The Control Efficacy And Antibacterial Effect Of The Bacillus Strains Against Postharvest Alternaria Alternata Of Apricot And Peach

Both apricot(Armeniaca vulgaris Lam.)and peach(Amygdalus persica Linn.)are typical stone fruits,they has been widely planted in China.Due to the relatively concentrated mature period and high water content of fruit,which is infected by postharvest pathogen during storage and caused huge economic losses.In this study,the "Golden Sun" apricot and "Jinliuzaohong" super-early maturing peach were used as the test material,the antibacterial effect and antibacterial mechanism of the four Bacillus strains HB-2,X,B1 and B271 against postharvest Alternaria alternata of the postharvest pathogen of stone fruits,the effect of four Bacillus strains on the postharvest quality and induced resistance of the apricot and peach and the antibacterial activity and components analysis of volatile organic compounds of fermented broth were studied preliminarily so as to provide theoretical basis for the biological control of postharvest diseases and preservation of stone fruits.1.The injury inoculation method and plate-to-plate method has been successfully studied the antibacterial activity of the four Bacillus strains.The results showed that the fermentation broth and culture filtrate of Bacillus strains HB-2,X,B1 and B271 could significantly reduce incidence rate and effectively inhibits the diseases spot diameter of Alternaria alternate of the apricot and peach compared with the control group.2.The "Golden Sun" apricot fruit were treated with Bacillus strains fermented broth by pre-harvest spraying,the four Bacillus strains HB-2,X,B1 and B271 can significantly inhibit the rot rate of postharvest apricot and maintain fruit quality,and the effect of HB-2 and X are most significant;The Bacillus strains HB-2,X,B1 treatments by post-harvest soaking also effectively reduced the decay rate of apricot,but the effect of B271 is not significant.In addition,they also significantly delayed the decrease of vitamin C content,titratable acid content and firmness and maintained quality.The four Bacillus strains could inhibit the accumulation of malondialdehyde MDA and maintain quality while enhancing the activities of polyphenol oxidase PPO,peroxidase POD and phenylalanine ammonia lyase PAL,the disease resistance of fruits were induced and the senescence of apricot fruits were delayed after being treated with Bacillus spp.HB-2,X,B1 and B271 during storage.3.The “Jinliuzaohong” super-early maturing peach were treated with Bacillus strains fermented broth by pre-harvest spraying and post-harvest soaking,the four Bacillus strains HB-2,X,B1 and B271 can significantly inhibit the rot rate of postharvest super-early maturing peach,and they also significantly delayed the decrease of vitamin C content,titratable acid content and firmness and maintained quality.In addition,the four Bacillus strains could inhibit the accumulation of MDA and maintain quality while enhancing the activities of PPO,POD and PAL,the disease resistance of fruits were induced and the senescence of apricot fruits were delayed after being treated with Bacillus spp.HB-2,X,B1 and B271 during storage.4.The antibacterial activity of volatile organic compounds of Bacillus spp.HB-2,X and B1 fermented broth was analyzed by the two-sealed-base-plates method and headspace solid phase microextraction combined with gas chromatography-mass spectrometry(SPME-GCMS)method.The results showed that compared with the control group,the volatile organic compounds produced by three Bacillus strains fermented broth had significant inhibitory effect on the expansion of Alternaria alternata colonies with the inhibitory rate reaching to above 50%,and 28,31 and 30 kinds of compounds were identified in HB-2,B1 and X.Bacillus sp.HB-2,B1 and X would have potential application for the biological control of postharvest diseases of fruits.