Recombinant E. coli BL 21 was cultivated in high cell density to produce human-like collagen. The effects of the feeding of nitrogen source, controlled by an auto on/off-feeding mode with two different cycles of 0.5 min and 4 rain intervals, oxygen-enrichment methods and inducement strength on the cell yield and human-like collagen production were investigated. The studies showed that nitrogen source feeding in fast cycle could result in higher human-like collagen production than that in slow cycle; and the feedback regulation of glucose, increase of the pressure of fermentation bioreactor, and supply of oxygen-enriched air could all increase cell yield and human-like collagen production. The effects of inducement strength on protein expression were found important. When OD600 reached 90—100, the cultivation temperature was increased to 42℃ to begin induction for 2—3 h, and then shifted to 39℃ for 5—6 h induction, the cell density and human-like collagen production could reach 96 g·L^-1 [DCW (dry cell mass)] and 19.8% (g·g^-1 DCW) respectively.
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