Agriculture Reference
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approximately 10
4
CFU g
−1
. Strøm and Olafsen (1990) investigated the gut microbiota of four
Atlantic cod groups: wild caught fry (group 1), fry held in a fish farm for one month (group
2), fish fed an artificial diet for one year (group 3) and fish sampled from a farm after an out-
break of cold water vibriosis (group 4). The results of this study showed that the proportion of
mucosal
Lactobacillus
was affected by feeding regimes. The highest proportion of
Lactobacil-
lus
(constituting 30% of the culturable microbiota) was detected in the gut of group 3 and 10%
was reported in group 1 and in group 4. Surprisingly,
Lactobacillus
accounted for
1% of the
gut microbiota in group 2. In a later study, Strøm and Ringø (1993) reported that lactobacilli
constituted
<
1% of the gut microbiota in 14-day-old cod larvae. However, it should be noted
that the larvae were not fed during the 14 day experiment.
The study of Ringø
et al
. (2006c) investigated the allochthonous and autochthonous micro-
biota in the PI, MG and hindgut chamber (HC; fermentation chamber) of 1-year-old Atlantic
cod fed fishmeal, standard soybean meal and a bioprocessed soybean meal. The results demon-
strated that the gut microbiota was modulated by dietary manipulation. The only LAB isolated
in this study belonged to
Carnobacterium
sp., identified by 16S rRNA gene sequencing, and
was generally detected as both allochthonous and autochthonous in all three segments of the
GI tract of fish fed fishmeal and soybean meal. However, the
Carnobacterium
sp. was less
abundant in the GI tract of bioprocessed soybean meal fed fish.
Seppola
et al
. (2006) isolated allochthonous and autochthonous LAB from the DI and HC
of fed and starved (3 days) cod. All strains isolated from the HC belonged to carnobacteria, in
contrast to the DI where only 10.2% of the isolates were carnobacteria. Lauzon
et al
. (2010)
reported
Lc
.
lactis
ssp.
lactis
,
Va. fluvialis
and
Enterococcus pseudoavium
in the gut of cod
larvae. Løvmo Martinsen
et al
. (2011) observed that
C
.
maltaromaticum
constituted a minor
part of the bacterial community (5 × 10
3
CFU g
−1
) in the MG of cod. Askarian
et al
. (2013)
isolated a
Carnobacterium
sp. from the GI tract of cod which displayed protease and cellu-
lase activities and some phytase activity and inhibited
in vitro
growth of
A
.
salmonicida
,
V
.
anguillarum
,
Moritella viscosa
(the causative agent of winter ulcer) and a pathogenic
C
.
mal-
taromaticum
.
Zhou
et al
. (2012) investigated the autochthonous gut microbiota of cod fed diets with or
without 5% chitin supplementation using DGGE. From each of the two dietary groups, samples
were taken from the PI and DI of three individual fish. The results revealed
Lactococcus
sp. in
both segments of both dietary groups, independent of the dietary treatment, whereas
Lc
.
lactis
was only detected in the DI of the chitin fed group.
Information on the LAB in the GI tract of saithe (
Pollachius virens
L.) is reported by
Schrøder
et al
. (1980), Strøm (1988) and Strøm and Ringø (unpublished results). In the early
study of Schrøder and co-authors a
Lb. plantarum
-like strain was isolated from the GI tract.
However, the strain was only identified by physiological and biochemical characterization, but
as it grew at pH below 5.5 it possible that it belonged to genus
Lactobacillus
. The strain grew
well at low temperature and inhibited the growth of
Vibrio
sp. In the studies of Strøm (1988)
and Strøm and Ringø (unpublished results), autochthonous LAB, present at approximately
10
4
CFU g
−1
, were isolated from the intestine of saithe. These isolates were identified as
C
.
divergens
and
C
.
maltaromaticum
based on 16S rRNA gene sequencing (Ringø and Strøm
unpublished results).
In a study carried out on 12 fish species, wild and farmed, from various fishing grounds in
Tunisia, Boulares
et al
. (2011) isolated
Lb
.
brevis
from whiting (
Merlangius merlangus
) and
reported that the bacterium was dominant among the culturable LAB in the intestine.
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