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were detected at 35 dph. At 66 dph, the levels of anaerobes and aerobes decreased signifi-
cantly compared with those at 35 dph and concomitantly Lactobacillus levels increased to log
3.96 CFU g −1 larvae. The composition remained similar at 90 dph (Carnevali et al . 2004). In
a recent study, Sorroza et al . (2012) isolated and identified by 16S rRNA gene sequencing
Va. fluvialis from the gut contents of gilthead sea bream. The bacterium was subsequently
tested for its ability to inhibit in vitro growth of several fish pathogens, resistance to bile and
pH, adhesion to mucus and efficacy in a challenge study. Based on their results the authors
concluded that Va . fluvialis may be important for the control of vibriosis.
6.11 PLEURONECTIFORMES
Little information is available on LAB in the intestine of flatfish. Boulares etal . (2011) isolated
Leu . mesenteroides and Lb . brevis , and Sorroza et al . (2012) isolated Va. fluvialis from the
sole gut. In an unpublished study by Ringø, adherent C . maltaromaticum strains were isolated
from juvenile turbot intestine which inhibited the growth of A . salmonicida subsp. salmonicida
and V . anguillarum in vitro . Concerted efforts are required to focus on the identification and
functionality of indigenous LAB populations in flatfish.
6.12 CYPRINIDAE
A number of studies have focused on the indigenous gut LAB from cyprinids (Table 6.2).
6.12.1 Common carp ( Cyprinus carpio L.)
Cai et al . (1999) isolated 54 LAB strains from the intestines of common carp in the
Nakorn-Pathom Province, Thailand. These LAB belonged to the genera Leuconostoc , Ente-
rococcus , Lactobacillus , Pediococcus and Lactococcus . A later study by Jankauskiene (2002)
investigated the autochthonous and allochthonous LAB in the digestive tract of 65 carps.
Bacteria belonging to genus Lactobacillus were detected in the digesta of 42 fish (64.6% of
the fish) and associated to the wall of the digestive tract of 22 fish (33.8% of the fish). Sugita
and Mizuki (2012) evaluated the allochthonous gut microbiota in the PI and DI of common
carp reared in an indoor tank by constructing clone libraries. Of the 93 clones constructed, five
clones belonged to Lc . raffinolactis , and the results showed that there were some differences
between the two parts of the intestine investigated as Lc . raffinolactis was only detected in
the DI. Hagi et al . (2004) investigated the composition of intestinal LAB in common carp in
Kasumigaura during different seasons. During the summer, LAB levels in the GI tract were
3.3 × 10 6 CFU g −1 (ca. 0.17% of the total viable count) and comprised Lc. lactis (80% of the
LAB isolates identified) and E. seriolicida (20%). During the winter however LAB levels
were reduced to 8.0 × 10 5 CFU g −1 (ca. 1.6% of the total viable count) and were comprised
only of Lb. raffinolactis. . The study thus indicates a clear shift in culturable LAB communities
with seasonality; this was confirmed in a later study on common carp which revealed that
the predominant LAB was Lc . lactis in the summer and Lc . raffinolactis in the winter
(Hagi and Hoshino 2009). In addition, Hagi and Hoshino (2009) also isolated Enterococcus
pseudoavium , Lactobacillus fuchuensis , Lb . sakei and Leuconostoc gasicomitatum .Five
summer and five winter LAB isolates were tested with respect to growth, level of cholic acid
 
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