|
Screening natural fruit and vegetable surface antagonistic microorganisms, to study biocontrol potential biological control technology for the development of postharvest diseases and development of bio-preservative has important guiding significance. In this study, field cultivation and marketing of melon fruit as test material, its the antagonistic microorganisms attached to the surface of a rapid screening method, and screened antagonistic strains morphology, physiology and molecular biology identification, with the best antibacterial effects strains antibacterial mechanism, the results showed that: 1, melon fruit surface is widely distributed with biocontrol potential antagonistic bacteria by growth in LB medium speed, rapid colony morphology characteristics distinguish their category; cross streaking method quickly and accurately determine the effect of the confrontation between the antagonistic bacteria and pathogens. 2, through the identification of physiological and biochemical indexes strains 16S rDNA sequences, rRNA-ITS sequence analysis and specific gene sequence amplification and interspecific genetic distance analysis melon attached to the surface of the antagonistic bacteria were identified as Bacillus amyloliquefaciens ( three morphological variants of Bacillus amyloliquefaciens) and Bacillus subtilis (Bacillus subtilis), these four categories of antagonistic bacteria are numbered: the EXWB3, EXWB1, EXWB2 and, EXWB4 3, four types of antagonistic bacteria by subculture cultured for 20 generations, maintain a stable colony morphology, these can only be to maintain the appearance of stable genetic characteristics in a particular medium, quickly identify them taxa as an important basis in LB medium. 4, four types of antagonistic bacteria for gray mold (Botrytis cinerea), the tenuis (Alternaria withalternate), Fusarium (Fusarium oxysporum), the bud sticks mildew (Cladosporium.sp) Penicillium (Penicillium.sp), Aspergillus niger ( Aspegillus niger) and pink Trichothecenes (Trichothecium roseum) showed a significant inhibitory effect of, best EXWB1 the antibacterial effect. 5, EXWB1 inhibit the three pathogenic fungus spore germination, and the destruction of their cell wall structure, causing spores deformity; the presence of live bacteria is the main reason of the antibacterial. 6, EXWB1 surfactant secretion, thereby stabilizing planting its source host and non-host fruit surface, within one month after the harvest, remained constant exogenous inoculum size antagonistic bacteria on tomato fruit adhesion amount of growth phenomenon. 7, EXWB1 processing melon fruit and inoculated with A. alterna and F. oxysporum fungus after fruit, which can effectively control the sugar content of fruit, vitamin C content, titratable acid content reduction, significantly reduced the intensity of fruit respiration and ethylene production, inhibition of infection of the pathogen on fruit as well as the expansion of the lesion. This study is the fruit surface rapid separation of antagonistic microorganisms, screening and identification of a new method, and also laid the foundation for further study of the interaction mechanism of antagonistic bacterium with pathogenic microorganisms and the development of new biological preservative.
|