The main goal of this work was to determine the effect of dietary live yeast Debaryomyces hansenii on the
enzymatic antioxidative status of sea bass Dicentrarchus labrax larvae. Growth, activity and expression of the
main antioxidative enzymes: catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD),
and heat shock protein (HSP70) were measured in sea bass larvae at 23 and 48 days after hatching. Larvae
were fed on two microdiets: group one, fed microdiet containing live yeast and the control group fed
microdiet without yeast. Heat shock protein 70 showed the same expression levels in both fish larvae fed
yeast and the control diet. The group fed D. hansenii showed highest growth and lower activity and
expression levels of GPX and SOD compared to fish fed control diet. In our work the differences in activity
and gene expression patterns could only be attributed to the presence of yeast, assuming a possible
involvement of superoxide anion retention in fish larvae, which could represent importance to the host to
increase cell or tissue responsiveness to growth- and/or differentiation-enhancing factors.