| Bacillus amyloliquefaciens is a kind of Gram-positive bacteria which is highly related to Bacillus subtilis, it can form the endogenous spore, has the motility and can produce a series of antimicrobial metabolites in its growth process. Bacillus amyloliquefaciens has many advantages, such as wide source, wide antimicrobial spectrum, safety and short fermentation period. It has received more and more attention in the biocontrol of postharvest diseases of fruits and vegetables. In this study, a strain of Bacillus amyloliquefaciens with high antagonistic activity against Botrytis cinerea of the postharvest pathogen of pears was isolated by plate confrontation test. The efficacy and the mechanism of Bacillus amyloliquefaciens for biocontrol gray mold of postharvest disease of pears were studied. The main results are as follows:(1) In this study, a strain of Bacillus with high antagonistic activity against Botrytis cinerea of the postharvest pathogen of pears was isolated by plate confrontation test. This strain was identified as Bacillus amyloliquefaciens through the analysis of morphological, physiological and biochemical tests and 16 S rRNA sequence, named it: Bacillus amyloliquefaciens BP30.(2) BP30 can effectively control the gray mold, when stored at 25°C for 7days, the infection rate of control was 100%, and the infection rate of pears treated by B. amyloliquefaciens was gradually decreased from the low concentration group(1×106CFU/mL) to the highest concentration group(1×108CFU/mL). It showed that the higher of the concentration of B. amyloliquefaciens was used, the lower of the infection rate and the smaller of the lesion diameter. Compared with stored at 25°C, the infection rate and the diameter of the lesion were lower when stored at 0°C for 30 days, it showed that low temperature storage is beneficial to reduce the rate of disease. Bacillus amyloliquefaciens, control of B. cinerea, had no significantly influencee on mass loss, titratable acidity, firmness and total soluble solids compared with control, but the ascorbic acid of pears was significantly higher than that of control fruits.(3) The mechanism research has proved Bacillus amyloliquefaciens BP30 play the role of inhibiting pathogenic bacteria does not through secrete antimicrobial substances. Nutrition and space competition are the main way of Bacillus amyloliquefaciens inhibition of B. cinerea; Bacillus amyloliquefaciens capable of rapid growth in the wound of pears, and occupy the space of the wound of pears, so as to play the role of inhibiting pathogenic bacteria. The biocontrol efficacy of BP30 on controlling spore germination of B. cinerea showed that the germination rate and the length of the tube of the spore that treated with Bacillus amyloliquefaciens were significantly lower than that of the control group, the strain BP30 could effectively inhibit the germination and growth of the spores. And inhibition of spore germination is perhaps one of the mechanisms of Bacillus amyloliquefaciens control gray mold. The study on inducing resistance defense mechanism showed that Bacillus amyloliquefaciens inhibited the growth of spores and at the same time, also promoted the secretion of enzymes related to the fruits itself resist disease: polyphenol oxidase(PPO), peroxidase(POD) and phenylalanine ammonia(PAL), that showed Bacillus amyloliquefaciens can cause stress reaction of pears, improve the resistance of pathogenic fungi. Improve the disease resistance of fruits may be another mechanism of Bacillus amyloliquefaciens inhibition of Botrytis cinerea.The results of the biocontrol efficiency on postharvest gray mold of pears and biocontrol mechanism of Bacillus amyloliquefaciens BP30 provided a solid theoretical basis and technical support for the biological control postharvest decay of pear. |
PDF Full Text Request