A Study On Fermentation Of A168 Bacteria Against Rhizoctonia Solani

The Rhizoctonia solani is one disease of the rice production reduced. The loss of rice economy reached to millions because of its occurance. So it is very important to control the occurance of Rhizoctonia solani. At present, the method of control Rhizoctonia solani is mainly chemical control,but chemical pesticide were single apppied and was often lead to the bacteria resistance of medicine. However, the method of biological control not only saving cost high effect low toxicity but also protect envoriment,and has a beautiful prospects. The study of early day showed that the antagonist A168 against Rhizoctonia solani is exist in duck manure. The metabolites of A168 strain has a strong activation against the microbe of disease. The paper discussed the best medium, the fermentation of flask and fermenter by detector its inhibition rate to provide the basis of theory and practice for industry and agricultural. The results were as follows:1. The optimal fermentation mediumThe experiment tested the concentrations of cell density OD600 and the inhibition rate of the filtrate against Rhizoctonia solani by using the different concentration of bean-cake powder, the different concentration of glucose, the different concentration of NaCL, the different concentration of CaCO3, the different concentration of peptone, at the different concentration of condiction of the pH 7.2, inoculum 10%, inoculant age 36h, temperature 25℃, speed 200r/min, cultured 48h, repeated three times for each treatment, respectively. The results showed that:bean-cake powder 2%, glucose 7%, CaCO3 0.4%, NaCl 0.35%, peptone 6%.2 the optimal fermentation conditionsThe optimal fermentation condictions of A168 strain was discussed by concentrations of cell density OD600 and the inhibition rate of the filtrate against Rhizoctonia solani by the using the different condictions of culture time, different incubation temperature, different inoculating age, different inoculum, different speed, different medium volume, different pH parameters. The results demonstrated that the inhibition rate of A168 strain filtrate was highly at the condiction of the incubation time 48h, temperature 28℃, strain age 24h, inoculation of 6%, speed 200r/min, liquid volume was 210ml (flask 500mL), pH value of 7.0.3 the best conditions for fermentorThe best condictions of A168 strain for fermentor were tested by measured speed, ventilation, temperature and pH.. The results indicated that the inhibition rate of the A168 strain filtrate against Rhizoctonia solani was the best high at the condictions of the aeration rate 180L/h, rotate speed 200r/min,28℃, nascent pH6.5, duration 72h.. The fermentor condiction of A168 strain not only processing technology simple but also inhibiting growth of Rhizoctonia solani. The conclusion established basis of theory and practice to discovery lead compounds and large fermention.