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Comparing some genetic determinants associated with colonization of Listeria isolates within dairy plant environment.

N. Singh



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Comparing some genetic determinants associated with colonization of Listeria isolates within dairy plant environment.
N. Singh*1,2, S. Anand1,2, J. Gonzalez2, B. Kraus3. 1Midwest Dairy Foods Research Center Brookings, SD, 2South Dakota State University Brookings, SD, 3Wells Enterprises Inc Le Mars, IA.

Listeria monocytogenes is a high-risk pathogen that can colonize and persist in dairy processing plants by forming resilient biofilms. While some strains are repeatedly isolated from a plant environment, others appear to be merely transitory. The current study investigates the genetic determinants that could be associated with the biofilm-forming ability of some environmental Listeria isolates. Three isolates from the dairy processing environment, L. monocytogenes, L innocua, and L. welshimeri were compared for biofilm-forming ability on dairy floors. Small sterile chips (1 � 1 cm2) of dairy bricks were submerged in sterile dairy effluents and held at 22.5�C for 48 h to form biofilms. Swab samples drawn at the end of incubation were plated on brain heart infusion agar to enumerate biofilm-embedded cells. Means were compared using ANOVA. Our results indicate variability in the biofilm-forming ability of the 3 isolates; L. monocytogenes (log cfu 2.50 � 0.14/cm2), L. innocua (log cfu 2.72 � 0.26 /cm2), and L. welshimeri (log cfu 3.32 � 0.18/cm2). The 3 Listeria species were characterized using genetic determinants influencing colonization and biofilm formation. Genomes were assembled using CLC Genomics Workbench; resulting assemblies were used to identify MSLT types based on the Listeria monocytogenes type profile from PubMLST ( Mapping each of the isolates to the Listeria monocytogenes EGD-e reference genome discovered 110,342 high-quality single nucleotide variants (hqSNVs). The presence of genes related to capsular glycan, cell wall/ capsular LTP, biotin biosynthesis, and carbohydrate metabolism associated with amino sugars such as chitin were correlated with the biofilm formation. Further studies in this regard would help us identify the genes associated with colonization, and serve as potential targets for novel approaches such as autoinduction interrupters for preventing or limiting Listeria adhesion.

Keywords: whole-genome sequencing, biofilm, Listeria.

Biography: I am a Post Doc Research Associate at Dairy and Food Science Department at SD State University.