Fig. 2

Analysis of rHtA expression under fermentation conditions. a Time course of changes in wet-cell weight in a 5-l bioreactor. Cells were collected at the indicated times. The wet weight of cultured cells was obtained by centrifugation at 16000g for 15 min at 4 °C. b SDS-PAGE analysis of the time course associated with rHtA expression in the 5-l bioreactor. Culture supernatant was collected at the indicated times after methanol induction. Protein concentration in the supernatant was determined by Bradford assay, and BSA was used as the standard. c Detection of rHtA concentration by gel scanning. Culture supernatant was collected at the indicated times after methanol induction. The supernatants were precipitated, then analyzed on 15% SDS-PAGE and stained with Coomassie blue R250. After the decolorization, the protein imaging system scanned the SDS-PAGE gel. The gray scale of the protein strip was analyzed by Quantity One software (Bio-Rad) and the concentrations of target bands were calculated