Microbial Dynamic Changes During Garden Waste Composting In Substrate Production

This paper studied the dynamic change of microorganism in different types of gard-enwaste during the composting in the process of mass production process and its relationshipwith the material physicochemical property with the method of traditional separation combinedwith fluorescence quantitative PCR and DGGE combined with multivariate statistical analysis.Comprehensive survey the microbial biomass, diversity index and its physicochemical propertythat are the base of different garden waste. At the same time, screened the antagonistic microbeof phytopathogens to obtain functional matrix that can resist the pathogenic microorganism andprovide science and application foundation for making health cultivation matrix for the gardenwaste.The main research results are as follows：1. The composting process and physicochemical property analysis shows that thecomposting rate of grasses with lower lignin content is fast, the composting rate of brancheswith higher lignin content is relatively slow; the tempreture of the pile of grasses heat up fast,its high temperature can maintain longer than branches. These two garden wastes C/N ratioduring temperature rise period drop fast and then slow down in later stage; the pH and ECvalue of the compost body gradually increase, but the grasses EC value rise significantly higherthan that of the branches’. Meanwhile, the humification effect of these two compost materialsmainly occurs in the cooling and rotten stage of the composting. The effective phosphorus andpotassium content are with a small change ranges, the capacity shows a trend of gradualdecline. In addition, the compost initial C/N ratio of these two garden wastes is higher than thatof the general agricultural solid wastes such as straw.2. The counting result got from cultivable method to separate microorganism shows thatthe bacterial biomass of grasses compost pile, which temperature rises quickly and composttemperature is higher, are not lower than that of branches, the earlier stage is more higher. Thetwo kinds of compost body culturable microbial biomass in the whole change trend first rises then falls, with maturity stage rising slightly. The cultivable bacterial biomass is higher thanthat of fungal. The effect on culturable bacterial biomass with high temperature composting isless than that of fungal. Fluorescence quantitative test results show that the16S rDNA genecopy number in the bacteria of compost pile is far higher than that of fungi18S rDNA. Thecultivable counting and fluorescence quantitative analysis show that when the grasses composttemperature reaches the highest temperature, the microbial biomass significantly declines,while the branches conform to the rule of general material composting.3. DGGE research shows that the fungi diversity in both grasses and branches duringcomposting is lower than bacteria. The grasses bacterial diversity is lower than that of thebranches, but their fungal diversity have no big difference. The bacterial community duringcomposting changes a lot compared with fungi, so is the branches but with lower degree. Forthe bacteria and fungi group, the change of community of branches during composting isalleviated than that of grasses. Base on redundancy analysis method to analyse microbialcommunity composition, the sampling point and two-dimensional sequence diagram ofmicrobial population show that the great physicochemical impact factor on bacterialcommunity during grasses composting are pH value and total N content; The density andeffective P have great impact on fungal community. The density and humic acid have greatimpact on the bacterial community of the branches during compost, the temperature and total Ncontent have great impact on fungal community.4. The compost high temperature period (>50℃) of three kinds of garden waste (grasses,branches, and mushroom residue) are more than7d, which normally can kill or inhibit thecommon pathogenic bacteria in the compost body. The pH and EC value of the base material ofgrasses and branches are higher than that of mushroom residue. These three garden wasteshave higher initial nutrient after composting. The grasses has higher biological stabilitycompared with other two kinds of substrates. At the same time, preliminary screened andobtained4strains that can antagonistic of orchid black rot and5strains that can antagonisticbamboo root rot, which respectively are the main diseases of important landscape plants: orchid and bamboo. There are2bacterial strain have an antagonistic effect on those twopathogenic fungi. According to16S rDNA sequencing, the results showed that mostantagonistic strains belong to Bacillus.