Studies On The Isolation Of Antagonism Strains Of Jerusalem Artichoke Tuber Rot Pathogenic And Characteristics Of One Marine Pseudomonas Strain

The Jerusalem artichoke (Helianthus tuberosus) is belong to Helianthus as a perennial herb, which has a strong ecological adaptability and is widely grown all around the world. As an energy crop, the Jerusalem artichoke (JA) has become a hot research field of bio-energy. It also can be used to food, fermentation for ethanol production and other industrial products. However, JA prones to rot during storage period, because of various anthropogenic and natural factors, which is a hinder to prevent the development of JA industrial scale. In order to solve the problem of JA storage rot and preservation, screening and separation the antagonistic strains of microorganisms against JA Storage rot on the point of biological control and study on what is the antagonistic mechanism preliminary, which is to provide a theoretical basis for the actual application.In this thesis, the Jerusalem artichoke (JA) variety (Nanyu No.1) tubers were rotting on Natural conditions.And then pathogen microorganisms were isolated and identified from the tubers rot. The antagonistic microbial were screened isolated depending on pathogen microorganisms of JA tuber, one of which was selected for further study to identify.To identify the characteristics of antagonism JK2strain, anlaysis culture metabolites and effect of prevention pathogen on JA slices.The main results as follows:1. There were14pathogen strains were isolated from JA rot tuber,10of which were named M1-M10, AND belonged to the fungi, four were bacterium which were named B1-B4. After morphological observation, physiological and biochemical identification, and molecular biology identifications of ITS/16S rRNA of isolated high efficient antagonistic bacteria were performed, M1-M10were found to belong to Alternaria tenuissima (M1, M3, M4, and M5), Aspergillus tamarii (M2, M10), Cladosporium tenuissimum (M6), Aspergillus fumigatus (M7), Aspergillus oryzae (M8), the Fusarium oxysporum (M9), respectively. While pathogenic bacterium were belonging to Serratia plymuthica (B1), Pseudomonas sp.(B2), Bacillus methylotrophicus (B3) and Bacillus sp.(B4).Depending on Koch principle, the test that pathogenic microorganism were inoculated back on JA tuber, fungi were mainly pathogenic for JA rot,which could be caused more than50%tuber rotting, as to bacterium were not lead to obvious disease for JA tuber. Then ten pathogenic fungi were used as objection to screening antagonistic strains.2. In the study331strains were isolated from the seawater, sea mud and mangrove mud samples which were collected from Sanya, China., There were29strains, which was screened and rescreened, with efficient antagonistic to one or more of the pathogenic M1-M10respectively. There were227strains were isolated from marine mud (sea mud and mangrove mud samples), about68.58%of the total number of strains. It included antagonistic bacteria21strains, accounting for72.41%of the total number of antagonistic strains. It was less half number isolated from seawater than marine mud, only8strains as·antagonistic were screened, by ratio of7.69%.It showed that it was closely related between the antagonistic strains and sample sources. The strain of JK2was chosed to further study for identification and antagonistic mechanism, with its highly effect of inhibitory on three of pathogenic fungi (M2, M9and M10)3. After morphological observation, physiological and biochemical identification, and molecular biology identifications of16S rRNA of JK2stain were performed, it was identified as Pseudomonas orientalis. The anti-fungi spectrum test showed that it had strong inhibition on the rice blast Jundeng and Exserohilum turcicum, and the same time could antagonistic Phytophthora capsici and Rape sclerotia, which indicted its potiental to apply for other plant pathogen. The JK2strain growth on different conditions were measured, it was founded that suitable salt concentration in the range of0-1.5%, the strain growed slowly when salinity exceeds2.0%.When the the culture temperature at the range of20-30℃, JK2bacteria growed well. But its growth is inhibited at low temperatures and the high temperature. It suited for JK2strain growth when the pH of the medium from6.0to9.0. It indicated that JK2strain was sensitive to acidic and alkaline environments.4. In order to further study the antagonistic mechanism of JK2strain, making the experiment that JK2confronted with the fungal (M2、M9and M10). Take the fungal mycelium for transmission electron microscopy, it showed that compared with the control, treatment group mycelium cell wall thickening or the irregular deformation, and organelle disintegration or even disappear, cell wall sheath deformed. JK2strains produced volatile antimicrobial substances, with the signs of treated group fungi growed slowly, and its mycelium color faded, with antagonistic rate of48.75%.There was no significant on detected activity substance from fermentation concentrate and ethyl acetate intracellular metabolites.It could not be produced activity substance in the liquid medium. While it was presumed that the active substances might be small molecular in the intracellular of JK2strain.Although, JK2strain showed inhibit the growth of pathogenic fungi spores on Jerusalem artichoke tuber slices in vivo. It speculated that JK.2strain inhibited the growth of pathogenic through secreting of volatile metabolites or small molecules signal substances.