Pichia pastoris expressing recombinant misgurnus anguillicaudatus growth hormone promotes the growth of M. anguillicaudatus larvae

Growth hormones (gh) can promote fish growth,however,it is extremely low in fish body and difficultly to purify. the study attempted to address this problem by introducing gene engineering technology. the his4 mutant yeast pichia pastoris gs115 strain was transformed with a constructed vector ppic9k containing misgurnus anguillicaudatus growth hormone (magh) cdna under the control of alcohol oxidase (aox1) gene promoter. pcr analysis was employed in verifying the stable integration of introduced dna. sds-page analysis indicated that recombinant m. anguillicaudatus gh (rmagh) had been expressed and exported into the culture medium after methanol induction. the production peaked at 72 h after induction,and the yield was as high as 300 mg/l in shaking-flask fermentation medium,accounting for 53% of the total secreted proteins. by feeding experiment to larvae,rmagh showed the significant growth-promoting effects in body weight and length on m. anguillicaudatus compared with the control group (p<0.01) at 6 weeks. these results were valuable to develop a new fish growth promoting agent. copyright 2014 zoological society of pakistan.