Developmengt And Application Of Microbial Fertilizer Containing Polyglutamic Acid

Polyglutamic acid has the functions of water retention and slow-release fertilizer.It is widely used in agriculture.It can promote the germination of crop seeds,improve soil properties,and improve plant biomass and quality.The beneficial bacteria in microbial fertilizer can promote the absorption of nutrients in the soil,promote the growth of crops and improve the soil environment.However,due to the existence of some strains that can degrade polyglutamic acid,the application of polyglutamic acid in fertilizer is limited.Therefore,this paper first screened the non degrading microbial strains of polyglutamic acid,then screened the ability of phosphorus dissolving and nitrogen fixing of the strains,developed the microbial bacterial fertilizer containing polyglutamic acid,and studied the planting effect of bacterial fertilizer.The following research is carried out in this paper:（1）In this experiment,seven strains of Bacillus less degrading polyglutamic acid were screened,isolated and purified.Then seven strains were used as the starting strains to screen the microorganisms used in the compound microbial agent.After the screening,antagonism and bacteriostasis of inorganic phosphorus,organic phosphorus and nitrogen fixation,Bacillus licheniformis BYBC1.21057（Bacillus licheniformi）,Bacillus licheniformis BYBC1.20001（Bacillus licheniformi）,Bacillus megaterium BYBC1.20029（Bacillus megaterium）,Bacillus licheniformis BYBC1.21039（Bacillus licheniformi）,Bacillus licheniformis BYBC1.21041（Bacillus licheniformi）and other five strains were studied.（2）Single factor and response surface optimization experiments were used to optimize the fermentation medium and culture conditions of the selected strains:the box Behnken test design method was used to optimize the process parameters of microbial agent fermentation medium.The optimum growth conditions of microbial agent were glucose 10.00 g/L,soybean meal 13.71 g/L,ammonium chloride 2.29 g/L,yeast extract 9.00 g/L,potassium hydrogen phosphate 4.00 g/L Potassium dihydrogen phosphate 6.00 g/L and manganese sulfate 0.90 g/L.The initial p H was 6.0,the inoculation amount was 6%,the rotating speed was 300 r/min,the ventilation was 1:1vvm,the fermentation time was 28 h,and the effective viable number of microbial agents reached 2.5×10⁹CFU/ml,which is 363%higher than that before optimization.（3）The microbial fertilizer was prepared with the optimized microbial agent and polyglutamic acid fermentation broth（polyglutamic acid content 25 g/L）1:1,diluted 700times and used for the planting of Chinese cabbage.The single factor and orthogonal experiments of the formula conditions of the prepared microbial fertilizer were carried out.The optimum formula conditions of microbial fertilizer were p H 7.0,K₂SO₄concentration adjusted by potassium sulfate was 7%,Mg SO₄concentration adjusted by magnesium sulfate was 0.8%.After storage for one month,the effective number of viable bacteria was 5.34×10⁸CFU/ml,polyglutamic acid content is 23.26 g/L,the number of effective living bacteria is improved by 83.3%compared with the initial formula,and the content of polyglutamic acid is improved by15.8%compared with the initial formula,which meets the requirements of the number of effective living bacteria and polyglutamic acid content in the relevant standards of liquid microbial fertilizer.（4）Taking Chinese Cabbage（samolous parviflorus）as the experimental object,the application effect of microbial bacterial fertilizer was studied.The results showed that the combination of microbial bacterial agent and polyglutamic acid could significantly improve the root growth,plant height,fresh weight,dry weight and chlorophyll content of Chinese cabbage.Chinese cabbage grew better than the control group in the state of water shortage.Microbial bacterial fertilizer containing polyglutamic acid increased available phosphorus,alkali hydrolyzable nitrogen,nitrate nitrogen Total nitrogen content.