NOVELTY - Antagonist Bacillus subtilis strain I-23 (CGMCC NO: 4159) is new. The main biological character of the I-23 is as follows: Gram positive (G+), rod-shaped cell, spore producing, catalase positive, amylolysis positive, Voges-Proskauer reaction positive, negative in methyl red test, fibrinolysis negative, positive in gelatin hydrolysis, positive in nitride reduction test, positive in indole test, does not use citrate, produces ammonia, capable of producing air in the process of fermenting glucose and only producing acid in the process of fermenting xylose, L-arabinose and mannose.    USE - The antagonist is useful for preventing and treating Ralstonia solanacearum of potato.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) the microbial organic fertilizer for preventing and treating Ralstonia solanacearum of potato produced by the antagonist; (2)producing the microbial organic fertilizer, comprising (i) inoculating the antagonist I-23 to the modified beef extract liquid culture medium, fermenting for production under the following condition: controlling culture temperature to be 30-35 degrees C, stirring speed at 180-300 revolutions/minute, forming spore in the intermediate and late stage of fermentation, making content of bacterium or spore in the fermenting solution greater than or equal to 1x 1010 colony forming unit (cfu)/ml, (ii) making the antagonist I-23 and the mixture of pig manure compost and rapeseed meal microbial zymolyte undergo solid fermentation, adding antagonist (50 l) to each ton of solid organic material, overturning the stack once each day in solid fermenting process so as to control the fermenting temperature not to exceed 50 degrees C, fermenting for 5 days and making the content of antagonist reach more than 1x 108 cfu/g, and obtaining the microbial organic fertilizer containing the antagonist I-23, drying the microbial organic fertilizer under the condition that the temperature is not greater than 60 degrees C until the moisture content is less than 30%, packing and delivering out of the factory to be used as the microbial organic fertilizer, where, in the pig manure compost, the germinating index is more than 98%; the content of organic matter is greater than or equal to 35% by weight ratio; the content of organic nitrogen is 1.2-2% by weight ratio and the moisture content is 25-30% by weight ratio. The preparation method of the rapeseed meal microbial zymolyte comprises adding the Stenotrophomonas maltophilia strain 37-1 (CGMCC NO: 1543) fermentation solution into the rapeseed meal raw material, adjusting moisture content to 55-65% and pH to 6-7.5 for open solid fermentation, overturning the stack when the fermenting temperature is increased to 50 degrees C, overturning the stack each day to maintain the stack temperature to be 35-50 degrees C all the time, after beginning the solid fermentation continuously, increasing the pH of stack, regulating moisture content to 55-65% and pH to 6-7 by acid solution when overturning the stack each time, spraying the acid containing solution when completing the fermentation until the pH of the stack is regulated to be 5, and drying at low temperature or naturally air-drying to obtain the rapeseed meal microbial zymolyte. The preparation of the mixture of the composted pig manure compost and the rapeseed meal microbial zymolyte comprises mixing sufficiently the pig manure compost and the rapeseed meal microbial zymolyte at a ratio of 50-70%: 50-30% by volume, ripening for 2-3 days and overturning the stack twice in the after-ripening process.