Screening Of Bacillus Strains Function For Fermentation Bed Application

With the rapid development of livestock and poultry breeding, pollution caused by animal dung has become a serious problem that can not be ignored and night soil innocuous treatment is the inevitable trend of development. With green agriculture becoming the direction of agricultural development in the world today, Strongly advocating the use of microorganisms and taking the road to sustainable development are the inevitable trend and choice of agricultural development in our country. New culture technology with microbial fermentation can effectively solve the problem of excreta disposal and environmental pollution in swine production, which is superior to traditional intensive, large-scale pig-raising, with high social and economic benefits.35 strains of bacteria which can produce spores were isolated from the soil of pig farms and sewage by heating enrichment and serial dilution plating. The Strain named Z-22 with high ability of deodorization, with a removal rate of ammonia at 29.2% and hydrogen sulfide at 52% was identified. G-4 with a high removal rate of ammonia nitrogen and macromolecular material was also isolated with a removal rate of ammonia nitrogen at up to 70%. With the analysis of colony morphology, physiological and biochemical propertres, and 16S rDNA gene sequence, strain Z-22 was finally identified as Bacillus amyloliquefaciens, strain G-4 was identified as Bacillus velezensis.Spore is the best form of microbial agents, which has strong tolerance for bad environments. In order to improve the spore production rate and spore quantity of strain G-4 and Z-22, single factor experiment and orthogonal experiment in conditions of spore formation were studied. The results showed that the best conditions of spores formation for strain Z-22 were 0.5% corn flour, 2% soybean meal, 0.3% FeSO₄·5H₂O, 0.05% MgSO₄·7H₂O, initial pH 7.5, culture time 20 h, and bottle filling capacity 30 mL/250 mL, fermentation time 48 h. Under this optimum condition, the spore quantity of strain Z-22 achieved 2.1×109 cfu/mL and the spore production rate achieved 97.16%. The best condition for spores formation of strain G-4 was as follows: 0.5% corn flour, 2% soybean meal, 0.3% MnSO₄·H₂O, 0.05% MgSO₄·7H₂O, initial pH 7.5, culture time 18 h, and bottle filling capacity 50 mL/250 mL, fermentation time 48 h. Under this optimum condition, the spore quantity of strain G-4 achieved 1.9×109 cfu/mL and the spore production rate achieved 94%. The optimization, which reduced the fermentation time and increased the spore formation, provide the foundation for industrial production.Different proportions of G-4, Z-22, N-8 were combined to form a complex bacteral mixture. The mixture’s capacity in ammonia usage, removing odor and degradation of macromolecules were evaluated and the best combination was found to be as follows: G-4 seed solution （3% inoculum size）, Z-22 seed solution （3% inoculum size） and N-8 seed solution （3% inoculum size）. The removal rate of the complex bacterial mixture of ammonia was 33.78% and hydrogen sulfide was 56.64%, the complex bacteria mixture is superior to monoclonal strain in removing odor. the removal rate of the strain of ammonia nitrogen was up to 70%, which provided germplasm resources for the production of microecology fermentation bed farming and manure compost.