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. 2006 Aug;72(8):5283–5288. doi: 10.1128/AEM.00808-06

FIG. 4.

FIG. 4.

Effects of enhanced expression of ssgA on growth and tyrosinase production of S. lividans. (A) Tyrosinase production by S. lividans. S. lividans 1326 containing pIJ703 was transformed with pGWS4-SD (ssgA overproduction; strain GSAL1) or with pSET152 (control plasmid; strain 1326), and transformants were selected on R2YE agar plates. Representative plates with around 500 colonies are shown. Note the strongly enhanced tyrosinase production by the SsgA-overproducing transformant. As follows from the data in panel B, the SsgA-overproducing strain produced two to three times more tyrosinase than the control strain. Hence, enhanced expression of ssgA resulted in an important improvement of the tyrosinase yield. (B) Batch fermentation of SsgA-overproducing S. lividans GSAL1/pIJ703 and its parent, 1326/pIJ703 (harboring control plasmid pSET152), was performed in 4 liters of TSBS in a 5-liter fermentor. The pH was maintained at 6.7, and the dissolved oxygen concentration was maintained at 80%. Biomass accumulation of S. lividans 1326 (▴) and GSAL1 (•) was calculated from dry weight measurements. Tyrosinase production (for description of the assay, see Materials and Methods) is represented by the open symbols.