Agriculture Reference
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Stability of microbiota
100
80
60
40
TVEO treated
Control
20
0
0
1
2
3
4
5
Weeks
Fig. 4.6 Microbiota stability, taking the TTGE profile of week 0 as a reference. The Cs values did not
significantly differ ( P
>
0.05). (Source: Navarrete et al . 2010b. Reproduced with permission of John Wiley
&Sons.)
of microorganisms depending on environment or to host physiological differences associated
with water salinity. To provide a broader context for their analysis, they compared fish micro-
biota data to data sets from diverse free-living and host-associated bacterial communities. This
comparison revealed that fish gut microbiota compositions are often similar to those of other
animals and contain relatively few free-living environmental bacteria. These results suggest
that the gut microbiota composition of fishes may result from host-specific selective pressures
within the gut and it could be more than a simple reflection of the microorganisms in their local
habitat or diet. This host influence is coincident with observations made in the microbiota of
rainbow trout genetic families (Navarrete et al. 2012).
4.5 CONCLUSION
In summary, present literature shows the presence of some phyla or bacterial groups in
the microbiota of fish with some evidence that core microbiota may form, to some extent,
irrespective of the rearing location or minor variations in environment and feeding regime.
This new observation in zebrafish is worthy of future investigation as similar observations
have been reported in humans, where it has been hypothesized that the human gut microbiota
can broadly be grouped into three types, termed enterotypes. LAB have been the focus of
numerous studies ( Chapter 6 ) because this group could contain common, beneficial and
potentially stable components of the microbial composition. However, microbial stability is
still an important issue and the further development of strategies to manipulate and fortify the
microbiota, such as probiotic and prebiotic applications, should help to stabilize beneficial
microbial communities and improve fish health and aquaculture productivity. It is expected
that massive sequencing methods could give more comprehensive information about the
stability and factors that influence microbiota composition, as well as to help elucidate
 
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