Escherichia coli mutants resistant to inactivation by high hydrostatic pressure

Alternating cycles of exposure to high pressure and outgrowth of surviving populations were used to select for highly pressure-resistant mutants of Escherichia coli MG1655. Three barotolerant mutants (LMM1010, LMM1020, and LMM1030) were isolated independently by using outgrowth temperatures of 30, 3...

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Bibliographic Details
Published in:Applied and Environmental Microbiology 1997-03, Vol.63 (3), p.945-950
Main Authors: Hauben, K.J.A. (Katholieke Universiteit Leuven, Leuven, Belgium.), Bartlett, D.H, Soontjens, C.C.F, Cornelis, K, Wuytack, E.Y, Michiels, C.W
Format: Article
Language:English
Subjects:
Action of physical and chemical agents on bacteria
Bacteria
Bacteriology
Biological and medical sciences
Cell Membrane Permeability
ESCHERICHIA COLI
Escherichia coli - chemistry
Escherichia coli - physiology
Fatty Acids - analysis
Food industries
Food microbiology
Fundamental and applied biological sciences. Psychology
Hydrostatic Pressure
Microbiology
MUTANT
MUTANTES
Mutation
Temperature
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Summary:Alternating cycles of exposure to high pressure and outgrowth of surviving populations were used to select for highly pressure-resistant mutants of Escherichia coli MG1655. Three barotolerant mutants (LMM1010, LMM1020, and LMM1030) were isolated independently by using outgrowth temperatures of 30, 37, and 42 degrees C, respectively. Survival of these mutants after pressure treatment for 15 min at ambient temperature was 40 to 85% at 220 MPa and 0.5 to 1.5% at 800 MPa, while survival of the parent strain, MG1655, decreased from 15% at 220 MPa to 2 x 10(-8)% at 700 MPa. Heat resistance of mutants LMM1020 and LMM1030 was also altered, as evident by higher D values at 58 and 60 degrees C and reduced z values compared to those for the parent strain. D and z values for mutant LMM1010 were not significantly different from those for the parent strain. Pressure sensitivity of the mutants increased from 10 to 50 degrees C, as opposed to the parent strain, which showed a minimum around 40 degrees C. The ability of the mutants to grow at moderately elevated pressure (50 MPa) was reduced at temperatures above 37 degrees C, indicating that resistance to pressure inactivation is unrelated to barotolerant growth. The development of high levels of barotolerance as demonstrated in this work should cause concern about the safety of high-pressure food processing
ISSN:0099-2240
1098-5336
DOI:10.1128/aem.63.3.945-950.1997