Studies On Antagonistic Activity Of Photosynthetic Bacterium Cs-1to Ustilaginodea Virens

Photosynthetic bacterium(PSB) is the general term of some kinds of prokaryotes which have original photosynthesis system. It widely exists in the nature of the ocean, streams, rivers, lakes, paddy fields, active sludges and soil. In recent years, the photosynthetic bacterium is widely and rapidly studied, but so far from now, the researches on its disease-resistant and antibacterial mechanism are rarely reported home and abroad.A strain cs-1which has showed resistance to Ustilaginodea virens is isolated from a pond around Hunan Academy of Agricultural Sciences. We select the strain Ustilaginodea virens0901as the tested pathogen, and according to the occurrence regularity of the rice false smut, we have preliminary discussed the bacteriostatic mechanism and related characteristics of PSB cs-1under laboratory conditions, for the purpose of providing scientific basis for the further studies on bacteriostatic mechanism of PSB and the biological control of rice false smut. The results are as follows:1.A strain is separated.The strain is identified as Rhodopseudomonas sp. According to its physiological and biochemical test and16SrDNA sequencing result, we have initially assured that this strain has a certain resistance to Ustilaginodea virens, which is named PSB cs-1.2.The fermentation supernatant of cs-1strain shows significant antagonism to Ustilaginodea virens0901:The inhibition of spore germination by fermentation supernatant stock solution is100%; When the concentration is up to70～75%, there is almost no increase in mycelium weight of Ustilaginodea virens; no sporulation, and an obvious inhibition is showed to the flat growth of Ustilaginodea virens, of which the inhibition rate can reach to57.53%; compared with CK, the mycelium of the Ustilaginodea virens is thinned and seriously fractured, the branch space of which is shorted, and the protoplast is condensed and overflowed.3.The antagonism of bacterial crushing fluid of cs-1strain showed to Ustilaginodea virens0901:The influences bacterial crushing fluid of cs-1showed to mycelium weight and sporulation ability are not so obvious:an inhibition is showed to the flat growth of Ustilaginodea virens by bacterial crushing fluid of cs-1, of which the inhibition rate can reach to45.71%.4.Choose diniconazole as the tested pesticide to Ustilaginodea virens, and discuss its indoor inhibitory effect on Ustilaginodea virens:It showed a strong inhibitory effect on Ustilaginodea virens, when its concentration exceeds3.2ug/ml, the Ustilaginodea virens stopped growing, with no increase in mycelium weight and no sporulation, whose antibacterial effect is equal to a concentration of70～75%cs-1fermentation supernatant; when the concentration is0.1ug/ml, the influence on mycelium weight is equal to a concentration of25%cs-1fermentation supernatant.5.Changes of catalase activity in rice are studied. Spray different concentration of cs-1fermentation liquid on rice which have been inoculated Ustilaginodea virens:the CAT activity changed significantly when the concentration is10×dilution, which is increased by24.54units, suggesting that cs-1fermentation liquid can improve the catalase activity in some extend, and a most obvious effect is showed with an appropriate concentration.