Laboratoire des Substances Bioactives, CBBC, 901, 2050, Hammam-lif, Tunisia.
World J Microbiol Biotechnol. 2014 Feb;30(2):529-38. doi: 10.1007/s11274-013-1471-5. Epub 2013 Aug 30.
Isolate TEB1 an antagonistic endophytic bacterium, obtained from citrus leaves and identified as Bacillus amyloliquefaciens by 16S rDNA sequencing, was used for the biological control of mal secco disease of Citrus aurantium seedlings caused by the mitosporic fungus Phoma tracheiphila. The isolate TEB1 exhibited a good in vitro activity against P. tracheiphila in dual cultures as well as with the well diffusion method. C. aurantium seedlings watered with a suspension of TEB1 cells showed a reduction of 53.61 and 48.63% in disease severity and incidence, respectively. A PCR test with specific primers was performed 365 days after inoculation and P. tracheiphila was detected along the whole stem in inoculated control plant while no amplification product was obtained in TEB1 treated seedlings. Molecular analysis of TEB1 revealed a positive amplification of fenD and ituC genes responsible of the biosynthesis of fengycin and iturin lipopeptides, respectively. Moreover, observations by optical microscope showed that TEB1 reduced by 55% the germination of P. tracheiphila conidia and exhibited a marked effect on mycelia structure. Data suggest that lipopeptides produced by the bacterium interact with the cytoplasmic membrane of the fungus causing pore formation. TEB1 appears a potential candidate for the biological control of citrus mal secco disease.
从柑橘叶片中分离到的生防拮抗内生细菌 TEB1，经 16S rDNA 测序鉴定为解淀粉芽孢杆菌（Bacillus amyloliquefaciens），用于防治由半知菌真菌梨孢拟盘多毛孢（Phoma tracheiphila）引起的柑橘黄龙病幼苗病害。在共培养和琼脂扩散法中，TEB1 对 P. tracheiphila 表现出良好的体外活性。用 TEB1 细胞悬浮液浇灌的柑橘幼苗，其病情严重度和发病率分别降低了 53.61%和 48.63%。接种后 365 天进行的 PCR 检测显示，接种对照植株的整个茎上均检测到了 P. tracheiphila，而在 TEB1 处理的幼苗中未获得扩增产物。对 TEB1 的分子分析显示，fenD 和 ituC 基因呈阳性扩增，分别负责合成丰原素和伊枯草菌素脂肽。此外，光学显微镜观察显示，TEB1 使 P. tracheiphila 分生孢子的萌发率降低了 55%，并对菌丝体结构有显著影响。数据表明，细菌产生的脂肽与真菌的细胞质膜相互作用，导致形成孔。TEB1 似乎是防治柑橘黄龙病的潜在候选生物防治剂。
