Indigenous Lactic Acid Bacteria in Fish and Crustaceans - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 144

(oesophagus, stomach, PI and DI) in beluga and Persian sturgeon. Mean LAB levels in beluga
and Persian sturgeons were 7.9 × 10 6 CFU g −1 and 5.4 × 10 6 CFU g −1 , respectively. Maximum
LAB levels were reported in the DI of beluga (3.8 × 10 6 CFU g −1 ) and Persian sturgeon (4.6
× 10 6 CFU g −1 ) while minimum levels were present in the PI (3.2 × 10 5 CFU g −1 in beluga
and 1.1 × 10 5 CFU g −1 in Persian sturgeon). 16S rRNA partial sequencing of LAB isolates
( n = 70) from beluga and Persian sturgeon revealed that 25 isolates were identified (98-99%
sequence alignment) as Lb. curvatus , eight isolates as Lactococcus raffinolactis, , five isolates
as Lc. lactis spp. cremoris , and two isolates as Streptococcus spp. Furthermore, in Persian
sturgeon 22 isolates were identified as Leu . mesenteroides and eight isolates as Enterococcus
seriolicida . Based on these results, the authors concluded that the DI is the best region for
isolating LAB in the GI tract of beluga and Persian sturgeon and that the LAB community
composition differed between the species (Askarian et al . 2009). It was interesting to note
therefore that, in a later study, Askarian et al . (2011) observed that dietary administration of
Lb . curvatus (isolated by Askarian et al . 2009) improved the growth performance and diges-
tive enzyme activities of beluga whereas the application of Leu . mesenteroides (isolated by
Askarian et al . 2009) did not. In contrast, in Siberian sturgeon Leu . mesenteroides applica-
tion improved the growth performance and digestive enzyme activities but Lb . curvatus did
not. These studies would infer that the dominant LAB communities in these sturgeon species
display host specificity and that they might have important influences on the host.
Ghanbari et al . (2009) isolated and characterized LAB from intestine of beluga and Persian
sturgeons inhabiting the Caspian Sea using culture based techniques followed by biochem-
ical tests. Their results showed relatively high levels of LAB in the intestine of beluga (log
5.3 CFU g −1 ) and Persian sturgeon (log 6.4 CFU g −1 ). Biochemical tests of the gut isolates
indicated prevalence of Lb. sakei , Lb. plantarum , Lb. alimentarius , Lb. casei in beluga and Lb.
sakei and Lb. brevis in Persian sturgeon. In a more recent study, Soltani et al . (2013) reported
that culturable autochthonous LAB ranged from log 2.93 to 5.61 CFU g −1 intestine in Persian
sturgeon. 16S rRNA gene sequence analysis revealed that the LAB community was dominated
by Lc . garvieae and Lc . lactis . In addition the authors reported that Pediococcus pentosaceus ,
W . cibaria and E. faecalis were minor components of the LAB community.
Characterization of indigenous microbiota, especially LAB, using culture-independent
molecular approaches like PCR-DGGE, next-generation sequencing and FISH, which provide
a more comprehensive assessment of bacterial communities, has so far been neglected in stur-
geon studies. Thus, determination of indigenous LAB and their levels in different life stages
of sturgeon species, for the development of optimum prebiotic and probiotic applications, is
an obvious topic for future research.
6.8 PERCIDAE AND SCIAENIDAE
It has been demonstrated that LAB species are members of the normal microbiota of some Per-
cidae (Bucio et al . 2006) and Sciaenidae (Sica et al . 2010). Lb. coryneformis subsp . torquens ,
Lb.sakei , Biidobacteriumdentium and lactobacilli have been isolated from perch ( Percaluvi-
atilis ) (Bucio et al . 2006; Vlková et al . 2012), Lactobacillus spp. from ruffe ( Gymnocephalus
cernuus ) (Bucio etal . 2006), W . viridescens and Leu.mesenteroides subsp .mesenteroides from
stripped weakfish ( Cynoscion guatucupa ) (Sica et al . 2010) and Leu. mesenteroides subsp .
mesenteroides from Micropogonias furnieri (Sica et al . 2010).