Previous Article | Next Article ![]()
Appl. Environ. Microbiol., 11 1996, 4009-4013, Vol 62, No. 11
RL Buchanan and SG Edelson
Prior growth of seven enterohemorrhagic and one nonenterohemorrhagic
strains of Escherichia coli in tryptic soy broth with (TSB+G) and without
(TSB-G) 1% glucose was evaluated for its effect on acid tolerance. The
final pHs of 18-h TSB+G and TSB-G cultures were 4.6 to 5.2 and 6.9 to 7.0,
respectively. Cells were then transferred to brain heart infusion broth
adjusted to pH 2.5 or 3.0 with HCl, incubated at 37 degrees C for up to 7
h, and assayed periodically for viable populations with brain heart
infusion and MacConkey agars. All enterohemorrhagic strains were acid
resistant (< 0.5 log decline after 7 h) when initially cultured in
TSB+G, but substantial differences in acid tolerance were observed among
strains cultured in TSB-G (log declines ranged from < 0.3 to > 3.8).
The results indicated that prior growth in a medium with and without a
fermentable carbohydrate is a convenient way to studying the induction of
acid tolerance, that acid inactivation is preceded by a period of acid
injury, and that pH- independent and pH-dependent stationary-phase acid
tolerance phenotypes may exist among strains of enterohemorrhagic E. coli.
Copyright © 1996, American Society for Microbiology
Culturing enterohemorrhagic Escherichia coli in the presence and absence of glucose as a simple means of evaluating the acid tolerance of stationary-phase cells
Food Safety Research Unit, U.S. Department of Agriculture, Eastern Regional Research Center, Wyndmoor, Pennsylvania 19038, USA. rbuchanan@arserrc.gov
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»