Pawlowska Agnieszka, Sadowski Zygmunt
Department of Chemical Engineering, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland.
Microorganisms. 2020 Nov 4;8(11):1725. doi: 10.3390/microorganisms8111725.
Bacterial cell adhesion onto mineral surfaces is important in a broad spectrum of processes, including bioweathering, bioleaching, and bacterial cell transport in the soil. Despite many research efforts, a detailed explanation is still lacking. This work investigates the role of surface-active compounds, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and pure rhamnolipid (RH), in the process of bacteria attachment on the schwertmannite surface. The surface energy was calculated based on the wettability of the tested systems, and for bacteria it was 54.8 mJ/m, schwertmannite-SDS 54.4 mJ/m, schwertmannite-CTAB 55.4 mJ/m, and schwertmannite-RH 39.7 mJ/m. The total energy of adhesion estimated based on thermodynamic data was found to be negative, suggesting favorable conditions for adhesion for all examined suspensions. However, including electrostatic interactions allowed for a more precise description of bacterial adhesion under the tested conditions. The theoretical analysis using the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) approach showed a negative value of total adsorption energy only in bacteria-mineral suspensions, where SDS and rhamnolipid were added. The calculated data were in good agreement with experimental results indicating the significance of electrostatic forces in adsorption.
细菌细胞在矿物表面的附着在广泛的过程中都很重要，包括生物风化、生物浸出以及土壤中的细菌细胞运输。尽管进行了许多研究工作，但仍缺乏详细的解释。这项工作研究了表面活性化合物十六烷基三甲基溴化铵（CTAB）、十二烷基硫酸钠（SDS）和纯鼠李糖脂（RH）在细菌附着于施韦特曼石表面过程中的作用。基于测试系统的润湿性计算了表面能，细菌的表面能为54.8 mJ/m²，施韦特曼石 - SDS为54.4 mJ/m²，施韦特曼石 - CTAB为55.4 mJ/m²，施韦特曼石 - RH为39.7 mJ/m²。根据热力学数据估算的总粘附能为负值，这表明所有测试悬浮液都具备有利于粘附的条件。然而，考虑静电相互作用能更精确地描述测试条件下的细菌粘附情况。使用扩展的Derjaguin - Landau - Verwey - Overbeek（DLVO）方法进行的理论分析表明，仅在添加了SDS和鼠李糖脂的细菌 - 矿物悬浮液中，总吸附能为负值。计算数据与实验结果高度吻合，表明静电力在吸附过程中具有重要作用。
