Peroxide sensitivity of cold‐shocked Salmonella typhimurium and Escherichia coli and its relationship to minimal medium recovery

Abstract

Cold-shocked Salmonella typhimurium displayed minimal medium recovery (MMR), viable counts on M9 minimal agar being much higher than those on tryptone soya yeast extract agar (TSYA). The addition of catalase to TSYA restored counts to the level found on M9 agar. Peroxide concentrations between 12 and 30 mumol/l were measured in TSYB but none was detected in M9 medium. Cold-shocked cells were sensitive to reagent hydrogen peroxide at a concentration similar to that found in TSYB. The minimal medium recovery phenomenon of cold-shocked cells is thus a manifestation of peroxide sensitivity. Changing the composition of growth media affected both cellular catalase activity and the magnitude of the MMR effect but the two properties were not directly related. Factors additional to cellular catalase activity must therefore affect susceptibility to peroxide following cold shock. Mutational loss of catalase, exonuclease III or recA-dependent DNA repair functions all increased the sensitivity of cold-shocked Escherichia coli to the inhibitory effects of peroxide present in rich medium. The peroxide resistant fraction of a cold-shocked population of Salm. typhimurium (i.e. those cells able to grow on TSYA) was more resistant to gamma radiation than the population as a whole. Cold shock thus sensitizes cells to more than one form of oxidative stress. Prior exposure of growing cells to 30 mumol/l hydrogen peroxide abolished their sensitivity to rich medium following cold shock implying that Salm. typhimurium contains an inducible system protecting against oxidative stress.

The Stringent Response Controls Catalases in Pseudomonas aeruginosa and Is Required for Hydrogen Peroxide and Antibiotic Tolerance

“…S2 in the supplemental material) but not in LB medium (see Fig. S2 in the supplemental material), a finding previously reported in E. coli (51,52). The reason for the decreased catalase activity in M9 medium remains unclear.…”

“…As iron limitation can significantly reduce catalase activity (68), this may explain the decreased wildtype catalase levels in M9 minimal medium. Furthermore, it has also been reported that catalase activity in E. coli decreases during growth in M9 medium, possibly due to glucose-mediated catabolite repression (51,52). Whether catabolite repression of catalases also occurs in P. aeruginosa remains unknown.…”

The Effect of Catalase on Recovery of Heat-injured DNA-repair Mutants of Escherichia coli

“…The concentration of peroxide in 10 samples of autoclaved TSB ranged from 12 to 30 PM with a mean of 20 p~. No peroxide was detected in M9 medium (Mackey & Derrick, 1986). Loss of viability of heat-injured E. coli p3478 in M9 plus 25pM-hydrogen peroxide followed a similar course to that in TSB (Fig.…”

Biotechnology-Based Methods for the Detection, Enumeration and Epidemiology of Food Poisoning and Spoilage Organisms

“…The poor recovery of UV-irradiated cells on rich growth medium was due to inhibition of this repair mechanism by amino acids. Mackey and Derrick (1986) found that cold-shocked S. typhinlurium displayed minimalmedium recovery but that addition of catalase to the rich medium restored. counts to the level found on the minimal medium.…”