GROWTH ENHANCEMENT OF JUVENILE STRIPED MULLET BY FEEDING RECOMBINANT YEASTS CONTAINING FISH GROWTH-HORMONE

An episomal plasmid, pYERT of 7.2 kilobase pairs under the control of the glyceraldehyde-3-phosphate dehydrogenase promoter, was constructed for intracellular expression of rainbow trout growth hormone cDNA (co mplementary DNA) in the yeast Saccharomyces cerevisiae. The possibilit y that recombinant yeast containing pYERT can be orally administrated as a feedstuff additive to enhance the growth of juvenile striped mull et (Mugil cephalus) was examined. Results demonstrated that fish fed o nce daily with a basal meal containing recombinant growth hormone (rGH ) yeasts grew faster than did fish fed diets containing yeasts without rGH and fish in an untreated control group. Striped mullet fed diets with 2% rGH yeast coated with sodium alginate and gelatin showed the m ost significant differences (P < 0.01) in total weight, specific growt h rate, and feed efficiency relative to the untreated control groups a fter 4 weeks of treatment. Furthermore, the growth of fish fed the die ts with coated recombinant yeasts was better than that of fish receivi ng the same dose of uncoated yeasts. Results from this investigation s uggest that the administration of rGH yeasts in the diet is the simple st way to make the use of rGH in aquaculture economically feasible.