Screening Of Multifunctional Bacillus Of Biological Fertilizer And The Study Of Its Mechanism

Bacillus was an ideal strains of biological fertilizer, had the advantages of strong resistance, simple nutrition, fast breeding, high available bacteria count, stable performance, long shelf life and become a research hotspot in recent years. In addition, most of the bacillus strains were born with disease prevention, growth promotion, phosphate and potassium solubilizing, and nitrogen fixation, and had important practical significance to developing ecological agriculture.This research used the method of flat confrontation, antagonistic activity determination of fermentation filtrate, potted plant growth test, and soil nutrient and soil microbial groups analysis to screen functional bacillus strains.Two bacillus strainsB06andB07were founded with broad-spectrum antagonistic activity against plant pathogen fungi.B06was more effective in inhibiting8pathogenic fungi than other strains, with R2/R1ranging from0.4to1.8, and the inhibition rates of sterile fermentation filtrate from66.7%to87.5%.B07took second place in inhibiting8pathogenic fungi than other strains, with R2/R1ranging from0.23to1.21, and the inhibition rates of sterile fermentation filtrate from55.56%to81.25%. And Five bacillus strains B03～B07were founded with promoting growth to cabbage. Among them,B04was more efficient in promoting plant growth than other strains, and compared to the control, the total dry weights of plant were increased by12.8%and14.5%. Seven bacillus strains B01、 B09and B03～B07were founded with activating nutrient, but onlyB06had the ability of activating nitrogen both in30days and60days, and the activation rate was19.5%.The moprhology, Physiological and biochemical characters ofB04、B06andB07were studied, which indicated thatB04was Bacillus tequilensis, the sequence identity was99.914%with Bacillus tequilensis10bT(HQ223107),B06was Bacillus amyloliquefaciens subsp. Plantarum, the sequence identity was99.862%with Bacillus amyloliquefaciens subsp. plantarum FZB42T(CP000560),B07was Bacillus amyloliquefaciens subsp. amyloliquefa-ciens, the sequence identity was99.793%with Bacillus amyloliquefaciens subsp. amylolique-faciens DSM7T(FN597644).The research of mechanism indicated that bacillus strainsB06andB07were not producing chitinase, its mechanism of antagonistic activity against plant pathogen fungi were by producing some metabolic substances, to make the pathogenic fungal hyphae cell distortion, vesicle, stigmas shrinking dry mycelial extracellular wall, so as to achieved bacteriostatic action.B04andB06gradient dilution had obviously improved melon seed germination rate, promoted the growth of radicle and hypocotyl.Compare to control treatment, germination rate of melon seed increased by7.41%to93.3%under the treatment of different dilution gradient ofB04metabolic liquid. Hypocotyls and radicle length of melon seeds increased by9.7%to9.7%and16.9%to32.2%,15.63%to59.9%and4.9%to26.8%, under the treatment of different dilution gradient ofB04andB06metabolic liquid. Results of soil nutrient determination indicated that all bacillus strain were efficient to decomposite organic matter. Bacillus strainsB06could release nitrogen, phosphate and potassium. B03、B04、B05andB07could release phosphate and potassium.Adopting L16(45) orthogonal test, choice the factor temperature, pH, speed, inoculation quantity and liquid quantity to optimize the liquid fermentation condition of bacillus strainB04,B06and B07. The optimal fermentation conditions ofB04was emperature30℃, pH7.0, speed180rpm/min, inoculation quantity7%and liquid quantity25%, available bacterium was3.15×1011cfu/mL, and spore rate was82%, increased by7.9%than before optimization. The optimal fermentation conditions ofB06was emperature30℃, pH7.5, speed220rpm/min, inoculation quantity3%and liquid quantity15%, available bacterium was2.1×1013cfu/mL, and spore rate was85%, increased by6.3%than before optimization.The optimal fermentation conditions ofB07was emperature30℃, pH7.0, speed220rpm/min, inoculation quantity7%and liquid quantity25%, available bacterium was3.3×1013cfu/mL, and spore rate was92%, increased by12.2%than before optimization.Field test indicated that bacillus strainsB04andB06were more efficient to promote plant growth. Potato output increased by3.4%and15.3%respectively underB04andB06bacteria agent treatment. BesidesB06could not improve potato POD enzyme activity, bacillus strain B06, B07,B06-B07andB04-B06-B07can improve melon leaf and potato leaf PPO and POD enzyme activity. Compare to control treatment PPO and POD enzyme activity of melon leaf increased by32.9%and74.3%, under the treatment of B06-B07treatment. PPO and POD enzyme activity of potato leaf increased by6.1%and12.3%, under the treatment ofB04-B06-B07treatment.