Feeding strategy design for recombinant human growth hormone production by Bacillus subtilis.

Abstract

Defined and semi-defined medium-based feeding strategies were developed to enhance recombinant human growth hormone (rhGH) production by Bacillus subtilis BGSC-1A178 (scoC (-)) strain carrying pMK4::pre(subC)::hGH. Defined medium-based feeding strategies were designed by exponential feeding of glucose and (NH4)2HPO4 at two pre-determined specific growth rates, µ 0=0.10 and 0.17h(-1). Semi-defined medium-based feeding strategies were designed by exponential feeding of substrate solution consisting of glucose, (NH4)2HPO4, peptone, and tracesalt solution (PTM1) at three pre-determined specific growth rates, µ 0=0.10, 0.17, and 0.25h(-1). At all the strategies applied, transition cultivation time from batch to fed-batch operation was t T=4h. The highest rhGH concentration was obtained as C rhGH=0.5gL(-1) with semi-defined medium-based feeding strategy designed with µ 0=0.25h(-1) using feed substrate stock solution containing 200gL(-1) glucose, 117gL(-1) (NH4)2HPO4, 100gL(-1) peptone, and 5mLL(-1) PTM1 at t=22h when the cell concentration reached to C X=8.29g L(-1). The overall product and cell yields on glucose were obtained as [Formula: see text]=7.21mgg(-1) and [Formula: see text]=0.12gg(-1), respectively. The results indicate the requirement of designing continuous feed stream in fed-batch production to enhance rhGH production by r-B. subtilis.