Studies On Screening Microorganism About Metabolism Of Carbon And Nitrogen And The Effect Of Adding Strains Back Into The Compost

Environmental protection and recycling utilization of resources are of the important topic of research.Composting is a way which can effectively convert organic solid waste into fertilizer then return to nature.However,as a traditional treatment,composting always takes a long period and low efficiency,it is necessary to add microbial cocktail to accelerate the metabolism of carbon and nitrogen in the compost to speed up the degradation of the material and composting maturity,and improve the quality of compost.Through enrichment and screening for many times,an effective cellulose degrader and a nitrifying bacteria were obtained from the cattle manure and stalks of cassava composting in the laboratory scale,through the morphological,physiological and biochemical identification and 16s rDNA sequence analysis,the cellulose degrader was preliminary identified as Nocardiopsis alba.,named CE5,and nitrifying bacterium as uncultured bacterium,named N7.Single factor method was used to optimized fermentation condition of strain CE5 and N7,the results showed that the optimal cultivation condition for strain CE5 was temperature of 30?,the initial pH of 9,inoculation amount of 4%,the speed of 180 r·min-1,fluid volume of 80 mL;strain N7 was temperature of 35?,the initial pH of 5?7,inoculation amount of 1%,the speed of 140 r·min-1,fluid volume of 120 mL.The strains were added to the compost materials in the early time,a control group named A and three experiment groups named B,C,D were set,which added CE5 in B,N7 to C,and mixed CE5 and N7 in D,respectively,and aerobic composting fermentation were started at the same time.The trends of fermentation temperature,pH,moisture content,organic matter and WSC,total nitrogen and the change of effective nitrogen content were investigated to study the effect of adding the strains on composting process.The results showed that adding strains had better performances than control group at each target.Compared with the control group A,group D was 4? higher at temperature during megathermal period,at the highest temperature,difference was 4.4?;pH changed more gently,weaker alkaline;at the end of composting,moisture content was 2.74%lower;organic matter degradation rate was 21.4%higher;total nitrogen was 13.4%higher;effective nitrogen content was 43.4%higher;the ratio of carbon to nitrogen between groups was similar,all got the standard of maturity.And combined with the observation of the physical properties of compost,scanning electron microscopy(SEM)analysis and biological toxicity test,adding strains had a better effect on maturity.PCR-DGGE analysis was used to study bacterial community in the composting process,and the result showed that groups of compost biological flora had the smilar trends in the composting process,but adding strains could reduce the diversity of compost microorganisms,make effective microorganism rapidly to become dominant bacterium,and promoted the compost into maturity.