Response to low osmotic stress in a fish pathogen, Vibrio anguillarum

Abstract

Low osmotic stress responses of the fish pathogen, Vibrio anguillarum, were investigated and characterized with regard to changes in cell density and cation type in natural lake water (aged lake water, ALW) and MilliQ water (MQW). This pathogen showed higher survival (% CFU) in ALW than in MQW at all the examined cell densities (106–109 CFU ml−1). Higher resistance in ALW was partially due to divalent cations such as Ca2+ and Mg2+ present in ALW. It was also observed that addition of the supernatant, which was obtained from the pre‐suspension of V. anguillarum cells in ALW, significantly increased the survival of the pathogen in ALW. This indicated that the extracellular substance(s) released from the pathogen also played an effective role(s) for survival in ALW. Thus, divalent cations and cell density assist the pathogen, V. anguillarum, to overcome the low osmotic stress in natural freshwater environments.

A comprehensive review of Vibrio (Listonella) anguillarum: ecology, pathology and prevention

“…Vibrio anguillarum is more prevalent in nature among seedproduction environments inhabiting larval fish or rotifer populations (Sugita et al 2005) and wild-type V. anguillarum isolates are highly diverse as a result of environmental interactions when screened for their biochemical interactions, such as their reactions to malonate, methyl red, citrate, cellobiose, arabinose, indole and trehalose, which are known to vary regardless of genetic homology (Egidius & Andersen 1977). Vibrio anguillarum thrives in environments which contain divalent cations such as Ca 2+ and Mg 2+ or when the V. anguillarum population is high as opposed to low and both factors are known to contribute to the survival of the bacteria under conditions of osmotic stress (Miyamoto & Eguchi 1997). Furthermore, copper is an initiating factor of vibriosis in eel (Rødsaether et al 1977) and aquacultures stressed under elevated copper Figure 1 Immunogold electron microscopy.…”

Significance of Na+in the fish pathogen,Vibrio anguillarum, under energy depleted condition

“…V. anguillarum serotype J‐O‐1 strain M93 and V. angustum strain S14 (CCUG 15956) [16] were used. V. anguillarum M93 was originally isolated from diseased fish, Plecoglossus altivelis (Salmoniforms) in Lake Biwa, Japan, and causes vibriosis in freshwater and seawater fish [17,18]. V. angustum S14 was isolated from coastal seawater off Sydney, Australia.…”

Significance of Na+ in the fish pathogen, Vibrio anguillarum, under energy depleted condition

“…Bacterial strains and pre-culture condition V. anguillarum serotype J-O-1 strain M93 and V. angustum strain S14 (CCUG 15956) [16] were used. V. anguillarum M93 was originally isolated from diseased fish, Plecoglossus altivelis (Salmoniforms) in Lake Biwa, Japan, and causes vibriosis in freshwater and seawater fish [17,18]. V. angustum S14 was isolated from coastal seawater off Sydney, Australia.…”