Department of Microbiology, Military Institute of Hygiene and Epidemiology, Kozielska 4, 01-163 Warsaw, Poland.
World J Microbiol Biotechnol. 2013 Sep;29(9):1635-43. doi: 10.1007/s11274-013-1326-0. Epub 2013 Mar 21.
Biofilm formation is a well-known problem in management of metalworking fluid systems. Due to persistence of microorganisms within biofilms, the reappearance of various species of bacteria, including nontuberculous mycobacteria is often observed after the use of biocides and/or cleaning of delivery systems and replacement of cooling fluid. The aim of this study was to determine the usefulness of the tetrazolium salt assay (MTT assay) for assessing the viability of bacteria in biofilms formed in vitro in fresh and used cutting oils, as well as their susceptibility to antimicrobial biocides. Biofilms were established in the microtiter plate format. The results showed that quantification of formazan, a product of the tetrazolium salt reduction by electron transport system could be used for determination of the propensity of bacteria to form biofilms in these complex media. The use of the assay allows also determination of antimicrobial activity of biocides against biofilms in fresh and used metalworking fluids. Biofilms produced by Gram-negative isolates recovered from field metalworking fluids as well as the wild bacterial communities differed in metabolic activity depending on the type of fresh coolants. The MTT assay has high-throughput potential and can be efficiently used for determination of biofilm-forming capacity of microorganisms from individual machines in metalworking industry. The use of the assay may also guide the selection of the most appropriate biocide to fight these microorganisms.
生物膜的形成是金属加工液系统管理中众所周知的问题。由于生物膜内微生物的持久性，在使用杀菌剂和/或清洁输送系统以及更换冷却剂后，经常会观察到各种细菌（包括非结核分枝杆菌）的再次出现。本研究的目的是确定四唑盐测定法（MTT 测定法）在评估新鲜和使用切削油中体外形成的生物膜中细菌活力及其对抗菌杀菌剂敏感性的有用性。生物膜是在微量滴定板格式中建立的。结果表明，通过电子传递系统还原的四唑盐的甲臜（formazan）产物的定量可以用于确定细菌在这些复杂介质中形成生物膜的倾向。该测定法还可用于确定新鲜和使用的金属加工液中杀菌剂对生物膜的抗菌活性。从现场金属加工液中回收的革兰氏阴性分离物以及野生细菌群落产生的生物膜在代谢活性方面因新鲜冷却剂的类型而异。MTT 测定法具有高通量的潜力，可有效地用于确定金属加工行业中来自单个机器的微生物的生物膜形成能力。该测定法的使用还可以指导选择最适合的杀菌剂来对抗这些微生物。
