Submitted to: Aquaculture America 2015-Book of Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/27/2014
Publication Date: N/A
Technical Abstract: Columnaris disease, caused by the bacterial pathogen Flavobacterium columnare, continues to be a major problem worldwide in cultured freshwater finfish. Despite the far-reaching negative impacts of columnaris disease, safe and efficacious preventatives and curatives for this disease remain limited. We evaluated the potential of kaolin (Al2Si205(OH)4), a type of clay, for the prevention of columnaris disease. Channel catfish (Ictalurus punctatus) fingerlings were experimentally challenged with F. columnare in untreated water or with water containing kaolin (1 g/L). Over the 7 day course of study, kaolin treatment led to significantly (P<0.001) improved survival (96%) as compared to untreated fish (78% survival). Histological examination of gill tissue revealed that kaolin-treated fish had substantially less gill damage than untreated controls. Quantitative PCR analysis of gill demonstrated that kaolin significantly reduced F. columnare adhesion (measured at 1 h post-challenge) and colonization (24 h post-challenge). Incubation of kaolin with F. columnare in vitro demonstrated that kaolin reduced the number of F. columnare cells in culture supernatants, presumably through the formation of physical complexes. In summary, kaolin can improve survival, reduce gill pathologies, and reduce bacterial attachment to key tissues associated with columnaris disease in channel catfish by binding to F. columnare.