Inhibitory Effect Of Xenorhabdus Sp.CB43 Strain And It's Antibiotic Substances Isolation And Purification

Xenorhabdus sp. CB43 strain is a symbiotical bacterium islolated from a new insect pathogenic nematodes Steinernema ceratophorum, which was isolated from Northeast China by Institute of Agricultural Environment and Sustainable Development, CAAS. Physical and chemical properties and 16srRNA analysis showed that CB43 strain was quite different from other published species, and maybe a new one. Research results showed that the metabolites oi Xenorhabdus sp. CB43 strain exhibited good antifungal activity to many pathogenic fungi especially to Botrytis cinerea. It is meaningful to isolate and identify the antibiotic substances from Xenorhabdus sp. CB43 strain and study the inhibition and the mechanism of action against Botrytis cinerea.This paper reported the inhibition and the mode of action against Botrytis cinerea. The characters and the method for separating the antibiotic substances from Xenorhabdus sp. CB43 strain was studied. The major results are as follows:1. The metabolites oi Xenorhabdus sp. CB43 strain had strong inhibition against the growth of hyphae of Botrytis cinerea. The inhibition in growth rate of hyphae was 100% at 125mL/L fermentation filtrate and had a lethal effect. 62.5 mL/L fermentation filtrate resulted in 83.35% hyphae inhibition after 72 hours of treatment. The metabolites caused abnormal branching increased and hyphae tip inflated and cytoplasm leak of B. cinerea when treated with 20mL/L metabolites. 50 62.5 mL/L fermentation filtrate inhibited sporangia germination by 88.1 —97.91% after 16 hours of treatment.2. Highly effective indicator organism Bacillus subtilis for bioassay was screened out. Results indicated that Bacillus subtilist was suitable to substitute Botrytis cinerea as an indicator organism.3. Stability of the antibiotic substances from the Xenorhabdus sp. CB43 strain in different pHs and temperatures was studied, which showed that at either 25 ℃, -20℃or 80℃, the antibiotic substances was stable in pH2¹2.4. The metabolites were water-soluble, polar and amphoteric antibiotic substances.5. The adsorbent resin H103 was screened out, which had good adsorption capacity to the microbiostatic components, and the adsorption rate was above 90%. The elution rate of the microbiostatic components in the resin H103 was at 5mL/min. The effective eluent was given as acetone solution (40%) with 0.01mol/L hydrochloric acid.6. The ion exchange resin 110 was screened out. The 3 main components were eluted at 0.2mol/L¹.8mol/L NH₄CL. UV absorption analysis revealed that component 1's UV_max was 280nm, component 2's UV_max was 216nm, and component 3's UV_max was 190²00nm. The purity of these components was detected by HPLC with 1-2 peaks.