Institute of Biochemistry and Cell Biology, National Research Council, 80131 Naples, Italy.
Current address: TBI-INSA, 135 Avenue de Rangueil, 31400 Toulouse, France.
Mar Drugs. 2020 May 20;18(5):269. doi: 10.3390/md18050269.
Rhamnolipids (RLs) are surface-active molecules mainly produced by Antarctica is one of the less explored places on Earth and bioprospecting for novel RL producer strains represents a promising strategy for the discovery of novel structures. In the present study, 34 cultivable bacteria isolated from Edmonson Point Lake, Ross Sea, Antarctica were subjected to preliminary screening for the biosurfactant activity. The positive strains were identified by 16S rRNA gene sequencing and the produced RLs were characterized by liquid chromatography coupled to high resolution mass spectrometry (LC-HRESIMS) and liquid chromatography coupled with tandem spectrometry (LC-MS/MS), resulting in a new mixture of 17 different RL congeners, with six previously undescribed RLs. We explored the influence of the carbon source on the RL composition using 12 different raw materials, such as monosaccharides, polysaccharides and petroleum industry derivatives, reporting for the first time the production of RLs using, as sole carbon source, anthracene and benzene. Moreover, we investigated the antimicrobial potential of the RL mixture, towards a panel of both Gram-positive and Gram-negative pathogens, reporting very interesting results towards with a minimum inhibitory concentration (MIC) value of 3.13 µg/mL. Finally, we report for the first time the antimicrobial activity of RLs towards three strains of the emerging multidrug resistant with MIC values of 12.5 µg/ml.
鼠李糖脂（RLs）是一种主要由细菌产生的表面活性剂，对环境具有很好的适应性。南极是地球上探索较少的地方之一，因此，从南极环境中筛选和开发新型 RL 产生菌具有广阔的应用前景。在本研究中，对从罗斯海埃德文索普点湖分离得到的 34 株可培养细菌进行了生物表面活性剂活性的初步筛选。阳性菌株通过 16S rRNA 基因测序进行鉴定，所产生的 RLs 通过液相色谱-高分辨质谱联用（LC-HRESIMS）和液相色谱-串联质谱联用（LC-MS/MS）进行表征，结果得到了一个由 17 种不同 RL 同系物组成的新混合物，其中有 6 种是以前未描述过的 RL。我们通过使用 12 种不同的原料（如单糖、多糖和石油工业衍生物）来探索碳源对 RL 组成的影响，首次报道了使用蒽和苯作为唯一碳源生产 RL。此外，我们研究了 RL 混合物对一系列革兰氏阳性和革兰氏阴性病原体的抗菌潜力，结果表明对非常有趣，最低抑菌浓度（MIC）值为 3.13µg/mL。最后，我们首次报道了 RL 对三种耐多药铜绿假单胞菌的抗菌活性，MIC 值为 12.5µg/ml。
