| Previous laboratory studies have shown that Bacillus megaterium L2 has a strong broad-spectrum antibacterial activity against a variety of pathogenic bacteria and fungi through plate confrontation and other experimental methods,and a variety of antibacterial activities were isolated and identified from Bacillus megaterium L2 by biological activity tracking method.Monomer compounds,and the antibacterial mechanism of the compounds was explored.In this paper,the number of viable bacteria was used as the response index,and the optimal medium composition and fermentation culture conditions of L2 were obtained through single factor experiment and response surface optimization.Biocontrol effects against tea anthracnose and tea cake disease.The main results are as follows:1.Determine the optimal fermentation conditions.Taking the number of viable bacteria in the fermentation broth of strain L2 as the response index,the optimal fermentation process of Bacillus megaterium L2 was obtained through single factor experiment,Plackett-Burman test,steepest climbing test and response surface optimization experiment.That is,the medium uses lactose as carbon source,lactose concentration 10 g/L,yeast powder as nitrogen source,yeast powder concentration 11g/L,Na Cl addition 10 g/L,inoculum volume 6%,medium p H 6.5,shaking When the bed speed was 175 r/min and the culture temperature was 30℃as the optimal fermentation conditions,the number of viable bacteria of Bacillus megaterium was the highest,and the number of viable bacteria was 7.11*10~9CFU/m L.It is 2.4 times higher than that before optimization(2.1×10~9CFU/m L).2.Obtain L2 wettable powder.Taking the wettability,suspension rate and fineness of L2 WP as the response indicators,through the screening experiment of carrier,auxiliary,auxiliary ratio,auxiliary dosage and protective agent,the optimal formula of L2 WP was obtained.When the carrier of Bacillus megaterium L2wettable powder is white carbon black,the dispersing agent is sodium lignosulfonate,the wetting agent is sodium dodecyl benzene sulfonate,the compounding adjuvant ratio is 4:6,and the compounding adjuvant is When the dosage of L2 WP is 8%,and the protective agent is hydroxymethyl cellulose,the quality of L2 WP product is the best.The product has a bacterial rate of 0.7%,p H of 7.1,fineness of 99.16%,wetting time of 93 s,suspension rate of 92%,water content of 1%and a bacterial count of5.25×109 CFU/g,all of which meet the national standards.3.Indoor test to verify the biocontrol effect of L2 WP.The biocontrol effect of L2 WP was verified through a variety of disease control indoor experiments.Indoor tests showed that L2 WP had strong antibacterial effect on the tea anthracnose pathogen Colletotrichum gloeosporioides 1-F cultured on PDA solid medium,and the antibacterial rate was up to 1-F.The growth potential of F colony was poor.Scanning electron microscope observed that the hyphal structure of cell 1-F was seriously damaged.After spraying L2 wettable powder on the isolated tea leaves infected by the tea anthracnose pathogen 1-F bacteria cake,the incidence and disease index were significantly lower than those of the blank control,with a significant difference(p<0.05).The effect is 85.46%.Potted tea infected with 1-F spore suspension of the pathogen of tea anthracnose,after the action of L2 WP,also had a good control effect,with a control effect of 79.27%.4.Field test to verify the biocontrol effect of L2 WP.In the field test plots sprayed with L2 WP,the incidence and disease index of tea anthracnose and tea cake disease were lower than those in the water control treatment,and the difference was significant(p<0.05).The effect is 52.28%,and the average control effect on tea cake disease is 49.01%.Based on the above analysis,the L2 wettable powder prepared by optimizing the bacterial mass by fermentation has good control effect on tea anthracnose and tea cake disease,and has the effect of increasing tea yield.Therefore,this study can provide technical support for the green prevention and control of tea cake and anthracnose. |
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