Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/14/2003
Publication Date: 12/31/2003
Citation: Zhu, K., Liu, F., Liu, S., Wilkinson, B.J. 2003. Insights into growth of Listeria monocytogenes at refrigeration temperatures through studies of Tn917-induced cold-sensitive mutants [abstract]. Great Lake Regional Center of Excellence, First Annual Conference, Northwestern University, December 12-14, 2003, Chicago, Illinois. p. 25.
Technical Abstract: Listeria monocytogenes, the cause of listeriosis, is a category B priority pathogen, and is considered among food-and water-borne pathogens. The organism has the unusual ability to grow at refrigeration temperatures. We have used transposon mutagenesis to create cold-sensitive mutants as one approach to study psychrotolerance in this organism. Five thousand Tn917 insertion mutants were screened for poor growth at 4ºC. Thirty mutants were identified and the insertion site of Tn917 in 13 strains of them has been identified by cloning and sequencing. In mutants cld-1 and cld-2, Tn917 was inserted in the branched-chain -keto acid dehydrogenase gene cluster, consistent with the deficiency in branched chain fatty acids in the strains. Odd-numbered anteiso-fatty acids import an essential fluidity to the membrane of the organism permitting growth at low temperatures. Tn917 was inserted in a gene homologous to yqfF, putatively encoding an integral membrane protein in cld-14. Insertion in a variety of locations on the chromosome were found in the other cld mutants. These studies increase our knowledge of the mechanism of Listeria psychrotolerance, and will form the basis of knowledge to improve control of the organism.