Survival and infectivity of Flexibacter columnaris in the presence of other competing bacteria
1991
Chowdhury, M.B.R. | Wakabayashi, H. (Tokyo Univ., (Japan). Faculty of Agriculture, Dept. of Fisheries)
Survival and infectivity of Flexibacter columnaris in the presence of Pseudomonas fluorescens, Streptococcus sp., Flavobacterium flavescens or Flavobacterium fuscum were investigated. The presence of P. fluorescens, at an initial number 10 times that of F. columnaris, caused rapid decline in survival of F. columnaris. The pathogen, F. columnaris could neither produce any signs of disease in experimental fish (loach, Misgurnus angullicaudatus) nor cause mortality when the number of P. fluorescens was 100 times higher than F. columnaris. The fraction of F. columnaris among total bacteria in the mucus of fish body surface did not markedly increase. In contrast, survival of F. columnaris in the presence of either Streptococcus sp., F. flavescens, or F. fuscum did not significantly decline even after 7 days. In the presence of these bacteria, F. columnaris successfully invaded the fish producing typical columnaris lesions on the body surface and caused mortality even when the competing bacteria were 1,000 times in excess. In this case, percentage of F. columnaris among the total bacteria in the mucus of fish body surface gradually increased.
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