Changes Of Dominant Microbiota During Cattle Manure Composting And Preparation Of A Microbial Inoculant For Composting

With the rapid development of livestock and poultry raising industry, the increased amount of animal manure has been causing significantenvironmental concerns. To solve this problem, composting has been considered an important method for manure wastes disposal. However, in traditional composing process, the small amount of microbes in manure compost limited the efficiency of manure fermentation and increased the time consumed for compost maturity. In the present study, molecular biology techniques such as PCR-DGGE were applied to develop the mixed microbial inoculant for increasing the efficiency and saving the time for cattle manure composting.To evaluate the impacts of microbial inoculant on cattle manure compost, the mixed microbial inoculantwas prepared and inoculated into cattle manure for composting in this study. The main findings are listed as follows:1. With established fresh cattle manure compost and detected physical and chemical indicators, the results indicated that the time for temperature rising over55℃was6days with the highest temperature reached to61.3℃. The moisture content ofcattle manure decreased from63.74%at the beginning of composting to46.65%at the end of composting.And the compost showed a weakly alkaline range of pH value from8.0to9.0. Moreover, the ratio of C/N showed a decreased trend during composting. With comprehensive analysis of the four indicators, the results showed that the cattle manure compost we established conformed to the compost general trends, and the composting specimens in mild thermal and hyper thermal stage during composting could be used to screen microbes in cattle manure.2. Microbes were cultured with ordinary culture medium, and16S rDNA of microbes were amplified, sequenced and aligned.Twenty-seven microbes were screened in total, among which,2microbes belong to Pseudomonas,15microbes belong to Bacillus,2microbes belong to Cellulomonas,2microbes belong to Streptomyces,4microbes belong to Thermoactinomyces,1microbe belongs to Nocardia, and1microbe belongs to Miromonospora. With PCR-DGGE,2microbes belong to Cellulomonas,8microbes belong to Bacillus,1microbe belongs to Streptomyces and1microbe belongs toThermomosporawere determined as the dominant microbes in mild thermal and hyper thermal stage during composting. 3. With equal amount of12microbes, the mixed microbial inoculants was preparedand inoculated into manure compost with a final ratio of0.73%. Compared with control group, the time consumed for temperature raising to55℃was one day less with microbial inoculant, and the highest temperature was64.7℃. Also, the inoculation of mixed bacterial inoculant increased germination index (GI) to86%on day22, while the GI in control group was only73%on the same time point, which indicated the effectiveness of mixed bacterial inoculant on promoting compost maturity with faster degradation of toxic components in manure for plants. Furthermore, with mixed bacterial inoculant, compostalso showed a shorter time (one day less) for inactivating E.coli in cattle manure.In summary, the mixed bacterial inoculant promoted the temperature rise in cattle composting, accelerated the degradation of organic materials and compost maturity, with shorten time for composing, the inoculant prepared in this study facilitates the harmless disposal and resources utilizations of livestock and poultry manure.