University of Kragujevac, Faculty of Science, Department of Biology and Ecology, Laboratory of Microbiology, Radoja Domanovića 12, 34000 Kragujevac, Republic of Serbia.
State University of Novi Pazar, Department of Natural-Mathematical Sciences, Vuka Karadžića 9, 36300 Novi Pazar, Republic of Serbia.
Res Microbiol. 2024 Mar-Apr;175(3):104092. doi: 10.1016/j.resmic.2023.104092. Epub 2023 Jun 16.
Wastewater often contains an increased amount of mercury and, at the same time, resistant microorganisms. During wastewater treatment, a biofilm of indigenous microorganisms is often unavoidable. Therefore, the objective of this research is to isolate and identify microorganisms from wastewater and investigate their ability to form biofilms for possible application in mercury removal processes. The resistance of planktonic cells and their biofilms to the effects of mercury was investigated using Minimum Biofilm Eradication Concentration-High Throughput Plates. The formation of biofilms and the degree of resistance to mercury were confirmed in polystyrene microtiter plates with 96 wells. Biofilm on AMB Media carriers (Assisting Moving Bad Media) was quantified using the Bradford protein assay. The removal of mercury ions by biofilms formed on AMB Media carriers of selected isolates and their consortia was determined by a removal test in Erlenmeyer flasks simulating MBBR. All isolates in planktonic form showed some degree of resistance to mercury. The most resistant microorganisms (Enterobacter cloacae, Klebsiella oxytoca, Serratia odorifera, and Saccharomyces cerevisiae) were tested for their ability to form biofilms in the presence and absence of mercury, both in polystyrene plates and on ABM carriers. The results showed that among planktonic forms, K. oxytoca was the most resistant. A biofilm of the same microorganisms was more than 10-fold resistant. Most consortia biofilms had MBEC values > 100,000 μg/mL. Among individual biofilms, E. cloacae showed the highest mercury removal efficiency (97.81% for 10 days). Biofilm consortia composed of three species showed the best ability to remove mercury (96.64%-99.03% for 10 days). This study points to the importance of consortia of different types of wastewater microorganisms in the form of biofilms and suggests that they can be used to remove mercury in wastewater treatment bioreactors.
污水中通常含有更多的汞和同时具有抗性的微生物。在废水处理过程中，通常不可避免地会形成土著微生物的生物膜。因此，本研究的目的是从废水中分离和鉴定微生物，并研究它们形成生物膜的能力，以便可能应用于汞去除过程。使用最低生物膜消除浓度高通量平板研究了浮游细胞及其生物膜对汞的影响的抗性。使用聚苯乙烯微量滴定板（96 孔）确认了生物膜的形成及其对汞的抗性程度。使用 Bradford 蛋白测定法量化了 AMB 介质载体上的生物膜。通过在模拟 MBBR 的 Erlenmeyer 摇瓶中进行去除试验，确定了所选分离株及其群落形成的生物膜对 AMB 介质载体上的汞离子的去除。浮游形式的所有分离株都表现出一定程度的汞抗性。最具抗性的微生物（阴沟肠杆菌、产酸克雷伯氏菌、恶臭假单胞菌和酿酒酵母）在有和没有汞的情况下，在聚苯乙烯平板和 ABM 载体上，都被测试了形成生物膜的能力。结果表明，在浮游形式中，K. oxytoca 的抗性最强。相同微生物的生物膜的抗性超过 10 倍。大多数共生生物膜的 MBEC 值>100,000μg/mL。在单个生物膜中，E. cloacae 显示出最高的汞去除效率（10 天内为 97.81%）。由三种生物组成的生物膜共生体显示出最强的去除汞的能力（10 天内为 96.64%-99.03%）。本研究表明，不同类型废水微生物的生物膜共生体的重要性，并表明它们可用于去除废水处理生物反应器中的汞。
