Characterization of <i>Listeria monocytogenes</i> biofilm formation: A molecular approach by target gene knockout and <i>mariner</i>-based transposon mutagenesis

2010 2010

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Abstract (summary)

The food-borne pathogen Listeria monocytogenes can attach to environmental surfaces and form biofilms which can be a source of food contamination, yet little is known about the molecular mechanisms of its biofilm development. The overall objective of this study was to identify the genetic requirements of biofilm formation by L. monocytogenes.

In-frame deletion mutants of a putative mutarotase gene (lmo2476/lin2619 ) were constructed to investigate its influence on Listeria biofilm formation. No biofilm phenotype changes were observed between the wild type and the corresponding mutants, indicating that the putative mutarotase gene was not involved in Listeria biofilm formation under the conditions tested.

A mariner-based transposon mutagenesis was performed to generate mutants of L. monocytogenes. A mutant library consisting of 6,500 colonies was screened for reduced biofilm formation. A total of 24 distinct loci were identified, 18 of which, to our knowledge, have not been previously reported to function in the biofilm formation of L. monocytogenes.

A putative DNA translocase gene, lmo1386, was further characterized. The mutant was complemented, and the complemented mutant restored its biofilm phenotype. The lmo1386 mutants showed reduced initial attachment abilities, and had higher numbers of elongated cells when grown in a nutrient TSBYE broth. However, the exact mechanisms of how lmo1386 affects biofilm formation remain to be elucidated.

The inhibitory effects of EDTA against biofilm formation of L. monocytogenes were investigated. EDTA at a concentration of 0.1 mM efficiently inhibited biofilm formation of L. monocytogenes without affecting its planktonic growth. EDTA functions in the early stage by affecting the initial attachment of L. monocytogenes cells to surfaces, though the mechanisms remain unclear.

The role of extracellular DNA (eDNA) in the formation of L. monocytogenes biofilm was determined indirectly by treatments of DNase I. Our data adds to the knowledge that eDNA plays an essential role in attachment and maintenance of L. monocytogenes biofilm. The pre-formed biofilms on the wells of microtiter plates could be efficiently removed by DNase I, suggesting a potential use of DNase I to eradicate the existing L. monocytogenes biofilms.

Indexing (details)

Food Science;
0359: Food Science
0410: Microbiology
Identifier / keyword
Biological sciences; Biofilm formation; Listeria monocytogenes; Transposons
Characterization of <i>Listeria monocytogenes</i> biofilm formation: A molecular approach by target gene knockout and <i>mariner</i>-based transposon mutagenesis
Chang, Yuhua
Number of pages
Publication year
Degree date
School code
DAI-B 71/12, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
McLandsborough, Lynne A.
Committee member
Labbe, Ronald G.; Leschine, Susan B.; McClements, David J.
University of Massachusetts Amherst
Food Science
University location
United States -- Massachusetts
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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