Inactivation of a Cold-Induced Putative RNA Helicase Gene of Listeria monocytogenes Is Accompanied by Failure To Grow at Low Temperatures but Does Not Affect Freeze-Thaw Tolerance
Abstract:Freeze-thaw tolerance (cryotolerance) of Listeria monocytogenes is markedly influenced by temperature of growth of the bacteria, and may involve responses to low-temperature stresses encountered during freezing and thawing. A cold-sensitive mariner-based transposon mutant of L. monocytogenes F2365 was found to harbor a single insertion in LMOf2365_1746, encoding a putative RNA helicase, and earlier shown by other investigators to be induced during 4°C growth of L. monocytogenes. The mutant had normal growth at 37°C but completely failed to grow at either 4 or 10°C, and had impaired growth and reduced swarming on soft agar at 25°C. However, the mutation had no discernible influence on the ability of the bacteria to tolerate repeated freezing and thawing after growth at either 25 or 37°C. The findings suggest that the transposon insertion in the putative helicase gene, in spite of the severely cold-sensitive phenotype that accompanies it, does not affect the ability of the bacteria to cope with cold-related stresses encountered during repeated freezing and thawing.
Document Type: Research Article
Affiliations: Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA
Publication date: August 1, 2010
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