Heat resistance and salt Hypersensitivity in Lactococcus lactis due to spontaneous mutation of llmg_1816 (gdpP) induced by high-temperature growth

Smith, William M., Pham, Thi Huong, Lei, Lin, Dou, Junchao, Soomro, Aijaz H., Beatson, Scott A., Dykes, Gary A. and Turner, Mark S. (2012) Heat resistance and salt Hypersensitivity in Lactococcus lactis due to spontaneous mutation of llmg_1816 (gdpP) induced by high-temperature growth. Applied and Environmental Microbiology, 78 21: 7753-7759.


Author Smith, William M.
Pham, Thi Huong
Lei, Lin
Dou, Junchao
Soomro, Aijaz H.
Beatson, Scott A.
Dykes, Gary A.
Turner, Mark S.
Title Heat resistance and salt Hypersensitivity in Lactococcus lactis due to spontaneous mutation of llmg_1816 (gdpP) induced by high-temperature growth
Formatted title Heat resistance and salt Hypersensitivity in Lactococcus lactis due to spontaneous mutation of llmg_1816 (gdpP) induced by high-temperature growth
Journal name Applied and Environmental Microbiology  (ERA 2012 Listed)    (ERA 2010 Rank A*)   Check publisher's open access policy
Publication date 2012-11
Sub-type Article
DOI 10.1128/AEM.02316-12
Volume number 78
Issue number 21
ISSN 0099-2240; 1098-5336
Start page 7753
End page 7759
Total pages 7
Place of publication Washington, DC, United States
Publisher American Society for Microbiology
Collection year 2013
Language eng
Formatted abstract During construction of several gene deletion mutants in Lactococcus lactis MG1363 which involved a high-temperature (37.5°C) incubation step, additional spontaneous mutations were observed which resulted in stable heat resistance and in some cases salt-hypersensitive phenotypes. Whole-genome sequencing of one strain which was both heat resistant and salt hypersensitive, followed by PCR and sequencing of four other mutants which shared these phenotypes, revealed independent mutations in llmg_1816 in all cases. This gene encodes a membrane-bound stress signaling protein of the GdpP family, members of which exhibit cyclic dimeric AMP (c-di-AMP)-specific phosphodiesterase activity. Mutations were predicted to lead to single amino acid substitutions or protein truncations. An independent llmg_1816 mutant (Δ1816), created using a suicide vector, also displayed heat resistance and salt hypersensitivity phenotypes which could be restored to wild-type levels following plasmid excision. L. lactis Δ1816 also displayed improved growth in response to sublethal concentrations of penicillin G. High-temperature incubation of a wild-type industrial L. lactis strain also resulted in spontaneous mutation of llmg_1816 and heat-resistant and salt-hypersensitive phenotypes, suggesting that this is not a strain-specific phenomenon and that it is independent of a plasmid integration event. Acidification of milk by the llmg_1816-altered strain was inhibited by lower salt concentrations than the parent strain. This study demonstrates that spontaneous mutations can occur during high-temperature growth of L. lactis and that inactivation of llmg_1816 leads to temperature resistance and salt hypersensitivity.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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