ARS | Publication request: Attachment Strength of Listeria monocytogenes and Its Internalin Negative Mutants

Submitted to: Food Biophysics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 19, 2008
Publication Date: September 1, 2008
Citation: Chen, B.Y., Kim, T.J., Jung, Y.S., Silva, J.L. 2008. Attachment Strength of Listeria monocytogenes and Its Internalin Negative Mutants. Food Biophysics. 3:329-332.

Interpretive Summary: Contamination by the food-borne bacterial pathogen Listeria monocytogenes, the causative agent of Listeriosis, is a serious food safety issue. Attachment of L. monocytogenes to food processing surfaces can result in cross contamination of food products during processing. We examined the role of two major surface proteins (internalin A and internalin B) in the attachment process of L. monocytogenes by comparing strength of attachment to a glass surface for normal (wild-type) L. monocytogenes with mutants lacking either internalin A, internalin B, or a double mutant lacking both internalin A and B. Attachment strength was greatest for the normal L. monocytogenes, intermediate for those lacking internalin A or B, and weakest for the mutant lacking both internalin A and B. Our results indicate both internalin A and B are important in the attachment of L. monocytogenes. A better understanding of the attachment process of L. monocytogenes will allow better control of this important food pathogen.

Technical Abstract: A single cell of Listeria monocytogenes attached on food contact surfaces can be a potential source of cross-contamination in a food-processing plant. To see whether internalin A (InlA) and B (InlB), major surface proteins on L. monocytogenes, play a significant role in the attachment process, wild-type L. monocytogenes EGD (LM_EGD) and its isogenic internalin-negative mutants (LM_EGD(delta)inlA, LM_EGD(delta)inlB, and LM_EGD(delta)inlAB) were used to determine attachment strength on inert glass surface. Western blot analysis using InlA and InlB antibodies confirmed the absence of InlA in LM_EGD(delta)inlA, InlB in LM_EGD(delta)inlB, and both InlA and InlB in LM_EGD(delta)inlAB. Regardless of initial attachment numbers, LM_EGD which expressed both InlA and InlB proteins exhibited the strongest attachment strength while the double mutant (LM_EGD(delta)inlAB) exhibited the weakest. The two single mutants (LM_EGD(delta)inlA and LM_EGD(delta)inlB) that expressed only one type of the internalins were shown to have intermediate attachment strength. These results suggest that both InlA and InlB expression play a significant role in the attachment strength of L. monocytogenes on glass surface.