The scale-up of fermentation process plays an important role in the industrialization of lab results.As the increase of fermentation scale

the microenvironment of microorganism would be different

which would result in the change of microorganism metabolism and affect the results of scale-up.In order to accomplish the industrialization of HT-1 production

high-expression of HT-1 fusion protein was carried out with fed-batch culture method of E.coli in a 200 L fermentor.The problem of the decrease in HT-1 fusion protein expression level caused by secondary seed culture process was solved by the methods of advancing initial induction and increasing inoculation volume.As a result

the cell density

the expression level

the cell yield as well as the volume yield of HT-1 fusion protein were achieved to 55.1 g·L-1

27.4%

0.056 g·(g cell)-1 and 3.103 g·L-1

respectively.Compared with the results before optimization

these indexes were increased by 9.8%

23.4%

14.3% and 25.2%

respectively.These results provide an important reference for the optimization and scale-up of HT-1 production.