PhD Thesis MJProl .pdf - digital-csic Digital CSIC - Consejo Superior ...

Abstract
In small scale trials conducted under larval rearing conditions and different
nutrients levels, matured Phaeobacter 27-4 ceramic biofilters reduced the concentration
of L. anguillarum 90-11-287 and total Vibrionaceae in green seawater with different
nutrients levels.
Phaeobacter 27-4 biofilters significantly reduced a 45 % the accumulated
mortality in turbot larvae infected with the pathogen L. anguillarum 90-11-287 by
diminishing pathogen levels and the concentration of total Vibrionaceae, mainly in
seawater. Additionally, the probiotic biofilter reduced turbidity in the rearing tanks.
DGGE analysis revealed that the incorporation of L. anguillarum or Phaeobacter
matured biofilters did not displace or modify significantly the bacterial microbiota
present on larvae, which showed low bacterial diversity. However, the presence of
Phaeobacter biofilters diminished the carrying capacity in seawater of rearing tanks.
The shifts occurring in the bacterial community of turbot larvae reflected the influence
of rotifers on larvae bacterial communities, whereas in the seawater shifts were marked
by disappearance of bands when Phaeobacter biofilters were present.
Biofilters acted as a probiotic reservoir in the rearing system, maintaining the
level of the probiotic in the seawater of tanks for at least ten days, period in which
larvae are fed on rotifers and which is considered critical for larval survival. An
important advantage of this biofilters is that their use does not require repeated additions
of the probiotic, avoiding long-term cultures and bioencapsulation in rotifers. This
feature simplifies the potential transference of this methodology to industrial hatcheries.
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