抗香蕉枯萎病菌拮抗菌的鉴定及其定殖

Identification and Colonization of Antagonists T2WF and W10 against Fusarium oxysporum f.sp. cubense,Pathogen of Banana Wilt Disease

通过逐步提高药物浓度方法，获得了抗利福平400μg／ml、对香蕉枯萎病菌拮抗活性稳定的T2WF和W10标记菌株。初步确定两菌株为芽孢杆菌属细菌。采用灌根接种法，在香蕉苗根际土和香蕉苗体内定殖结果表明，拮抗菌液接种浓度为5×10^4cfu／ml，两菌株均可从香蕉根际土和香蕉体内分离到，并在香蕉体内定殖和传导。在香蕉根际土、根部、球茎和假茎中，T2WF标记菌的菌量高峰分别出现在接种后5、5、11和3d，分别为707、437、273、117cfu／mg；而W10标记菌的菌量高峰分别出现在接种后5、3、5和5d，分别为784、260、253、110cfu／mg。两菌株在香蕉根际土和香蕉体内1～15d的消长动态均有一个共同的“由升到降”趋势。从数量和数量变动幅度上看，香蕉根部的菌量明显高于茎部的菌量。

Antagonistic bacteria T2WF and W10, resistant to rifampicin at 400μg/ml by continuously screening on series concentration of rifampicin media, were stable in antagonism against Fusarium oxys- porum f. sp. cubense, pathogen of banana wilt disease, and were identified as Bacillus spp.. The two marked strains could be reisolated from banana seedlings and rhizosphere soil when they were inoculated in the roots by drenching at the concentration of 5 × 10^4 cfu/ml. Results showed that strain T2WF and W10 could colonize, survive and transfer in banana seedlings. The population peaks of marked T2WF strain in rhizosphere soil root, corm and pseudostem of banana were at 5, 5, 11 and 3 d after inoculation, with numbers 707, 437, 273 and 117 cfu/mg fresh weight of soil, correspondingly. Population of strain W10 peaked at 5, 3, 5 and 5 d after inoculation with numbers 784, 260, 253 and 110 cfu/mg fresh weight of soil. Both of the strains＇ population showed the trend ＂increased at the beginning and decreased aferward＂ during 1 to 15 d after inoculation. Population of both the strains was higher in roots than in corm and pseudostem of banana seedlings.