Preparation Of Biochar-based Bacillus Subtilis SL-13 Formulations And Its Effect On Pepper Promoting Growth And Soil Improvement

Viable microbial organisms are most sensitive to changes in the environment and are vulnerable to adverse effects such as changes in temperature and humidity,soil composition and acidity and alkalinity,competition from soil-borne microorganisms,and predation by protozoa.As resulting in that the bacterial metabolism is unstable,the survival period is short,the number of effective live bacteria is low,and the application persistence is short during the production and application of the microbial formulations,this has led to the fact that the practical application of microbial preparations is also greatly limited.According to recent studies,biochar has rich carbon content,light weight,and porosity,which can effectively change bulk weight,structure,density,particle size distribution,increase cation exchange capacity and improve other physical and chemical properties of soil.In addition,biochar as a good soil conditioner can improve the maintenance of soil moisture and fertility.The biochar was prepared by high temperature pyrolysis at 400? and 600? from cotton straw and loaded with Bacillus subtilis SL-13.The influence of biochar on the growth of the bacteria was explored;we obtained the optimum conditions for biochar loaded Bacillus subtilis SL-13 through optimization of different conditions.We studied the release performance of bacteria from MBF and survival time of bacteria in biochar.Pot experiments were conducted to clarify the effect of Bacillus subtilis SL-13 of MBF on growth promotion of plants.The effect of MBF on soil improvement was determined by measuring soil physiochemical properties.The main research results are as follows:The addition of biochar to the liquid beef extract medium increased the propagation rate of Bacillus subtilis SL-13.Fourier-transform infrared spectroscopy(FTIR)showed that the adsorption of biochar on Bacillus subtilis SL-13 was not chemisorbed.The Scanning electron microscope(SEM)image shows that tubular structures are densely distributed in the biochar,and the average tube diameter is about 10?m.The bacteria can fully enter the tubular structures of biochar,the size of tubular meet the load conditions of the bacteria.As the size of biochar particles decreases,the adsorbed amount of bacteria adsorbed on biochar were increased.The survivals of B.subtilis SL-13 in biochar showed that the population of still maintained10~6 CFU/mL of biochar after 120 days.In addition,it is also concluded that MBF has a slow release effect on bacteria,and longer survival of bacteria in biochar.Therefore,biochar is a better carrier for Bacillus subtilis SL-13.Bacillus subtilis SL-13 of MBFs was obtained through the above optimal conditions,the effect on the growth of pepper and the physicochemical properties of soil were studied.Pot experiment results showed that the MBFs significantly increased the germination rate of the pepper(P<0.05),increased the dry weight,fresh weight,leaf number,leaf area,chlorophyll content and soluble sugar content of pepper.Moreover,MBFs promoted the development of pepper roots.It can be demonstrated that the Bacillus subtilis SL-13 of MBFs has a good promoting effect on pepper.MBFs reduce bulk density(BW),pH and electrical conductivity(EC)of soil,increase water holding capacity(WHC),organic matter content(OM)and soil cation exchange capacity(CEC)of soil,and slow the decrease of available nitrogen and available phosphorus in potted soil.Changes in the physical and chemical properties of the soil indicate that the microbial biochar preparation improves soil texture and makes the soil environment more conducive to plant growth.Therefore,MBFs not only have the effect of biochar to improve the soil,but also have improving the performance of PGPR.MBFs are environmentally friendly materials in agricultural applications for the promotion growth of plant and improvement soil environment.