Smith J J, McFeters G A
Department of Microbiology, Montana State University, Bozeman, USA.
J Appl Bacteriol. 1996 Feb;80(2):209-15. doi: 10.1111/j.1365-2672.1996.tb03212.x.
The effects of substrates of primary aerobic dehydrogenases, and inorganic phosphate on aerobic INT and CTC reduction in Escherichia coli were examined. In general, INT produced less formazan than CTC, but INT (+) cell counts remained near values of CTC (+) cells. INT and CTC (+) cell numbers were higher than plate counts on R2A medium using succinate, formate, lactate, casamino acids, glucose, glycerol (INT only) and no substrate. Formate resulted in the greatest amount of INT and CTC formazan. Reduction of both INT and CTC was inhibited above 10 mmol l-1 phosphate, and this appeared to be related to decreased rates of O2 consumption. Formation of fluorescent CTC (+), but not INT (+) cells was also inhibited in a concentration dependent manner by phosphate above 10 mmol l-1. From light microscopic observations it appeared CTC formed increasing amounts of poorly or non-fluorescent formazan with increasing phosphate. Therefore, use of phosphate buffer in excess of 10 mmol l-1 may not be appropriate in CTC and INT reduction assays.
研究了初级需氧脱氢酶的底物和无机磷酸盐对大肠杆菌中需氧INT和CTC还原的影响。一般来说，INT产生的甲臜比CTC少，但INT（+）细胞计数仍接近CTC（+）细胞的值。INT和CTC（+）细胞数量高于使用琥珀酸盐、甲酸盐、乳酸盐、酪蛋白氨基酸、葡萄糖、甘油（仅INT）和无底物的R2A培养基上的平板计数。甲酸盐产生的INT和CTC甲臜量最大。当磷酸盐浓度高于10 mmol l-1时，INT和CTC的还原均受到抑制，这似乎与氧气消耗速率降低有关。当磷酸盐浓度高于10 mmol l-1时，荧光CTC（+）细胞的形成也受到浓度依赖性抑制，但INT（+）细胞不受影响。从光学显微镜观察来看，随着磷酸盐浓度的增加，CTC形成的甲臜荧光越来越弱或无荧光。因此，在CTC和INT还原试验中，使用超过10 mmol l-1的磷酸盐缓冲液可能不合适。
