Screening Of Bacterial Strains For Protein And Starch Biodegradation And Their Application Effects In Resources Recovery Of The Animal Manure

With the rapid development of large-scale aquaculture industry,a large number of animal manure will be produced every year.If these substances are not properly treated,they will cause serious environmental pollution and endanger human health.Poultry and livestock manure pollution has been juxtaposed with industrial wastewater and domestic wastewater,and has become one of the three major sources of water environmental pollution.At the same time,livestock manure is rich in nitrogen,phosphorus and potassium and other resources.How to realize its resource utilization has become a hot spot of animal husbandry research in recent years.Aiming at the specific problem that a large number of odorous substances will be produced in the process of resource treatment of poultry and livestock manure,effective strains of protein and starch degradation were isolated and screened from soil humus layer.On this basis,the strains selected were compounded to prepare compost fermentation agent,which was applied in liquid fermentation and solid composting experiments of poultry and livestock manure to prevent protein and starch from being degraded in the manure.The use of putrid bacteria produces a large number of odorous substances.The main results are as follows:1.Five strains of bacteria were isolated from soil humus layer samples by selective medium and identified by molecular biology as Lysinibacillus pakistanensis,Bacillus thuringiensis,Lysinibacillus boronitolerans,Bacillus acidicola and Bacillus licheniformis.2.Qualitative determination of bacterial protein degradation ability by gelatin liquefaction experiment showed that Lysinibacillus pakistanensis,Bacillus thuringiensis,Lysinibacillus boronitolerans and Bacillus licheniformis could rapidly degrade gelatin protein within 12 hours,forming a larger liquefaction hyaline circle,showing a strong ability to decompose protein.3.Amylase activity and starch degradation efficiency of five bacteria were quantitatively determined by starch fermentation medium.The results showed that amylase activity of Bacillus thuringiensis,Bacillus acidicola and Bacillus licheniformis was positively correlated with starch concentration in the range of0.5%-1.75%.Among the five bacteria,Bacillus licheniformis had the strongest ability to degrade starch.The degradability of starch reached 81.8%at 24h and 96.8%after 5days.4.The screened strains were mixed in a ratio of 1:1 to prepare fermentation agent and applied to liquid fermentation of pig manure.The results showed that the total organic carbon content decreased by 20.9%and total nitrogen content increased by 22.8%when inoculated with 1 g/100 mL compared with the blank control.Total phosphorus was retained.The total bacterial count was more than 1.0*10~9/mL,and fecal coliform count was significantly reduced.5.Compound microbial agents were further used in pig manure solid aerobic composting test and compared with commercial microbial agents.The results showed that the total organic carbon consumption increased by 38.4%and 12.8%respectively,the total nitrogen consumption decreased by 35%and 20%respectively,the total phosphorus content was similar,the content of fertilizer-effective substances was retained,and the total bacterial count was over 1.0*10~9/g,and the fecal coliform flora was effectively controlled.6.In the experiment of pig manure solid aerobic composting,the results of odor removal showed that after 18 days composting,the contents of indole,deodorant and ammonia decreased by 89.2%,78.8%and 94.4%respectively.Compared with the blank and commercial bacterial agents,the content of indole decreased by 36.5%and17.6%,the content of fecal odor decreased by 45.5%and 24.3%,and the content of ammonia decreased by 50%and 22.2%,respectively.The odor removal effect of inoculated compound bacterial agents was obvious.