Isolation And Identification Of Bacterial Strains And Their Application In Deep-litter System

Along with the development of livestock and poultry industry in China, the livestock and poultry manure pollution is becoming more and more serious, and the deep-litter system was introduced and applied. It is important to screen deodorizing bacteria and use in the local deep-litter system that can build a healthy livestock breeding system, and improve the quality and yield of animal products.In this experiment,105 bacterial strains were isolated and purified, and seven strains which don not produce NH3 and H2S were screened. The original growth pH range, growth temperature, utilization of carbon and nitrogen sources, protease activity and amylase activity, toxicity test was done; furthermore, the genetic aspects of the strains were analyzed.Base on the results, one deep-litter system was built, and the ferment time was 15d. During the course of fermentation, we detected variation of the temperature, pH value, ammonium and nitrate content, and the number of bacteria, fungi and actinomycetes. Finally, PCR-DGGE technique was used to reveal the microbial dynamics during the fermentation process. The results were as the follows:1. Seven bacteria screened belong to gram-positive, can grow at high temperature, but can't grow at low temperature. These strains couldn't grow at 4℃and 10℃, however, they grew well at 45℃, and four of those can even grow at 60℃. These strains can also grow at original pH 8.0 to pH 10.0, but couldn't grow at original pH 4.0, which showed that these strains had low tolerant to acid environment.2. Analysis of physiological and biochemical tests showed that, all the strains could digest starch, and used mannitol, glucose as sole carbon sources. These strains could use most tested ammonium acid, and NH4+-N, NO2-N as sole nitrogen source.3. BOXAIR-PCR revealed that the genetic differentiation was existed, and 16S rDNA PCR-RFLP divided these strains into 5 genotypes,16S rDNA sequences of 3 representatives showed that, stain B1, B5 and B7 belonged to Bacillus stubtlis, Bacillus badius, and Bacillus licheniformis.4. The results of mouse toxicity tests showed that mouse feed with strain B5 grew well, and there was no dead mouse, anatomic observation showed that no organic lesion was observed, which suggested that the tested strain had no pathogenicity to the trial mouse.5. During the fermentation process, after inoculation of bacterial strain B5, the temperature in the fermenting bed increased to 45℃rapidly within 24h, and the highest was 70℃, when fermentation process completed, the temperature in the fermenting bed remained 50℃. At the same time, the content of ammonium nitrogen and nitrate nitrogen decreased quickly, and changed from 108.6mg/kg and 138.72 mg/kg at beginning to 44.6 mg/kg and 52.32 mg/kg on the 8th days, and then increased a little.6. PCR-DGGE analysis showed that the bacterial communities in the litter material in the course of fermentation had little changes, and was stable.