Indigenous Lactic Acid Bacteria in Fish and Crustaceans - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 134

salmon (Strøm 1988; Jöborn et al . 1997; 1999; Ringø 2000; Ringø et al . 2000; 2006a; 2008;
Balcázar et al . 2007a; Bakke-McKellep et al . 2007; Skrodenyte-Arbaciauskiene et al . 2008;
Cantas et al . 2011). In addition, carnobacteria have been identified from Arctic charr ( Salveli-
nus alpinus L.) (Ringø and Olsen 1999; Ringø 2000; Ringø et al . 1998; 2002b; 2006b; 2006c),
river trout ( Salmo trutta fario ) (Skrodenyte-Arbaciauskiene et al . 2006) and sea trout ( Salmo
trutta trutta ) (Skrodenyte-Arbaciauskiene et al . 2008) and brown trout ( Salmo trutta )(Abid
et al . 2014).
Furthermore, some quantitative information regarding endogenous Carnobacterium
species is available. Skrodenyte-Arbaciauskiene et al . (2006) sampled the whole gut contents
(allochthonous bacteria) of river trout ( Salmo trutta fario ) and cultured isolates on tryptic
soy agar (TSA) for 3 days at 20 ∘ C. C . maltaromaticum represented 3.8% and 4.2% of the
100 isolates from trout sampled from the Skroblus river and the Zeimena river, respectively.
In laboratory reared brown trout ( Salmo trutta ) the culturable autochthonous LAB were
dominated by C . maltaromaticum ; all isolates from MRS agar from the pyloric caeca,
anterior intestine and posterior intestine were identified as C. maltaromaticum (Abid et al .
2014). Skrodenyte-Arbaciauskiene et al . (2008) sampled material from the anterior digesta
of freshwater Atlantic salmon and sea trout ( Salmo trutta trutta ) and cultured isolates on
TSA for 5 days at 17 ∘ C. The isolates from Atlantic salmon ( n = 52) and sea trout ( n = 50)
were subsequently identified by partial 16S rDNA sequencing. The results demonstrated that
Carnobacterium spp. represented 15.4% and 6.0% of the culturable heterotrophic populations
of Atlantic salmon and sea trout, respectively. These levels comprised C. maltaromaticum and
an unidentified Carnobacterium spp. in sea trout, but only C. maltaromaticum was identified
in Atlantic salmon. Ringø et al . (2008) reported Carnobacterium levels in the distal intestine
of Atlantic salmon to be of log 3.8 and 5.2 CFU g −1 for the autochthonous and allochthonous
communities, respectively. In a recent study of juvenile Atlantic salmon, Cantas et al . (2011)
investigated the culturable allochthonous intestinal microbiota of triploid and diploid fish.
Significantly higher total bacterial counts within each gut section (proximal intestine (PI),
midgut (MG) and distal intestine (DI)) were observed in triploids but a significant decrease
in Carnobacterium spp. was observed in triploids compared to diploids. Whether these
differences contribute to fish health or disease resistance has not been elucidated and merits
further investigations.
In respect of both culturable and non-culturable populations, the levels of carnobacteria in
the intestinal contents of rainbow trout are reported to be relatively low. Huber et al . (2004)
determined the microbial composition of the intestines of rainbow trout from three fish farms
by both classical culture-dependent methods (isolation on TSA after incubation at 15 ∘ Cfor
7 days) and culture-independent molecular methods (DGGE and FISH). No Carnobacterium
isolates were isolated using culture based methods or FISH from the intestine of trout at farm
1, at farm 2 or from the first visit to farm 3 (10/09/97). However, upon a second visit (09/12/97)
to farm 3 the culture based results demonstrated that Carnobacterium spp. accounted for 33%
of the culturable populations and FISH indicated that this represented 3% of total bacterial
levels. DGGE and subsequent sequencing indicated that these were C. maltaromaticum .Kim
et al . (2007) also investigated the microbial community of farm reared rainbow trout. Of the
75 culturable microorganisms isolated, the authors reported one strain of Carnobacterium sp.
and one strain belonging to C . divergens . Clone libraries derived from the intestinal contents
and intestinal mucus revealed that two out of 14 (14.3%) and one out of 31 (3.2%) clones from
intestinal contents and mucus were C . maltaromaticum . In contrast to these low levels, Pond