High intracellular expression of giant catfish growth hormone under the control of PGK promoter in Saccharomyces cerevisiae

Different yeast plasmid systems containing different promoters such as ADH1, PGK, GAPDH and GAL1, and different selectable markers, such as URA3, TRP1 and leu2-d were compared to obtain the yeast expression system that provides high intracellular expression of giant catfish growth hormone (gcGH). The highest level of gcGH expression was observed in a recombinant yeast under the control of PGK promoter (17.1 mg/l or 1.4 μg/0.1 OD). The amount of gcGH was increased six-fold (102.5 mg/l) when cells were grown in a rich medium (YEPD) with the inoculum and medium ratio of 1:1, although the amount of gcGH expression per cell density did not increase (1.0 μg/0.1 OD). This indicated that the increased yield of gcGH in rich medium was due to the increased cell density. The aim of the study was to produce high level gcGH in the cells of S. cerevisiae in order to use the yeast cells as potential feed additives to promote growth in giant catfish.[PUBLICATION ABSTRACT]