Document Type
Article
Department/Program
Virginia Institute of Marine Science
Publication Date
6-1983
Journal
Applied and Environmental Microbiology
Volume
45
Issue
6
First Page
1870
Last Page
1876
DOI
Development of sublethal stress in Escherichia coli exposed in situ to estuarine waters was examined during various seasons. An electrochemical detection technique was utilized to derive a stress index based upon the difference between a predicted electrochemical response time in Trypticase soy broth or EC medium at 44.5°C estimated from a standard curve for unstressed cells and an observed response time for cells exposed to seawater. This stress index was related to recovery efficiencies of seawater-exposed cells, using a variety of standard and resuscitative enumeration procedures. Stress was further studied by determination of the adenylate energy charge. Sublethal stress as measured by the electrochemical detection method was an inverse function of water temperature, with maximum stress occurring after exposure to temperatures below 10°C. Total adenylates and ATP decreased dramatically at low temperatures, although energy charge remained relatively constant under various environmental conditions. Decreases in E. coli ATP suggest that ATP may not be an adequate measure of biomass for in situ stressed cells. Discrepancies in enumeration efficiency were most pronounced at temperatures below 10°C. Resuscitative procedures for solidmedia techniques increased the recovery of stressed cells under cold water conditions but were not as effective as the standard most-probable-number procedure.
Recommended Citation
Rhodes, MW; Anderson, Iris C.; and Kator, H, In Situ Development Of Sublethal Stress In Escherichia-Coli - Effects On Enumeration (1983). Applied and Environmental Microbiology, 45(6), 1870-1876.
Development of sublethal stress in Escherichia coli exposed in situ to estuarine waters was examined during various seasons. An electrochemical detection technique was utilized to derive a stress index based upon the difference between a predicted electrochemical response time in Trypticase soy broth or EC medium at 44.5°C estimated from a standard curve for unstressed cells and an observed response time for cells exposed to seawater. This stress index was related to recovery efficiencies of seawater-exposed cells, using a variety of standard and resuscitative enumeration procedures. Stress was further studied by determination of the adenylate energy charge. Sublethal stress as measured by the electrochemical detection method was an inverse function of water temperature, with maximum stress occurring after exposure to temperatures below 10°C. Total adenylates and ATP decreased dramatically at low temperatures, although energy charge remained relatively constant under various environmental conditions. Decreases in E. coli ATP suggest that ATP may not be an adequate measure of biomass for in situ stressed cells. Discrepancies in enumeration efficiency were most pronounced at temperatures below 10°C. Resuscitative procedures for solidmedia techniques increased the recovery of stressed cells under cold water conditions but were not as effective as the standard most-probable-number procedure.
