The Effect Of Biogas Slurry On Bacillus Subtilis Spores And Preparation Of Preliminary Microbial Agent Forms

Bacillus subtilis is the most popular bio-control bacteria nowadays,it contains a variety of physiological characters,easy to be cultivated and could produce endospores,so it is considered as a better choice of bio-control bacteria.Biogas slurry,which is the residual liquid of methane fermentation,not only is rich in large amounts of easily absorbed nitrients,but also contains amino acids,a variety of trace elements,vitamins and other active material,which can be grown by microorganisms.With the continuous development of rural biogas project in China,much attention has been paid to the resource security processing and the utilization of biogas slurry.In this paper,Bacillus subtilis D1 has strong antagonism to rice seeding blight,which was found to grown in the cow dung biogas slurry.So,further optimized its ability to utilize the biogas slurry,which can provide a new metabolic pathway for the reuse of biogas slurry.Because it has strong antagonism to rice seeding blight,selecting excllent carrier and stable protectants to be preserved,as well as utilizing the biogas slurry inhigh efficiency.These also provide technical parameters for the later use of biological pesticides.In practical application,the content of spores is the key factor that influences the preparation of microbial agent.In this paper,adopting the batch culture method to optimize the spore culture medium of biogas slurry,the biomass and spore production were tested by using the turbidimetric method and the dilution plate coating method,the content of the metal in the biogas was analyzed by using flame atomic absorption spectroscopy,we firstly optimized the sporulation medium,then analyzed the carrier of inoculants type and protectant of microbial agent,which was aied at utilizing the biogas slurry in high efficiency,reducing the cost,increasing the spore production and preserving stablely,providing theoretical basis for its industrialization.The main results were as follows:?1?Activating the strain and measuring the growth curve.Bacillus subtilis D1 belongs to G+,it has strong antagonism to rice seeding blight,and at 19 h,it had the peak of growth.?2?Using single factor to confirm the best carbon and nitrogen sources were wheat bran and soybean powder.A set of optimal solutions of optimization test were obtained that the concentration of wheat bran was 2.45%,the concentration of soybean powder was 0.9%,the concentration of biogas slurry was 49.01%.At this time,the spore production was 87.82%.?3?Biogas slurry is contained in a variety of nutrients,and the biogas slurry contained N of1580 mg/Kg,P of 379 mg/Kg,K of 998 mg/Kg,its p H was 7.52 and the total solid content was 5.Biogas slurry can promote the Bacillus subtilis D1,because it contained of Ca²⁺,Mn²⁺ and Mg²⁺,we detected the content of these three kinds of ions in the biogas slurry,respectively Ca²⁺ was 14.8 mg/L,Mg²⁺ was 0.151 mg/L,Mn²⁺ was 0.08 mg/L.?4?The carrier of inoculants type and protective of microbial agent for the high-yielding strain were screened after optimizing the content of the culture medium,the best carrier is diatomite,the best protective agent is liquid paraffin oil.At last,the number of effective living bacteria could reach 89.9%.