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Jianan Sun,Liaoyuan Zhang,Ben Rao,Yunbin Han,Ju Chu,Jiawen Zhu,Yaling Shen,Dong-Zhi Wei 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.3
Enhanced acetoin production was carried out by Serratia marcescens H32. First, medium compositions were optimized statistically for shake flask fermentations to produce acetoin. Sucrose and corn steep liquor powder (CSLP) were identified as the most significant factors by Plackett–Burman design. The path of steepest ascent and response surface methodology were then employed to determine the optimal concentrations of the two factors. Acetoin yield was up to 41.5 g/L in flask fermentations using the optimized medium. Furthermore, the optimal medium was used to conduct fermentation experiments in a 3.7-L bioreactor. The influences of different agitation speeds on acetoin production were investigated. Based on a process analysis, a two-stage agitation speed control strategy was proposed, in which the agitation speed was controlled at 700 rpm during the first 8 h and then switched to 600 rpm. A relatively high acetoin concentration (44.9 g/L)and high acetoin productivity (1.73 g/L/h) were achieved by applying this strategy. Fed-batch fermentation based on the two-stage agitation speed control strategy was performed,and a maximum acetoin concentration of 60.5 g/L with productivity of 1.44 g/L/h was achieved. Enhanced acetoin production was carried out by Serratia marcescens H32. First, medium compositions were optimized statistically for shake flask fermentations to produce acetoin. Sucrose and corn steep liquor powder (CSLP) were identified as the most significant factors by Plackett–Burman design. The path of steepest ascent and response surface methodology were then employed to determine the optimal concentrations of the two factors. Acetoin yield was up to 41.5 g/L in flask fermentations using the optimized medium. Furthermore, the optimal medium was used to conduct fermentation experiments in a 3.7-L bioreactor. The influences of different agitation speeds on acetoin production were investigated. Based on a process analysis, a two-stage agitation speed control strategy was proposed, in which the agitation speed was controlled at 700 rpm during the first 8 h and then switched to 600 rpm. A relatively high acetoin concentration (44.9 g/L)and high acetoin productivity (1.73 g/L/h) were achieved by applying this strategy. Fed-batch fermentation based on the two-stage agitation speed control strategy was performed,and a maximum acetoin concentration of 60.5 g/L with productivity of 1.44 g/L/h was achieved.
Rao Ben,Fan Jiying,Sun Jian’an,Truong Ngoc Tu,Sun Jing,Zhou Jingsong,Qiuyi,Shen Yaling 한국생물공학회 2016 Biotechnology and Bioprocess Engineering Vol.21 No.1
An artificial network which can accomplish recombinant protein synthesis guided by cell population in E. coli was constructed. The successful functioning of this network requires two plasmids, pWNB and pET. pWNB is responsible for production of T7 RNA polymerase, which controls pET; pET, in turn, regulates the production of target proteins. Several model proteins were tested and the results show that this E. coli system can be used to efficiently express various recombinant proteins. Since system contains T7 RNA polymerase production elements, it is transferable and applicable to well-characterized E. coli strains. Compared to the IPTG-induced system, an equal or greater amount of target protein can be obtained using this auto-inducible expression system in flasks and bioreactors. Our results suggest that it is a competitive alternative to other expression systems used in labs or for industrial applications.