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Physiology of detergent resistance in Enterobacter cloacae and related bacteria
Abstract
The enteric bacterium Enterobacter cloacae was grown both aerobically and anaerobically in the presence of up to 10% of the anionic detergent sodium dodecyl sulfate (SDS). However, resistance to SDS entailed a two-part energy burden. In part one, cells grown in the presence of 5-10% SDS and 5-10% sucrose or polyethylene glycol showed decreased cell yields and higher oxygen consumption. These findings suggest that the energy burden imposed by growth in 5 and 10% SDS is osmotic in origin and is attributed to SDS as a solute. In part two, a continuous energy supply was necessary to maintain cell integrity. Cells grown in SDS (0.1-10%) lysed during carbon-limited stationary phase but not during nitrogen- or phosphorus-limited stationary phase. The respiratory inhibitor KCN (3 mM) caused rapid lysis when added to aerobic log phase SDS cultures growing on glucose as the carbon source. However, when SDS (0.5%) was added 30 minutes after KCN, lysis did not occur. In aerobic cells ATP levels dropped 10 to 15-fold within 1 minute of adding KCN then increased gradually over the next 30 minutes. The addition of iodoacetic acid (2 mM), an inhibitor of glycolysis, to anaerobic log phase SDS cultures caused rapid lysis. Unlike KCN-treated aerobic cells, lysis occurred when SDS (0.5%) was added 30 minutes after addition of iodoacetic acid. In anaerobic cells ATP levels dropped 10 to 12-fold within 5 minutes of adding iodoacetic acid and did not increase over the next 30 minutes. Uptake experiments with ($\sp{14}$C) -benzoic acid and ($\sp{14}$C) -$\alpha$-isoaminobutyric acid showed that both proton gradient ($\Delta$pH) and membrane potential ($\Delta\psi$) were the same in cells grown in the presence or absence of SDS. In aerobic and anaerobic cultures the absence of a proton gradient ($\Delta$pH = 0), did not cause cell lysis. Part two of the energy dependence is attributed to SDS as a detergent. The evidence suggests that ATP, and not $\Delta$pH or $\Delta\psi$, is required for SDS resistance.
Subject Area
Microbiology|Cellular biology
Recommended Citation
Aspedon, Arden R, "Physiology of detergent resistance in Enterobacter cloacae and related bacteria" (1993). ETD collection for University of Nebraska-Lincoln. AAI9331408.
https://digitalcommons.unl.edu/dissertations/AAI9331408