Fig. 5

Combination of the effective engineering strategies and development of a fed-batch fermentation strategy. a Acarbose production profiles of SIPI12-34 and other mutants combined different genes overexpression were analyzed by HPLC. The table below illustrates the different combination strategies. Error bars show standard deviations. b Schematic diagram of genetic engineering for obtaining SIPI2207. GS represents the gene encodes glycogen synthase. c Acarbose production of SIPI2207 with addition of different sugars during the fermentation process. Control represents no supplementation for SIPI2207. Glucose represents supplementation of 20 g/L glucose for SIPI2207 at 48 h. Maltose represents supplementation of 20 g/L maltose for SIPI2207 at 48 h. Glucose + Maltose represents supplementation of a 10 g/L mixture of glucose and maltose for SIPI2207 at 48 h. d Detection of acarbose production of SIPI2207 and SIPI12-34 with addition of different amounts of glucose at different culture time