An assessment of seed quality on erythromycin production by recombinant strain Saccharopolyspora erythraea ZL1004 was investigated in 151 fermenter. Adding 10 g/l corn steep liquor and 30 g/l soybean flour in seed medium were beneficial to improve cell growth, and the maximal biomass reached 36% at 40 h. Enzyme activity in cell showed that the maximal protease and minimum amylase were appeared in this stage. Compared with the control in 501 fermenter, the cell metabolism with inoculation of the optimized seed cultivation was obviously quicker, and physiological response such as oxygen uptake rate (OUR) and carbon dioxide evolution rate (CER) were also improved. The maximal erythromycin A production was 9160 U/ml at 215 h, which was increased by 21.63% with respect to the control. It was the first report to integrate cell growth characteristics and physiological response method to assess the seed quality for erythromycin production. (C) 2010 Elsevier Ltd. All rights reserved.