Isolation and characterization of turbot (Scophtalmus maximus)-associated bacteria with inhibitory effects against Vibrio anguillarum

Abstract

More than 400 isolates from the intestine and the external surface of farmed Scophtalmus maximus as well as from fish food and hatchery water were screened for inhibitory effects against the fish pathogen Vibrio anguillarum HI 11345 and seven other fish pathogens. The bacteria with inhibitory effects were then characterized with regard to their sites of colonization, especially the intestinal regions and sites within each region. Of the total number of bacterial isolates from the intestine, 28% were inhibitory against V. anguillarum HI 11345. A marine biochemical assay was used to order the inhibitory strains into different phena. Most inhibitory bacteria were found in the rinse and mucus fractions of the gastrointestinal tract. No correlations among the different phena, site of colonization, and inhibitory effect could be found; however, a biochemical div!rsity was noted in the strains with an inhibitory effect. Of the isolates with an inhibitory effect against V. anguillarum HI 11345, 60% had an inhibitory effect on five other fish-pathogenic serotypes of V. anguillarum. Inhibitory effects of the isolates were also shown against Aeromonas salmonicida and Aeromonas hydrophila.

The probiotic potential against vibriosis of the indigenous microflora of rainbow trout

“…Most (90%) of the antagonistic bacteria were isolated from skin and gills. Westerdahl et al (1991) found that the major part of turbot bacteria inhibitory to V. anguillarum was isolated from the intestine and constituted 28% of the total flora in the turbot gut, and Sugita et al (1996;1997) reported that 2% of total flora from river fish and 1% from crab inhibited growth of V. anguillarum. Soda et al (1998) showed that 1±3.5% of the indigenous microorganisms in different microcosms (fresh water, sea water, activated sludge and soil) were inhibitory to other (exogenous) bacteria.…”

“…An intense search for indigenously occurring bacteria that can protect against fish diseases has occurred continuously for the past 10 years (Westerdahl et al, 1991;Gatesoupe, 1994;Riquelme et al, 1997;Sugita et al, 1997). Most studies of, and screenings for, probiotic bacteria have a number of underlying assumptions in common.…”

The effects of soybean, linseed and marine oils on aerobic gut microbiota of Arctic charrSalvelinus alpinusL. before and after challenge withAeromonas salmonicidassp.salmonicida

“…The production of antibacterial substances by bacteria isolated from the digestive tract of fish has been demonstrated in several studies (Schrùder, Clausen, Sandberg & Raa 1980;Strùm 1988;Westerdahl, Olsson, Kjelleberg & Conway 1991;Olsson, Westerdahl, Conway & Kjelleberg 1992;Bergh 1995;Sugita, Shibuya, Shimooka & Deguchi 1996;Jo Èborn, Olsson, Westerdahl, Conway & Kjelleberg 1997;Sugita, Shibuya, Hanada & Deguchi 1997;Gram, Melchiorsen, Spanggard, Huber & Nielsen 1999;Ringù 2000;Ringù, Bendiksen, Wesmajervi, Olsen, Jansen & Mikkelsen 2000). Therefore, the final aim was to evaluate the antibacterial potential of autochthonous bacteria isolated from the hindgut of Arctic charr before and after challenge with A. salmonicida.…”

Colonisation and transmission of lux-marked and wild-type Aeromonas salmonicida strains in Atlantic salmon (Salmo salar L.)

“…Whilst this is an innovative method to study inter-and intra-cellular associations, it is an over simpli¢cation of a complex environment. Persistence of A. salmonicida within ¢sh intestine would depend on a number of factors, including competition with, and/or inhibition by the resident micro-organisms [22,23], cellular resistance to digestive enzymes and bile salts, and penetration of the mucus layer. The absence of these factors from tissue culture systems may have in£uenced Lavelle's results.…”