Papel de las actividades superóxido dismutasa y catalasa en la ...

RESULTS AND DISCUSSION
increase superoxide anion production, does not mean that this bacterial strains cannot
stimulate another immunological parameter. In fact, survival rates, after experimental
infection, increased in fish fed with strain Pdp13. Several authors have shown that
probiotics may stimulate different immunological parameters, such as phagocytic
activity (Irianto and Austin, 2003; Panigrahi et al., 2004; Brunt and Austin, 2005; Salinas
et al., 2005; Díaz-Rosales et al., 2006), complement activity (Panigrahi et al., 2004; Díaz-
Rosales et al., 2006), lysozyme activity (Irianto and Austin, 2003; Panigrahi et al., 2004)
or cytotoxic activity (Salinas et al., 2005; Díaz-Rosales et al., 2006). Moreover, effects of
probiotics have been described on specific immune response, increasing serum
immunoglobulins levels (Nikoskelainen et al., 2003; Aubin et al., 2005). For these
reasons, strain Pdp13 can be considered as a probiotic also, although evaluation of other
immunological parameters would be necessary.
On the other hand, probiotic bacteria have to be administered at optimal doses,
depending on fish size and bacterial strain (Nikoskelainen et al., 2003), for this reason
Pdp11 effect is different to Pdp13 and the results obtained with Pdp11 and sole are
different to results previously obtained with Pdp11 and gilthead seabream (Díaz-Rosales
et al., 2006).
Finally, apart from the immunological effects of probiotics in sole immune
response, possible changes in intestinal microbiota due to probiotics were evaluated. In
spite of the great number of published works concerning microbial communities in fish
(Spanggaard et al., 2000; Holben et al., 2002; Sandaa et al., 2003; Al-Harbi and Naim
Uddin, 2004; Hjelm et al., 2004; Huber et al., 2004; Jensen et al., 2004), none of them try
to evaluate possible shifts in microbiota after probiotic administration.
In this work DGGE, Denaturing Gradient Gel Electrophoresis, (Muyzer et al.,
1993), was used to study the intestinal microbiota of soles fed with probiotics. Two sets
of primers were evaluated (Nübel et al., 1996; Jensen et al., 2004). Primers described by
Nübel et al. (1996) being selected as the best to study of bacterial communities in the
present work after analysis of banding pattern by Pearson coefficient.
The band pattern obtained was very simple, with few predominant bands, results
alike those described by Muyzer et al. (1993), who reported that communities with a few
105