Phenotype characterization
Cell samples from cultures in duplicate or triplicate shake flasks were
collected at various time points throughout the fermentation. Dry cell
weight (DCW) in 3 mL culture was measured after filtration for
monitoring cell growth. The concentration of residual glucose in culture
was determined by salicylic acid method (Zou, Hang, Chu, Zhuang, &
Zhang, 2009b). The erythromycin titer was measured by the modiļ¬ed
colorimetric method (Zou et al., 2009a).