Screening And Bio-control Potential Determination Of Some Antagonistic Bacteira Isolates For Controlling Anthracnose Diseases Of Mango

Mango is a rich source of nutrition and is deeply welcomed by customers all over theworld. Anthracnose, caused by Colletotrichum gloeosporioides, is the major postharvestdisease of the mango. The disease usually can cause severe damage to postharvest fruits.Traditionally, synthetic chemical fungicides or plant extracts are used for controlling thedisease, either as pre-harvest or postharvest treatments. The former bring the food safetyissues, and also lead to pathogen resistance, even pollute the environment. Biological agent isideal choice for its less usage, no residue, pollution-free and no resistance.Whereas,bio-control is considered safe and become a hot spot to control postharvest disease of fruitsand vegetables at home and abroad.There are some reports about application of antagonistic microbe to control mangoAnthracnose, but most of them are used before harvest. Postharvest control is limited to vitroexperiment. There are no effective antagonist microorganisms to control postharvest mangoanthrax at present.The purpose of study is to screening antagonistic bacteria to Colletotrichumgloeosporioides in postharvest mango, and testing its application effect.(1)The C1and B2-1strain were found to have the strongest antagonism toC.gloeosporioides by screening from mango surface, the diameter of the inhibition zonebetween C1and Colletotrichum gloeosporioides was over15mm,and the diameter of theinhibition zone between B2-1and Colletotrichum gloeosporioides was also over12mm, theyinhibited C.gloeosporioides growth with bio-control efficacies of66.52%and59.69%.(2)In vitro tests showed that the fermentation of the C1and B2-1strain or theirfermentation, and volatile metabolites and non-volatile metabolites from them inhibitedmycelia growth of C.gloeosporioides significantly. When the concentration of fermentationbroth of the C1and B2-1reach20%in the medium, the fermentation of C1and B2-1inhibitedC.gloeosporioides growth with bio-control efficacies of99.6255%and93.25%. The volatilemetabolites of fermentation broth of C1and B2-1stains inhibited C.gloeosporioides growthwith bio-control efficacies of91.76%and73.34%. The non volatile metabolites offermentation broth of C1and B2-1inhibited C.gloeosporioides growth with bio-control efficacies of100%and99.86%.(3)In vivo tests, the results showed that the fermentation broth and cell suspensions ofthe C1and B2-1strain reduced the disease incidence of mango inoculated with anthrax. Theresult of the former showed disease incidence of mango anthracnose is down to25.4%and32.8%and the latter is down to42.33%and45.50%. The disease incidence of control is100%.Both of the fermentation broth and cell suspensions also reduced the disease incidence ofmango with no vaccination, the result of the former showed disease incidence of mangoanthracnose is down to25.56%and33.33%and the latter is down to37.78%and53.33%.The disease incidence of control is83.33%. Dip treatment by the450mg/kg of Prochlorazreduced the disease incidence of mango to40.33%, not as well as the fermentation broth andcell suspensions of the C1and the fermentation broth of B2-1strain.(4)C1and B2-1were all identified as bacillus subtilis according to colony morphology,fermentation and assimilation tests and analysis. Previous studies show that not all of bacillussubtilis are safe to human beings, food security assessment of the toxicity of the fermentationfiltrate and strain screened in the test must be carried out in the further study.(5)The changes of activity of epidermal defense enzymes in mango were investigated.The results showed that the activity of PPO, POD and SOD were increased compared withcontrol. This shows that dipping treatment by antagonistic bacteria C1and B2-1can inducethe synthesis of the three defense enzymes, thereby increasing the resistance of the mango onanthrax.