| A lot of antagonistic bacteria strains were isolated from ginger in pathogen-free and pathogen-lighted plots of ginger wilt, Ralstonia Solanacerum in ecological conditions of Sichuan. Some bacteria with antagonism against ginger wilt that exhibited better than the others were screened by plate diffusion culture, studied on classification, fermentation, the colonization in soil, effect of growth, and biocontrol effect in field at the same time. These studies will provide some accordings for biocontrol of ginger wilt. These results were folio wings:217 bacteria strains were isolated from ginger in pathogen-free and pathogen-lighted plots in Duo-Gong country, Fei Xian-guan of Ya'an city in June 2003. Studies on inhibition experiment in vitro for primary screening , results showed that 32 strains, occupying 14.7% had antagonistic effects on ginger wilt. Among them, the diameters of 19 strains were above 1cm and occupied 59.4%. Except for the inhibiting effects of L1, D4 and T10 had better antagonistic effect on ginger wilt and the inhibiting diameters reached above 2.2cm.Except for L1, D4 and T10 they had also antagonistic effect on ginger wilt , they also could inhibited Botrytis cinerea, Sclerotinia sclerotiorum, Gibberella zeae etc, therefore they had broad-spectrum fungistatic actions.According to the physiological and biochemical characteristics, L1 was identified Bacillus cereus , D4 and T10 were identified Bacillus licheniformis.Studies on clonization experiments of L1, D4 and T10 around ginger tuber, the result showed that the last colonization density of L1 were 1.03×104cfu/g and 3.88×104cfu/g in non-sterilized soil and in sterilized soil, respectively, which were higher than that of D4 and T10 in the same conditions. L1, D4 and T10 could improve the growth of ginger, and among them L1 was the best.Studies on diseased ginger plots in field treated with different concentrations of germ suspension, the result showed that antagonists could control the damage of ginger wilt andcontrol effects was better with higher concentration. When the concentration of L1 reached 2×108cfu/ml, its control effect attained 60.1%.Chosen for its best control effect, growth curve of L1 was measured by turbidimetric method and the live bacterial counting method, it is basically matched to bacteria growth regulation . Data of logarithmic growth phase were same with the following methods.Effects of different conditions on growth of L1 and degree of inhibiting fungi activity were studied and the single factor experiment indicated that the best medium, carbon source,and nitrogen source were NYBD,glucose,beef extract and yeast extract, respectively. PH 7, 25ml at the volume of packed liquid, 64h aged bacteria inoculated and 32 °C were best for its growth and could acquire best inhibiting activity.Four factors positive mutual experiment showed that glucose, beef extract, yeast extract and NaCl as four factors, when L1 got highest inhibiting activity,composition of the best media were glucose 25g, beef extract 10g, yeast extract 5g, NaCl 11.2% and influcing degree of the four factors were yeast extract > glucose> beef extract>NaCl. When L1 growed best, glucose 20g, beef extract lOg, yeast extract 3g, NaCl 1.5%, whose influcing degree were glucose >yeast extract > NaCl > beef extract.(NH4)2SO4 preciptation was used to extract the inhibiting materials such as protein and polypeptide and the optimal saturated concentration of (NH4)2SO4 was 60%. The antagonistic peak was obtained from the extract of L1 after DEAE-52 and Sephadex G-100 column chromatography. This peak was showed only single band with 36KD in SDS-PAGE.Through analyzing the coarse protein for stability, results indicated that active materials with the function of inibiting fungi were heat tolerant water-soluble protein, and were stable at the range of pH 4-8 and had light stability. Coarse protein was mixtured with phosphate buffer at the ratio of 1:4 was the lowest inhibiting concentration.
|
PDF Full Text Request