Effects Of Microbial Enhancement On Mixed Aerobic Compost Of Rice Straw And Vegetable Waste

With the rapid growth of population in China,the consumption of grain and vegetables is increasing year by year,and the pollution problem of crop straw and vegetable waste is becoming more and more serious,restricted the development of agriculture.In this study,rice straw and vegetable waste were used as raw materials for composting,and the lignocellulosic fast-decomposing consortium was used as an inoculant to investigate the effect of microbial enhancement on composting process and microbial diversity.The raw material for composting was rice straw and vegetable waste,and the fermentation was mixed at a mass ratio of 7:3.Microbial enhancement was carried out by inoculating the raw material with 5%(V/V)of a lignocellulosic fast-decomposing consortium,and the initial volume of the composted material was 1.52 m~3.The experiment lasted 42 d.Physicochemical and biological indicators of the composting process were sampled and measured at different periods during the composting process.The results showed that the high temperature period(≥50°C)of the pile in the test group was maintained for 21 d,with a maximum temperature of70.2°C;the high temperature period of the control was maintained for a total of 15 d,with a maximum temperature of 65.6°C.By the end of the composting test,the p H of the material in the test group was 8.5,the organic matter content of the decomposed material was 37.55%,the contents of TN and TK were 1.39%and 2.15%,respectively,the C/N was 15.79,the seed germination index was 81.2%,and the degradation rates of cellulose,hemicellulose and lignin were 16.66%,3.22%and 5.62%,respectively;the composted material in the control group The p H of the control compost material was 8.3,the organic matter content of the decomposed material was 44.34%,the contents of TN and TK were 1.31%and 1.99%,respectively,the C/N was 17.03,the seed germination index was 73.2%,and the degradation rates of cellulose,hemicellulose and lignin were 11.42%,2.29%and 4.37%,respectively.The results of microbial diversity changes in the composting process by high-throughput sequencing technology showed that at the bacterial phylum level,the main dominant bacterial phylum compositions of the test and control groups were the same,mainly derived from eight bacterial phyla including Proteobacteria,Firmicutes and Actinobacteria.The composition of the main dominant bacterial genera in the test and control groups was significantly different.The dominant genera in the test group were mainly from eight dominant bacterial genera,including Pseudomonas,Comamonas,Gemmatirosa,Cellvibrio and Fibrobacter.The dominant bacterial genera in the control group were derived from 11 bacterial genera including Pseudomonas,Cellvibrio,Acinetobacter,Pseudoxanthomonas,Thermobifida and Thermopolyspora.Among the fungal taxa,the dominant phyla in both the test and control groups were Ascomycota and Basidiomycota.At the level of fungal genera,Wallemia,Mycothermus and Aspergillus were the dominant genera in the test group.Mycothermus,Iodophanus,Coprinus,and Aspergillus were the dominant genera in the control group.The rice straw and vegetable waste were composted for 42 d.The material maturity well.Compared with the control group,the test group had higher temperature,longer duration of high temperature period,better effect on lignocellulosic material and higher nutrient content of the maturity.In terms of bacterial taxa,the diversity and abundance of dominant microorganisms in the high temperature and cooling periods were significantly higher in the test group than control group(p<0.05).In terms of fungal taxa,the diversity of dominant microorganisms in the middle and late stage of compost was significantly higher in the experimental group than in the control group,but the diversity of fungus in the raw materials of the control group was significantly higher than in the test group(p<0.05).The expression of genes related to cellulose degradation was found to be significantly higher than those related to hemicellulose and lignin degradation in the macrogenome annotation results of compost samples from the test group.In conclusion,microbial fortification can promote the rapid start-up of compost,prolong the duration of the high temperature period,significantly increase the nutrient content of the decomposed material,and make the material fully decomposed to meet the requirements of harmlessness.It also significantly increased the diversity and abundance of bacteria and fungus,and had inhibitory and killing effects on harmful fungus.