Study On Mechanism Of Acetic Acid Produced By Pichia Anomala0732-1 Against Bacterial Fruit Blotch

Bacterial fruit blotch(BFB)caused by Acidovorax avenae subsp.citrulli(Aac),and it is regarded as the world of devasting diseases.Our laboratory has successfully obtained a yeast strain 0732-1 that against the Aac obviously,and found short chain organic acids produced by the yeast strain 0732-1 are the key factors of the most important mechanism.Finaly,we found the acetic acid is the most important part from the short chain organic acids through the analysis.Objectives: In order to know the mechanism of the acetic acid for suppression of BFB caused by Aac.The work was done from these aspects that study the effect of acetic acid on biochemical characteristics of Aac,the influence of acetic acid on the biofilm formingability of Aac,the effection of againsting the bacterial fruit blotch from the acetic acid.Methods: We study the suppression of BFB caused by Aac from the acetic acid including the growth of bacteria,swimming ability and also the cell structure of Aac using the oxford cup method,morphology,observed the morphology of Aac by SEM;Biofilm formation of Aac affected was detected by microplates,crystal violet staining,and spectrophotometry to analysis the effect of acetic acid;Time dynamic of phenylalanine ammonialyase(PAL),catalase(CAT),peroxidase(POD)and superoxide dismutase(SOD)were detected after respective inoculating acetic acid and Aac on harm melon;Evaluating the effection of againsting the bacterial fruit blotch from the acetic acid among the hami melon seeds and leaves.Results: Acetic acid was good for increasing the suppression of Aac,the lower pH,the stronger inhibition of Aac.The strongest effection showed that the antibacterial circle diameter up to 3.2cm from the p H 2.0.Growed in the inoculum which has different pH showed that Aac was depressed,and also swimming ability by acetic acid.Bacterium cell were destroy seriously by acetic acid so that increase the pressure in the cell and change the architectonics.Aac adhered best to Luria-Bertani suface among the 11 types of carriers,and Aac formed strong biofilm in Luria-Bertani at 28 oC for 24 h.The OD was 1.30.However biofilm of Aac was decreased by acetic acid,even have no biofilm formation.The acidic environment caused by acetic acid on Aac extracellular polysaccharide also has effect.Resistancerelated enzymes of POD,SOD,PAL and CAT were highly and robust expressed by incolated with acetic acid on harm melon seedlings compared with CK,this work support the view that increased resistance-related enzymes could be involved in the mechanism against bacterial fruit.The acetic acid pH 3.0 could effectively reduce the incidence of BFB in Hami melon seedling stage.Conclusion: Through the above experiments indicate that acetic acid can inhibit the growth of Aac,and swimming ability as well other physiological and biochemical characteristics of cell structure.In addition to affect the biofilm formation of bacterial,also the influence degree increases with the decrease of acetic acid pH.Resistance-related enzymes of POD,SOD,PAL andCAT were highly and robust expressed by inculated with acetic acid pH 3.0 on harm melon seedlings compared with CK,this work support the view that increased resistance-related enzymes could be involved in the mechnism against bacterial fruit.Decrease incidence of disease seeds and improve effect of control bacterial fruit blotch by acetic acid.These improved the control effect of acetic acid produced by yeast strain 0732-1 has great application value and potential in prevention of bacterial fruit blotch.