Shirey J J, Bissonnette G K
Division of Plant and Soil Sciences, West Virginia University, Morgantown 26506-6057.
Can J Microbiol. 1992 Mar;38(3):261-6. doi: 10.1139/m92-044.
In vitro pure-culture studies were conducted to assess growth and sheen formation of groundwater bacteria on M-Endo medium incubated under reduced oxygen concentrations (0, 4, 8, 12, and 16%). Coliform and noncoliform bacteria were isolated from 17 untreated, rural groundwater supplies on M-Endo medium. All 16 coliform isolates tested were capable of sheen formation at oxygen concentrations of 4% or greater, yet some of these same isolates (Enterobacter aerogenes, Enterobacter cloacae, and Hafnia alvei) were either unable to grow or failed to produce a metallic sheen when incubated under strict anaerobiosis. Approximately 70% of the 21 noncoliform isolates examined exhibited growth inhibition at oxygen concentrations of 8% or less. The growth of a false-positive coliform isolate of Serratia fonticola was inhibited when incubated under reduced oxygen concentrations of 16% or less. Our findings suggest that the selectivity of M-Endo medium, and resultant inhibition of noncoliforms and false-positive coliforms, is enhanced by incubation in the absence of oxygen. However, the failure of strict anaerobiosis to permit detection of total coliforms such as Hafnia and Enterobacter spp. may compromise the reliability of this technique for evaluating the sanitary quality of some waters. On the other hand, oxygen concentrations of 4, 8, 12, and 16% permitted adequate sheen development of all coliforms tested while inhibiting some noncoliforms.
进行了体外纯培养研究，以评估在降低的氧气浓度（0%、4%、8%、12%和16%）下培养的地下水中细菌在M-远藤培养基上的生长和光泽形成情况。从17个未经处理的农村地下水供应源中，在M-远藤培养基上分离出大肠菌群和非大肠菌群细菌。所有测试的16株大肠菌群分离株在氧气浓度为4%或更高时都能够形成光泽，但其中一些相同的分离株（产气肠杆菌、阴沟肠杆菌和蜂房哈夫尼亚菌）在严格厌氧条件下培养时要么无法生长，要么无法产生金属光泽。在所检测的21株非大肠菌群分离株中，约70%在氧气浓度为8%或更低时表现出生长抑制。粘质沙雷氏菌这一假阳性大肠菌群分离株在氧气浓度降低至16%或更低时培养时生长受到抑制。我们的研究结果表明，在无氧条件下培养可增强M-远藤培养基的选择性，从而抑制非大肠菌群和假阳性大肠菌群。然而，严格厌氧条件无法检测到如哈夫尼亚菌属和肠杆菌属等所有大肠菌群，这可能会损害该技术评估某些水体卫生质量的可靠性。另一方面，4%、8%、12%和16%的氧气浓度可使所有测试的大肠菌群充分形成光泽，同时抑制一些非大肠菌群。
