Williams C, Neithercut W D, Hossack M, Hair J, McColl K E
Department of Microbiology, Scunthorpe and Goole Hospitals Trust, Scunthorpe, UK.
FEMS Immunol Med Microbiol. 1994 Oct;9(4):273-80. doi: 10.1111/j.1574-695X.1994.tb00362.x.
The survival of Helicobacter mustelae, Proteus mirobilis, Escherichia coli and Campylobacter jejuni in the presence of urea and citrate at pH 6.0 was examined. H. mustelae, which has urease activity similar to H. pylori, had a markedly reduced survival, median 2.5% (0-78%) (P < 0.001) when incubated under these conditions. Only 7% of the ammonia produced by H. mustelae urease activity was recovered from the buffer, a similar percentage to that previously reported with H. pylori. None of the other organisms, all of which had lower urease activity, had impaired survival under these conditions. Electron microscopical studies demonstrated extensive structural damage to H. pylori following exposure to urea and citrate at pH 6.0. This structural damage to the organisms makes it unlikely that the low recovery of ammonia was due to retention of ammonia within the bacteria and suggests that the ammonia may have been incorporated into glutamate or other amino acids. Incorporation of ammonia into these compounds would deplete the cell of the key metabolic intermediate alpha-ketoglutarate and could thus explain the mechanism of the urease-dependent destruction of the organism.
研究了幽门螺杆菌、奇异变形杆菌、大肠杆菌和空肠弯曲菌在pH 6.0条件下尿素和柠檬酸盐存在时的存活情况。与幽门螺杆菌具有相似脲酶活性的鼬獾幽门螺杆菌，在这些条件下孵育时存活率显著降低，中位数为2.5%（0 - 78%）（P < 0.001）。从缓冲液中回收的鼬獾幽门螺杆菌脲酶活性产生的氨仅为7%，与先前报道的幽门螺杆菌的百分比相似。其他所有脲酶活性较低的生物体在这些条件下存活率均未受损。电子显微镜研究表明，幽门螺杆菌在pH 6.0条件下暴露于尿素和柠檬酸盐后出现广泛的结构损伤。生物体的这种结构损伤使得氨回收率低不太可能是由于氨保留在细菌内，这表明氨可能已被掺入谷氨酸或其他氨基酸中。氨掺入这些化合物会消耗细胞中的关键代谢中间体α - 酮戊二酸，从而可以解释脲酶依赖性破坏生物体的机制。
