Effects of two closely related probiotics on respiratory burst activity of Senegalese sole (Solea senegalensis, Kaup) phagocytes, and protection against Photobacterium damselae subsp piscicida

The effects of dietary administration of two probiotics, Shewanella putrefaciens Pdp11 and Shewanella baltica Pdp13, on growth, respiratory burst activity of phagocytes of Senegalese sole (Solea senegalensis), and survival of fish challenged with Photobacterium damselae subsp. piscicida have been studied. Fish were fed for 60 days with three different diets: one control, and two diets supplemented with 10(9) cfu g(-1) of probiotics Pdp11 (Pdp11 diet) and Pdp13 (Pdp13 diet). Respiratory burst activity of phagocytes from fish fed with diet Pdp11 significantly increased after 60 days of feeding, whilst this significant increase was not detected in phagocytes from fish fed control and Pdp13 diets. On the other hand, the cumulative percentage of mortality after the challenges with P. damselae subsp. piscicida, was 100% in the groups fed with control diet, whereas mortality rates observed in the groups fed with diets supplemented with Pdp11 and Pdp13 ranged from 75-100% and 65-80%. respectively These results suggest that an increased respiratory burst activity of the phagocytes is not essential to increase the protection against the P damselae subsp. piscicida. On the other hand, the use of both probiotics improved the growth, and the survival against the pathogen, in comparison with those fish receiving the control diet. (C) 2009 Elsevier B.V. All rights reserved.