Attwood G T, Lockington R A, Xue G P, Brooker J D
Department of Animal Sciences, Waite Agricultural Research Institute, Glen Osmond, South Australia 5064.
Appl Environ Microbiol. 1988 Feb;54(2):534-9. doi: 10.1128/aem.54.2.534-539.1988.
Cloned fragments of genomic DNA from the ruminal anaerobe Bacteroides ruminicola subsp. brevis B14 were isolated and used as hybridization probes to identify closely related bacterial species. One DNA fragment unique to strain B14 was tested to determine its sensitivity in detecting homologous sequences among total ruminal microbial DNA. In a DNA titration experiment, the probe was capable of detecting strain B14 sequences in vitro down to 0.1% of the total bacterial DNA present in a hybridization assay. There was no detectable signal for total ruminal bacterial DNA. The specificity of this DNA fragment was exploited to enumerate strain B14 in a fresh mixed suspension of ruminal bacteria in vitro and after inoculation of the strain into the rumen. In vitro strain B14 had a half-life of 9 h. However, following inoculation into the rumen there was a very rapid loss of the strain to below the detectable limit within 3 h. The half-life was less than 30 min. This loss was not due to ruminal dilution or to bacteriophage attack but was possibly the result of a specific bacteriocinlike activity present in the rumen and detectable in fresh ruminal fluid.
从瘤胃厌氧菌短瘤拟杆菌亚种B14中分离出基因组DNA的克隆片段，并将其用作杂交探针来鉴定密切相关的细菌物种。对菌株B14特有的一个DNA片段进行了测试，以确定其在检测瘤胃微生物总DNA中同源序列时的灵敏度。在DNA滴定实验中，该探针能够在体外检测到杂交试验中占总细菌DNA 0.1%的菌株B14序列。瘤胃细菌总DNA未检测到信号。利用该DNA片段的特异性，对体外新鲜混合的瘤胃细菌悬液以及将该菌株接种到瘤胃后的菌株B14进行计数。体外培养时，菌株B14的半衰期为9小时。然而，接种到瘤胃后，该菌株在3小时内迅速减少至检测限以下。半衰期小于30分钟。这种减少不是由于瘤胃稀释或噬菌体攻击，而是可能是瘤胃中存在且在新鲜瘤胃液中可检测到的一种特定类细菌素活性的结果。
