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United States Department of Agriculture

Agricultural Research Service

Title: Flavobacterium columnare chemotaxis to channel catfish mucus

Authors
item Klesius, Phillip
item Shoemaker, Craig
item Evans, Joyce

Submitted to: FEMS Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 15, 2008
Publication Date: October 1, 2008
Repository URL: http://hdl.handle.net/10113/43713
Citation: Klesius, P.H., Shoemaker, C.A., Evans, J.J. 2008. Flavobacterium columnare chemotaxis to channel catfish mucus. Federation of European Microbiological Societies. Microbiological Letters 288:216-220.

Interpretive Summary: Flavobacterium columnare is a Gram-negative pathogen of many species of wild and cultured fish, especially channel catfish (Ictalurus punctatus). This motile microbe is responsible for severe economic losses to the catfish industry. Flavobacterium columnare isolates from diseased channel catfish belong to either genotype I or II. Genotype II isolates were found to be more virulent than genotype I isolates. The virulent factor that may explain this difference in pathogenesis between genotype 1 and II was not identified. Skin mucus induced a greater chemotactic response by genotype II F. columnare than for genotype I F. columnare isolates. The results indicate that mucus from channel catfish triggers a chemotactic response from F. columnare. This positive chemotactic response may be an important first step for F. columnare colonization of channel catfish skin or gills and express of virulence in channel catfish

Technical Abstract: Flavobacterium columnare is a Gram-negative pathogen of many species of wild and cultured fish, especially channel catfish (Ictalurus punctatus). This motile microbe is responsible for severe economic losses to the catfish industry. Flavobacterium columnare isolates from diseased channel catfish belong to either genomovar I or II. Genomovar II isolates were found to be more virulent than genomovar I isolates. The objective of the present study determine if differences exist in the chemotactic response of these genomovars to mucus obtained from the skin, gills and intestines of healthy channel catfish using the capillary chemotaxis assay. To accomplish this objective, F. columnare motility without mucus was determined. Next, a genomovar II isolate was used to determine the chemotactic response to mucus from skin, gill and intestine. The same genomovar was used to determine the chemotactic response to skin mucus from 15 individual healthy catfish. Mucus from skin and gill induced a greater chemotactic response by F. columnare than mucus from the intestine. Sixty percent of mucus from the skin of individual catfish yielded a positive chemotactic response from F. columnare. Finally, skin mucus induced a greater chemotactic response by genomovar II F. columnare than for genomovar I F. columnare isolates. The data indicates that mucus from channel catfish results in a chemotactic response by F. columnare. This positive chemotactic response may be an important first step for F. columnare colonization of channel catfish skin or gills. Although the role that chemotaxis plays in virulence of F. columnare is not fully defined, the chemotactic response of genomovar ll isolates suggest that chemotaxis is associated with virulence.

Last Modified: 12/22/2014
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