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Random mutagenesis identifies novel genes involved in the secretion of antimicrobial, cell wall-lytic enzymes by Lactococcus lactis

Tan, Yu Pei, Giffard, Philip M., Barry, Daniel G., Huston, Wilhelmina M. and Turner, Mark S. (2008). Random mutagenesis identifies novel genes involved in the secretion of antimicrobial, cell wall-lytic enzymes by Lactococcus lactis. Applied and Environmental Microbiology,74(24):7490-7496.

Document type: Journal Article
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IRMA ID 10603xPUB51
Title Random mutagenesis identifies novel genes involved in the secretion of antimicrobial, cell wall-lytic enzymes by Lactococcus lactis
Author Tan, Yu Pei
Giffard, Philip M.
Barry, Daniel G.
Huston, Wilhelmina M.
Turner, Mark S.
Journal Name Applied and Environmental Microbiology
Publication Date 2008
Volume Number 74
Issue Number 24
ISSN 0099-2240   (check CDU catalogue open catalogue search in new window)
Start Page 7490
End Page 7496
Total Pages 7
Place of Publication Washington, United States
Publisher American Society for Microbiology
Field of Research 0605 - Microbiology
0799 - Other Agricultural and Veterinary Sciences
1002 - Environmental Biotechnology
HERDC Category C1 - Journal Article (DEST)
Abstract Lactococcus lactis is a Gram-positive bacterium widely used in the food industry and is therefore desirable as a candidate for the production and secretion of recombinant proteins. Previously, we generated a L. lactis strain which expressed and secreted the antimicrobial cell wall lytic enzyme lysostaphin. To identify lactococcal gene products that affect the production of lysostaphin, we isolated and characterized mutants generated by random transposon mutagenesis which had altered lysostaphin activity. Out of 35,000 mutants screened, only one with no lysostaphin activity was identified and it was found to contain an insertion in the lysostaphin expression cassette. Ten mutants with higher lysostaphin activity contained insertions in only 4 different genes which encode an uncharacterized putative transmembrane protein (llmg_0609; 3 mutants), an enzyme catalysing the first step in peptidoglycan biosynthesis (murA2; 5 mutants), a putative regulator of peptidoglycan modification (trmA; 1 mutant) and an uncharacterized enzyme possibly involved in ubiquinone biosynthesis (llmg_2148; 1 mutant). These mutants were found to secrete higher amounts of lysostaphin compared to the control strain (MG1363[lss]), and the greatest increase in secretion was 9.8 to 16.1 fold for the llmg_0609 mutants. The llmg_0609, murA2 and trmA lysostaphin oversecreting mutants were also found to secrete higher amounts another cell wall lytic enzyme (the Listeria monocytogenes bacteriophage endolysin Ply511), compared to the control strain indicating that the phenotype is not limited to lysostaphin.
Keywords Lactococcus lactis
DOI http://dx.doi.org/10.1128/AEM.00767-08   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)


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