Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands.
Environ Microbiol. 2018 Dec;20(12):4245-4260. doi: 10.1111/1462-2920.14305. Epub 2018 Aug 26.
Bacillus subtilis HS3 and Bacillus mycoides EC18 are two rhizosphere-associated bacteria with plant growth-promoting activity. The CRISPR-Cas9 system was implemented to study various aspects of plant-microbe interaction mechanisms of these two environmental isolates. The results show that fengycin and surfactin are involved in the antifungal activity of B. subtilis HS3. Moreover, this strain emits several other volatile organic compounds than 2,3-butanediol, contributing to plant growth promotion. Confocal laser scanning microscopy observations of the GFP-labelled strain showed that HS3 selectively colonizes root hairs of grass (Lolium perenne) in a hydroponic system. For B. mycoides EC18, we found that the wild-type EC18 strain and a ΔasbA (petropectin-deficient) mutant, but not the ΔdhbB (bacillibactin-deficient) and ADKO (asbA and dhbB double knockout) mutants, can increase the plant biomass and total chlorophyll. All the mutant strains have a reduced colonization capability on Chinese cabbage (Brassica rapa) roots, at the root tip and root hair region compared with the wild-type strain. These results indicate that the siderophore, bacillibactin, is involved in the plant growth promoting activity and could affect the root colonization of B. mycoides. Collectively, the CRISPR-Cas9 system we developed for environmental isolates is broadly applicable and will facilitate deciphering the mechanisms of Bacillus-plant interactions. © 2018 The Authors.
枯草芽孢杆菌 HS3 和粘质沙雷氏菌 EC18 是两种具有促植物生长活性的根际相关细菌。我们利用 CRISPR-Cas9 系统研究了这两种环境分离物的植物-微生物相互作用机制的各个方面。结果表明，丰原素和表面活性剂参与了枯草芽孢杆菌 HS3 的抗真菌活性。此外，该菌株还会释放出几种其他挥发性有机化合物，而不仅仅是 2,3-丁二醇，有助于促进植物生长。对 GFP 标记菌株的共焦激光扫描显微镜观察表明，HS3 选择性地定植于水培系统中草（黑麦草）的根毛。对于粘质沙雷氏菌 EC18，我们发现野生型 EC18 菌株和 ΔasbA（缺失岩藻糖脂）突变体，但不是 ΔdhbB（缺失杆菌肽）和 ADKO（asbA 和 dhbB 双缺失）突变体，可以增加植物生物量和总叶绿素。与野生型菌株相比，所有突变菌株在白菜（白菜）根上的定殖能力都有所降低，在根尖和根毛区域的定殖能力都有所降低。这些结果表明，铁载体杆菌肽参与了植物的促生长活性，并可能影响粘质沙雷氏菌的根定植。总之，我们为环境分离物开发的 CRISPR-Cas9 系统具有广泛的适用性，将有助于阐明芽孢杆菌-植物相互作用的机制。 © 2018 作者。
