Abstract: Two expression vectors, pET-15bcrtEIB in which crtE, crtB, crtI of Erwinia uredovora were cloned and pACYC-184crtY in which crtY was cloned, were transformed into E.coli BL21(DE3) simultaneously to construct engineering bacterium. The engineering bacterium could accumulate β-carotene when induced by IPTG. Effects of different culture conditions such as carbon sources, nitrogen sources, metal ions, culture temperature, light, medium pH and induction time on bacterial growth and β-carotene accumulation were investigated. The optimal culturing conditions obtained are as follows: Modified LB broth (trypton 10 g/L, yeast extract 10 g/L, soluble starch 5 g/L, MgCl2 0.04 g/L, FeCl3 0.01 g/L and NaCl 10 g/L as well as pH 5.8) as medium and in light, the engineering bacterium firstly is shake-cultured at 37 ℃ to OD600 0.6 of culture liquid, subsequently IPTG added to final concentration 0.5 mmol/L, and then further cultured for 14 h at 28 ℃. The engineering bacterium could grow to 7.32 g dw/ L in LB medium and accumulate β-carotene to 5.11 mg/g dw under optimal culture conditions.

Key words: &beta, -carotene； engineering bacterium； culture conditions