the tomato height increased 142.44%,the fresh weight of the aboveground part increased 338.71%,the root length increased 122.18%,and the nodule number caused by root-knot nematodes decreased 83.02%.Comparing with the control,the activities of three defense enzymes were increased,and there was a positive correlation between the activities and the amount of vermicompost added in the soil,which indicated that vermicompost could increase the defense enzyme activities which possibly enhanced the resistance of tomato aganist root-knot nematode infection.4.Sn-9-2,a bacterium from cave soil was identified as a new species using method of polyphasic taxonomy,and named as Aquabacter cavernae.