The physiological basis of the Eijkman elevated-temperature test for differentiating fecal from nonfecal coliforms was investigated. Manometric studies indicated that the inhibitory effect upon growth and metabolism in a nonfecal coliform at 44.5 degrees C involved cellular components common to both aerobic and fermentative metabolism of lactose. Radioactive substrate incorporation experiments implicated cell membrane function as a principal focus for temperature sensitivity at 44.5 degrees C. A temperature increase from 35 to 44.5 degrees C drastically reduced the rates of [14C]glucose uptake in nonfecal coliforms, whereas those of fecal coliforms were essentially unchanged. In addition, relatively low levels of nonfecal coliform beta-galactosidase activity coupled with thermal inactivation of this enzyme at a comparatively low temperature may also inhibit growth and metabolism of nonfecal coliforms at the elevated temperature.
展开▼
