Thakare Ajinkya M, Nerurkar Anuradha S
Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Gujarat, India.
Appl Biochem Biotechnol. 2025 May 14. doi: 10.1007/s12010-025-05257-6.
Biosurfactants are amphipathic microbial products that are released extracellularly or remain attached to the cell surface. The strong biofilm anti-adhesive and anti-biofilm properties of biosurfactants make them suitable candidates for application aimed at destroying troublesome bacterial biofilm. To investigate the anti-adhesion and biofilm disruptive properties of natural rhamnolipid biosurfactant, targeted isolation of a hydrocarbonoclastic bacteria from hydrocarbon-contaminated soil of Dakor, Gujarat, India, led to the isolation of bacteria producing biosurfactant, identified as Pseudomonas aeruginosa. DKR. The orcinol test preliminarily indicated that the biosurfactant was indeed rhamnolipid. The Fourier transform infrared spectroscopy and nuclear magnetic resonance further confirmed the biosurfactant as rhamnolipid. Pseudomonas aeruginosa DKR produced 25 mg/ml rhamnolipid that reduced the surface tension to 22.4 mN/m and possessed CMC (critical micellar concentration) of 130 mg/L. Sub-inhibitory dilution (0.25 mg/ml) of purified rhamnolipid DKR demonstrated superior antiadhesive and antibiofilm properties against biofilm-forming E. coli strains isolated from drinking water coolers in comparison to subinhibitory concentrations of common chemical surfactants, chelating agents, and weak acids used. Coliphage AM isolated on selected E. coli strains as hosts also demonstrated an appreciable biofilm anti-adhesive and anti-biofilm effect at 10 Pfu/ml. This study emphasizes the utility of rhamnolipid biosurfactant DKR and Coliphage AM in lieu of chemicals as natural and eco-friendly agents in applications to eradicate biofilm from drinking water cooling containers, etc.
生物表面活性剂是两亲性微生物产物，可在细胞外释放或附着于细胞表面。生物表面活性剂强大的生物膜抗粘附和抗生物膜特性使其成为旨在破坏麻烦的细菌生物膜的应用的合适候选物。为了研究天然鼠李糖脂生物表面活性剂的抗粘附和生物膜破坏特性，从印度古吉拉特邦达科尔受烃污染的土壤中靶向分离出一种烃分解细菌，从而分离出产生生物表面活性剂的细菌，鉴定为铜绿假单胞菌DKR。间苯二酚试验初步表明该生物表面活性剂确实是鼠李糖脂。傅里叶变换红外光谱和核磁共振进一步证实该生物表面活性剂为鼠李糖脂。铜绿假单胞菌DKR产生25毫克/毫升的鼠李糖脂，可将表面张力降低至22.4毫牛顿/米，临界胶束浓度（CMC）为130毫克/升。与常用化学表面活性剂、螯合剂和弱酸的亚抑制浓度相比，纯化的鼠李糖脂DKR的亚抑制稀释液（0.25毫克/毫升）对从饮水机分离出的生物膜形成大肠杆菌菌株表现出优异的抗粘附和抗生物膜特性。以选定的大肠杆菌菌株为宿主分离出的噬菌体AM在10噬菌斑形成单位/毫升时也表现出明显的生物膜抗粘附和抗生物膜作用。本研究强调了鼠李糖脂生物表面活性剂DKR和噬菌体AM作为天然和环保剂替代化学品在从饮用水冷却容器等中根除生物膜的应用中的效用。
