Probiotic Applications in Temperate and Warm Water Fish Species - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 260

Similar effects were observed in the dietary administration of a Sh. putrefaciens Pdp11 to
sea bream larvae (Varela etal . 2010). Under high stocking densities, an improvement in growth
performance was evident from 64 dph until the end of the experiment. In addition, most of the
metabolic parameters tested in the blood plasma, liver and muscle were comparable between
both groups, except for the muscle total α-amino acid values and the hepatic glycogen content
which were both higher in specimens fed with the probiotic (Varela et al . 2010). To test the
beneficial effects of the Sh. putrefaciens Pdp11 on stress tolerance, control specimens and fish
fed with probiotic were kept under either low (3 kg per m 3 ) or high density (30 kg per m 3 ). The
administration of probiotic Sh. putrefaciens Pdp11 in the diet promoted growth and improved
stress tolerance under high stocking density.
Similar results were previously observed by Suzer and coworkers (2008) with the use of
photosynthetic bacteria and Lactobacillus spp. (used singularly or in combination) as probiotic
supplements for gilthead sea bream. These probiotics were tested in larvae until 35 dph. The
administration during larval development was performed with live food (rotifer and Artemia ;
group 1) or with live food and water (group 2) or directly to the water (group 3). The control
group received no probiotic. Total bacterial counts among probiotic supplemented groups were
significantly different from the total bacterial counts in the controls. In addition, mean digestive
enzyme activities of all probiotic treatment groups were significantly different to that of the
control. In all probiotic treatments, the specific activities of pancreatic and intestinal enzymes
were significantly higher in larvae provided with the probiotic by live food and live food with
water but not in the group where probiotic was supplemented only by water. A significant
increase (13-105% higher) in survival was observed when the larvae were provided with the
probiotic by live food and via water. Similarly a significant increase in SGR (2-9% higher)
was observed in groups 1 and 2 where the probiotic was provided via live food. The supple-
mentation of Lactobacillus spp. directly to the tank water did not affect growth parameters and
digestive enzyme activities, and therefore administration of probiotics by this method would
not be effective in terms of husbandry parameters and nutritional condition (Suzer etal . 2008).
10.3.2 Effects on the sea bream immune system
Recent studies have evidenced that probiotic bacteria play an important role in enhancing
the immune system of adult sea bream and have direct or indirect effects on the intestinal
physiology. Such studies can be schematically subdivided into those involving the use of
monospecies and multispecies preparations or live bacteria and inactivated bacteria (Salinas
et al . 2005; 2006; 2008; Díaz-Rosales et al . 2006). In this context, Salinas et al . (2005) inves-
tigated in adult sea bream, at the systemic level, whether or not the stimulation of the innate
immune parameters prompted by the oral administration of two live bacteria in combina-
tion, Lb. delbrueckii subsp. lactis and B. subtilis , differs from that elicited by monospecies
preparations of the same probiotic candidates. The authors observed that the immunostim-
ulatory effect of the two different bacteria administered together can be more effective and
more consistent than that of the monostrain probiotic application; it was hypothesized that
mixed cultures are complementary by differently modulating host immune responses. In addi-
tion, to evaluate the effects of heat-inactivated whole bacteria on sea bream innate immune
responses, Diaz-Rosales et al . (2006) investigated the effects of dietary administration of
two heat-inactivated bacteria from the Shewanella genus ( Sh. putrefaciens Pdp11 and She-
wanella sp. 51M6, previously isolated from gilthead sea bream skin), singularly or in com-
bination for 1, 2, 3 and 4 weeks. The results showed that the two bacteria had no synergistic