Antifungal Spectrum Of Bacteria A178from Rhizosphere Soil And Preliminary Study Of Its Formulations

A178is a strain of Bacillus subtilis, isolated from the plant rhizosphere soil. Former research has shown that the A178strain has the stronger antifungal ability to cotton verticillium wilt fungus. In order to further make clear the bio-control effect of the strain and its prospects for application, the strain of antifungal spectrum was verified during experiments, and formulations were developed and the related effect factor was analyzed.A178strain cultivation conditions were further optimized, the optimal incubation time was24h, the optimal liquid volume was40ml/250ml, the optimal inoculation ratio was2%. A178strain, which was cultured in the optimized culture conditions, showed the stronger inhibiting of the growth of the18pathogen isolates, from5genera respectively, such as Colletotrichum.Fusarium, Corynespora, Botrytis and Altrnaria. A178strain showed the strongest antifungal ability to C7-2strain (Colletotrichum gloeosporioides Penz) from wenchang in all pathogen strains, and its anfungal ratio was71.93%. The mango anthrax C7-2strains was verified as the main targets in follow-up experiments. After A178strain was sprayed on the inoculated mango leaves with C7-2strain, the mango anthracnose spot size in the leaves was2.01cm2in5d,39.34%smaller than in the control group; After treating mango leaf tissues with A178, it made the production rate of reactive oxygen species super oxygen anion and the content of hydrogen peroxide in mango leaf tissues increase more than in the control group; A178strain can enhance the expression of defense genes, such as CHT, PPO, PAL, PR and PDF to different degrees in mango leave tissue, and enhance plants resistance to disease.For A178and HAB-5(Brevibacillus brevis) and HAB-1(Bacillus atrophaeus) bio-control strains, by optimizing the conditions of cultivation, suspension concentrate agent (SC) and capsule suspension (CS) were respectively made.With mango anthrax fung(Colletotrichum gloeosporioides Penz.) C7-2strain as the target, the two formulations were tested for further verifying the A178strains antagonistic ability. The results of the experient showed three kinds of glue bio-control bacteria SC, only A178SC in10times and800times dilution antifungal effect is better than the original strain, others are weaker than the original strain. HAB-1SC even lost it’s antifungal ability; among the three kinds of bio-control bacteria CS, A178under the100.400,800times dilution degrees, its antifungal effect is better than the original strain, the improved antifungal ability were0.49%,0.29%and3.04%respectively, the antifungal effect of HAB-5in dilutions of different degrees were higher than the original strain, respectively increased by 5%,3.3%,5.11%,2.22%,1.74%and4.25%. But the HAB-1CS formulations antifungal effect was weakened compaced to(or over) its original strain. It showed microcapsule formulations can enhance HAB-5and A178strains inhibiting the ability of pathogenic fungi. And HAB-5CS formulation under diluted400,800and1000times, were able to enhance the growth of tomato seeds more than the corresponding bacteria liquid under the same concentration, the germination tendency also increased by11.2%,5.6%and11.2%, respectively, germination rates increased by8.7%,4.4%and13%respectively; Radicle increased by2.8%,25.7%and48.6%, respectively; germination rate increased by33.9%,133.9%and-18.6%, respectively.Every ingredient in SC added to the LB medium for incubating the A178strain, the SiO2can improve the A178strains antifungal rate, the rate of improve was0.553%, other ingredients decreased the A178strain abtifungal ability, the reduced range was between3.22%—5.074%. The CS component joined the LB to cultivate A178strain, however the anfungal ability of A178strain was weakened, Span-80reduces A178antifungal rate by0.074%against C7-2strain. With soybean oil, the antifungal rate reduced by2.11%, with maltodextrin, the antifungal rate dropped by7.11%. The most effective is chitosan which inhibited the A178antifungal ability, making the A178strain lose its anfungal ability against mango anthrax. The impact of each component of SC on HAB-5for different. Organosilicone for HAB-5fungistatic capacity decreased by a rate of0.11%. Sodium lignosulphonate impact on HAB-5fungistatic rate had almost no effect. Ethylene glycol and sodium benzoate effect on the fungistatic rate of HAB-5was slight improvement of1.37%and2.04%. Effects of castor oil on the HAB-5fungistatic capacity was slightly greater,its fungistatic rate increased by4.68%. The effect of SiO2and xanthan gum for HAB-5fungistatic capacity was the largest; fungistatic rate increased by9.33%and8.52%, respectively. CS composition of chitosan on the growth of HAB-5and antifungial ability has a fungistatic effect,Its fungiostasis ability have no been completely reflected; Twain, span-80and xanthan gum for HAB-5fungistatic ability enhancement effect are the most obvious, fungistatic rate increased by7.04%,6.48%and8.52%;Maltodextrin and silicaenhance on the role of HAB-5fungistatic capacity gave a slightly reduced increase of5.07%and3.52%. Soybean had the smallest improvement in the role of HAB-5antifungial capacity of the weakest.fungistatic rate only increased0.55%. When the SC component is joined to the NB medium to develop HAB-1strain, SiO2and castor oil were found to enhance the HAB-1antagonist ability. The increased antifungal rates were0.37%and2.03%respectively, lignin, ethylene glycol, xanthan gum, and organic silicon made HAB-1strain antagonist ability slightly lower, the antifungal rate were reduced by0.15%.0.19%, 1.93%and0.12%respectively. Sodium benzoate made HAB-1lose its antifungal ability to mango anthrax fungi. It suggests that Sodium benzoate was one of the important factors of SC formulation of HAB-1strain losing it’s antifungal ability to the pathogen.