Schiff L J, Morrison S M, Mayeux J V
Appl Microbiol. 1970 Nov;20(5):778-81. doi: 10.1128/am.20.5.778-781.1970.
The reported occurrence of synergistic false-positive coliform reactions on M-Endo MF medium was investigated. The objectives of the study were (i) to isolate populations of bacteria which produced such false-positive reactions, (ii) to determine whether false-positive sheen reactions are a result of synergistic interaction, and (iii) to determine the metabolic intermediates involved in false-positive sheen production. Samples of river water were subjected to coliform analysis by the membrane filter technique with M-Endo MF medium. Suspect sheen-forming colonies were analyzed to determine purity and identity of cultures. Mixed cultures were separated, and individual isolates were examined for sheen production. The isolates not producing a sheen were recombined and tested further for sheen production. Those mixtures reproducing the sheen were characterized biochemically and tested to determine the metabolic intermediates involved. Chromatographic analysis of the metabolites showed that individual isolates produced an assortment of neutral organic compounds including 2-butanone, 2,3-butanedione, formaldehyde, and butyraldehyde, whereas acetaldehyde or propionaldehyde was produced only by the mixed cultures. Tests showed that both propionaldehyde and acetaldehyde could react to produce a sheen on M-Endo medium. The conclusion was reached that synergistic false-positive coliform reactions do indeed occur on M-Endo MF medium.
对M-Endo MF培养基上协同假阳性大肠菌群反应的报道发生率进行了研究。该研究的目的是：（i）分离产生此类假阳性反应的细菌群体；（ii）确定假阳性光泽反应是否是协同相互作用的结果；（iii）确定参与假阳性光泽产生的代谢中间体。采用膜过滤技术，使用M-Endo MF培养基对河水样本进行大肠菌群分析。对可疑的产生光泽的菌落进行分析，以确定培养物的纯度和特性。分离混合培养物，并检查各个分离株是否产生光泽。将不产生光泽的分离株重新组合，并进一步测试其是否产生光泽。对重现光泽的混合物进行生化特性分析，并测试确定其中涉及的代谢中间体。代谢产物的色谱分析表明，各个分离株产生了一系列中性有机化合物，包括2-丁酮、2,3-丁二酮、甲醛和丁醛，而乙醛或丙醛仅由混合培养物产生。测试表明，丙醛和乙醛都能在M-Endo培养基上反应产生光泽。得出的结论是，M-Endo MF培养基上确实会发生协同假阳性大肠菌群反应。
