Sylvius Laboratory, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands.
Arch Microbiol. 2012 Nov;194(11):893-9. doi: 10.1007/s00203-012-0823-0. Epub 2012 May 31.
In a previous study (Malfanova et al. in Microbial Biotech 4:523-532, 2011), we described the isolation and partial characterization of the biocontrol endophytic bacterium B. subtilis HC8. Using thin-layer chromatography, we have detected several bioactive antifungal compounds in the methanolic extract from the acid-precipitated supernatant of HC8. In the present study, we have further analyzed this methanolic extract using liquid chromatography-mass spectrometry. Based on the comparison of retention times and molecular masses with those of known antifungal compounds, we identified three families of lipopeptide antibiotics. These include four iturins A having fatty acyl chain lengths of C14 to C17, eight fengycins A (from C14 to C18 and from C15 to C17 containing a double bond in the acyl chain), four fengycins B (C15 to C18), and five surfactins (C12 to C16). Evaluation of the antifungal activity of the isolated lipopeptides showed that fengycins are the most active ones. To our knowledge, this is the first report of an endophytic Bacillus subtilis producing all three major families of lipopeptide antibiotics containing a very heterogeneous mixture of homologues. The questions remain open which of these lipopeptides (1) are being produced during interaction with the plant and (2) are contributing to the biocontrol activity of HC8.
在之前的研究中（Malfanova 等人，《微生物生物技术》4:523-532, 2011），我们描述了生防内生枯草芽孢杆菌 HC8 的分离和部分特性。通过薄层层析，我们在 HC8 的酸沉淀上清液的甲醇提取物中检测到几种生物活性抗真菌化合物。在本研究中，我们使用液相色谱-质谱法进一步分析了这种甲醇提取物。基于保留时间和分子量与已知抗真菌化合物的比较，我们鉴定了三类脂肽抗生素。它们包括四种具有 C14 到 C17 长链脂肪酸酰基的iturins A、八种fengycins A（从 C14 到 C18 和 C15 到 C17 含有酰链中的双键）、四种 fengycins B（C15 到 C18）和五种表面活性剂（C12 到 C16）。对分离的脂肽的抗真菌活性评估表明，fengycins 是最具活性的。据我们所知，这是首次报道内生枯草芽孢杆菌产生含有非常异构同系物混合物的所有三种主要脂肽抗生素家族。仍有两个问题尚未解决：（1）在与植物相互作用过程中产生了哪些脂肽，（2）哪些脂肽有助于 HC8 的生防活性。
