Rani Mamta, Weadge Joel T, Jabaji Suha
Department of Plant Science, Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, Canada.
Department of Biology, Wilfrid Laurier University, Waterloo, ON, Canada.
Front Microbiol. 2020 Feb 27;11:64. doi: 10.3389/fmicb.2020.00064. eCollection 2020.
Microbial biosurfactants, produced by fungi, yeast, and bacteria, are surface-active compounds with emulsifying properties that have a number of known activities, including the solubilization of microbial biofilms. In an on-going survey to uncover new or enhanced antimicrobial metabolite-producing microbes from harsh environments, such as oil-rich niches, 123 bacterial strains were isolated from three oil batteries in the region of Chauvin, Alberta, and characterized by 16S rRNA gene sequencing. Based on their nucleotide sequences, the strains are associated with 3 phyla (Actinobacteria, Proteobacteria and Firmicutes), as well as 17 other discrete genera that shared high homology with known sequences, with the majority of these strains identified to the species level. The most prevalent strains associated with the three oil wells belonged to the genus. Thirty-four of the 123 strains were identified as biosurfactant-producers, among which strain OB9 exhibited the highest biosurfactant activity based on multiple screening methods and a comparative analysis with the commercially available biosurfactant, Tween 20. OB9 was selected for further antimicrobial analysis and addition of live cultures of OB9 (or partially purified biosurfactant fractions thereof) were highly effective on biofilm disruption in agar diffusion assays against several Gram-negative food-borne bacteria and plant pathogens. Upon co-culturing with OB9, the number of either subsp. Newport SL1 or B07.007 cells significantly decreased after 6 h and were not retrieved from co-cultures following 12 h exposure. These results also translated to studies on plants, where bacterized tomato seedlings with OB9 significantly protected the tomato leaves from Newport SL1 contamination, as evidenced by a 40% reduction of log CFU of /mg leaf tissue compared to non-bacterized tomato leaves. When 0B9 was used for bacterized lettuce, the growth of B07.007, the causal agent of bacterial leaf spot of lettuce, was completely inhibited. While limited, these studies are noteworthy as they demonstrate the inhibition spectrum of 0B9 against both human and plant pathogens; thereby making this bacterium attractive for agricultural and food safety applications in a climate where microbial-biofilm persistence is an increasing problem.
由真菌、酵母和细菌产生的微生物生物表面活性剂是具有乳化特性的表面活性化合物，具有许多已知活性，包括微生物生物膜的溶解。在一项正在进行的调查中，旨在从恶劣环境（如富含石油的生态位）中发现新的或增强的产生抗菌代谢物的微生物，从艾伯塔省乔万地区的三个油库中分离出123株细菌菌株，并通过16S rRNA基因测序进行了表征。根据它们的核苷酸序列，这些菌株与3个门（放线菌门、变形菌门和厚壁菌门）以及17个与已知序列具有高度同源性的其他离散属相关，其中大多数菌株已鉴定到种水平。与三口油井相关的最普遍菌株属于该属。在123株菌株中，有34株被鉴定为生物表面活性剂生产者，其中菌株OB9基于多种筛选方法以及与市售生物表面活性剂吐温20的比较分析，表现出最高的生物表面活性剂活性。选择OB9进行进一步的抗菌分析，添加OB9的活培养物（或其部分纯化的生物表面活性剂级分）在琼脂扩散试验中对几种革兰氏阴性食源细菌和植物病原体的生物膜破坏非常有效。与OB9共培养后，新港亚种SL1或B07.007细胞的数量在6小时后显著减少，并且在暴露12小时后从共培养物中未检测到。这些结果也转化到了植物研究中，用OB9处理的番茄幼苗显著保护番茄叶片免受新港SL1污染，与未处理的番茄叶片相比，叶片组织中每毫克的对数CFU减少了40%，证明了这一点。当用0B9处理生菜时，生菜细菌性叶斑病的病原体B07.007的生长被完全抑制。虽然这些研究有限，但值得注意的是，它们证明了0B9对人类和植物病原体的抑制谱；因此，在微生物生物膜持续存在问题日益严重的环境中，这种细菌对农业和食品安全应用具有吸引力。
