Aleti Gajender, Lehner Sylvia, Bacher Markus, Compant Stéphane, Nikolic Branislav, Plesko Maja, Schuhmacher Rainer, Sessitsch Angela, Brader Günter
Health & Environment Department, Bioresources Unit, AIT Austrian Institute of Technology GmbH, AIT, Konrad Lorenz Strasse 24, Tulln, A-3430, Austria.
Department of Agrobiotechnology (IFA-Tulln), Center for Analytical Chemistry, University of Natural Resources and Life Sciences (BOKU), Konrad-Lorenz-Str. 20, 3430 Tulln, Austria.
Environ Microbiol. 2016 Sep;18(8):2634-45. doi: 10.1111/1462-2920.13405. Epub 2016 Jul 4.
Cyclic lipopeptides (cLP) and especially surfactins produced by Bacillus spp. trigger biofilm formation and root colonization and are crucial for biocontrol activity and systemic resistance in plants. Bacillus atrophaeus 176s isolated from the moss Tortella tortuosa produces the cLP fengycins, iturins and surfactins, possesses antifungal activities and can protect tomato, lettuce and sugar beet against Rhizoctonia solani infection. In B. atrophaeus we identified for the first time the variant surfactin C, which differs from surfactin A produced by B. subtilis and B. amyloliquefaciens by an isoleucine instead of a leucine at position 7 of the lipopeptide backbone. The analysis of the complete surfactin gene clusters revealed that the dissimilarity is encoded in the adenylation domain of srfC and show that surfactin variations are distributed in a species-specific manner in bacilli. We demonstrate that the surfactin A and C with subtle structural differences have varying signal strengths on biofilm formation and root colonization and act specifically on the respective producing strain. This became evident as biofilm formation and root colonization but not swarming motility in surfactin biosynthesis mutants was restored differentially in the presence of exogenously supplemented cognate and non-cognate surfactin variants.
环状脂肽（cLP），尤其是芽孢杆菌属产生的表面活性素，可触发生物膜形成和根部定殖，对植物的生物防治活性和系统抗性至关重要。从扭口藓中分离出的萎缩芽孢杆菌176s可产生cLP丰原素、伊枯草菌素和表面活性素，具有抗真菌活性，能保护番茄、生菜和甜菜免受立枯丝核菌感染。在萎缩芽孢杆菌中，我们首次鉴定出变体表面活性素C，它与枯草芽孢杆菌和解淀粉芽孢杆菌产生的表面活性素A的不同之处在于，脂肽主链第7位的异亮氨酸取代了亮氨酸。对完整的表面活性素基因簇的分析表明，这种差异编码在srfC的腺苷化结构域中，表明表面活性素的变异在芽孢杆菌中以物种特异性方式分布。我们证明，结构略有差异的表面活性素A和C对生物膜形成和根部定殖具有不同的信号强度，并对各自的产生菌株具有特异性作用。这在以下方面变得明显：在外源补充同源和非同源表面活性素变体的情况下，表面活性素生物合成突变体中的生物膜形成和根部定殖（而非群体运动性）以不同方式得以恢复。
