Isolation Of Antagonistic Actinomyces Against Banana Fusarium Wilt Disease And Evaluation On Their Inhibition Effects

Banana Fusarium wilt disease is one of the External Quarantine Disease, one kind of Systemic vascular disease caused by Fusarium oxysporum f.sp. cubense, also named Panama disease or Chlorosis. By means of separation and purification from the tissues of banana tree with vascular wilt, we got the pathogen which was determined Fusarium oxysporum f.sp. cubense by Morphology and pathogenicity. This paper based on the pathogen for target, we collected rhizosphere soil samples from Dongfang, Basuo, Huangliu, Sanya in Hainan Province and Zhanjiang, Xuwen, Hai' an in Guangdong province, eventually screened the better antagonistic activity and stable actinomycetes,which was named D4-4-L.The identification,optimal fermentation conditions,the pot experiment and the control effect in the field of the strain was studied. The main results was as follows:(1) In this paper,139 strains of Antagonism Antinomyces were separated and purified from the rhizosphere soil samples which collected from Hainan Province and Guangdong province. Through Disc diffusion method,8 strains that can antagonize against F. oxysporum f.sp.cubense No.4 race were selected. Further experiments showed that 4 strains not only stably inhibit the mycelium growth of No.4 race, but also inhibit the other 14 different F. oxysporum f.sp. glycinea. In addition, mixed the fermentation supernatant from the 8 antinomyces strains with spores of F. oxysporum for 12 h, inhibition rates of 4 strains were more than 80%.(2) By means of separation and purification the tissues of banana tree with vascular wilt, the author get pathogenic bacteria of banana vascular wilt-Fusarium tip of Cuba on the 4th physiological race Fusarium oxysporum f.sp.cubense (E.F. Smith) Snyder ET Hansen. At different pH after 4-day culture, the author found that Fusarium oxysporum colony can grow in the range of pH 4.0-9.0, and the optimum ph was 6.0-7.0.The average colony diameter was among of 3.7-3.9 cm. Fusarium oxysporum in different component culture medium, test results showed that Fusarium wilt of banana in the rich spore containing N source of spores sickle bacteria growth pointed than C source. In the sixth day, Pores field of full-sugar-type culture medium was the largest, and microconidia of the best medium was the whole sugar-based medium, and the incidence of banana seedlings can reach 100%. The best medium for large conidia was the low-nitrogen-based medium.(3) Based on the culture characters,morphological characteristics,physiological and biochemical characteristics,sequence of 16S rDNA measurement and system analysis of D4-4-L strains, the results showed:D4-4-L is Streptomyces.(4) In order to improve the control effect of the ferment filtration of D4-4-L on Banana Fusarium wilt disease, using single-factor experiment design, optimize the fermentation. Using optimum medium shake fermentation tests, using optimal media conditions:10% big rice and 1.5% soybean meal, and K2HPO4 1g, NaCl 1g, CaCO3 4g, 1000ml tap water,, pH 7 and shake fermentation cultivation 6d, the will excellent for the bioactive substances accumulation.(5) The results of field plot experiment showed that the fermentation filtration of D4-4-L had better control effect on Banana Fusarium wilt disease,and the inhibition was 48.52%, which significantly higher than the hymexazol treated. The fermentation filtration of D4-4-L could increase the output of banana,the yields reached 34.68 kg/strains, and the yield rate was 21.09%,contrasted with the control.