Fig 3.

Expression of the sso1354 gene in E. coli. Cell extracts of BL21 E. coli cells transformed with pET28c-1354 after growth and IPTG induction were loaded on a nickel affinity chromatography spin column for the purification of the His-tagged protein. The protein fractions from all chromatographic steps were analyzed by SDS-PAGE followed by Coomassie staining: marker (M), membrane extract (lane 1), crude cytosolic extract (2), flowthrough (3), wash (4), and elution with 10, 50, 100, 250, and 500 mM imidazole (5, 6, 7, 8, and 9). An aliquot from the 250 mM imidazole elution step (lane 8) was analyzed on a zymographic gel (containing 0.1% CMC), and the cellulase activity band was revealed with Congo red after renaturation.