Papel de las actividades superóxido dismutasa y catalasa en la ...
Papel de las actividades superóxido dismutasa y catalasa en la ...
Papel de las actividades superóxido dismutasa y catalasa en la ...
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Several authors have reported a stimu<strong>la</strong>tory effect of differ<strong>en</strong>t probiotics on<br />
differ<strong>en</strong>t immunological parameters, such as phagocytic [22, 24, 26, 27, 58],<br />
complem<strong>en</strong>t [24, 27], lysozyme [22, 24] or cytotoxic [26, 27] activities. Moreover it has<br />
be<strong>en</strong> <strong>de</strong>scribed that probiotic treatm<strong>en</strong>t resulted in an increase of immunoglobulin levels<br />
in serum [23, 59]. H<strong>en</strong>ce, Pdp13 strain can be consi<strong>de</strong>red as probiotic although further<br />
studies should be carried out, evaluating additional immunological aspects.<br />
On the other hand, the probiotic bacteria have to be administered at an optimal<br />
dose that may <strong>de</strong>p<strong>en</strong>d on the size and species of experim<strong>en</strong>tal fish and used probiotic<br />
strain [23]. This might exp<strong>la</strong>in differ<strong>en</strong>t effects of both probiotic strains observed in this<br />
study wh<strong>en</strong> applied to sole, and differ<strong>en</strong>ces of Pdp11 obtained for sole (this study) and<br />
gilthead seabream [27].<br />
Besi<strong>de</strong>s the effect of the probiotics on the immune response of sole, the other<br />
objective of this work was to assess changes in bacterial community structure of the sole<br />
intestine, as influ<strong>en</strong>ced by dietary treatm<strong>en</strong>t with probiotics. The <strong>de</strong>velopm<strong>en</strong>t of<br />
molecu<strong>la</strong>r methods for studying microbial communities has rec<strong>en</strong>tly also resulted in<br />
numerous works focusing on fish microbiota [20, 40-44, 60]. Nevertheless, no study has<br />
be<strong>en</strong> reported evaluating possible shifts in fish intestinal microbiota in response to<br />
probiotics administration. In the pres<strong>en</strong>t study, PCR-DGGE has be<strong>en</strong> applied to the<br />
analysis of fragm<strong>en</strong>ts <strong>de</strong>rived from differ<strong>en</strong>t hypervariable regions of 16S rRNA g<strong>en</strong>es.<br />
The set of primers selected are specific for all bacteria (V6-V8 region), and were<br />
previously used by several authors for the analysis of dietary effects on intestinal<br />
microbiota [47-49]. The results obtained in this study showed very simple patterns.<br />
Muyzer et al. [39] <strong>de</strong>scribed that communities with a few dominant species will produce<br />
simpler patterns and that less abundant species may not be a<strong>de</strong>quately repres<strong>en</strong>ted in the<br />
community pattern. It could be possible that some of these bands may not repres<strong>en</strong>t<br />
individual species, but rather groups which have the same re<strong>la</strong>tive G+C cont<strong>en</strong>t within<br />
the 16S V6-V8 region and have comigrated [61, 62]. These limitations may account in<br />
part for the <strong>de</strong>creased band number in the pres<strong>en</strong>t study and may also have influ<strong>en</strong>ced<br />
the appar<strong>en</strong>t diversity and simi<strong>la</strong>rity values [63]. The use of universal primers (e.g.<br />
those targeting the V3 or V6-V8 region of the 16S rRNA g<strong>en</strong>e) allows any bacterial<br />
community to be analyzed, although in case of an ecosystem with a re<strong>la</strong>tively high<br />
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