Fe^(2+)和Fe^(3+)对大肠杆菌DH5α及其耐乙酸突变株生长及乙酸生成的影响

Effects of Ferrous and Ferric Ions on the Growth and Acetate Production of Escherichia coli DH5α and Its Acetate-Tolerant Mutant DA19

Fe^(2+)和Fe^(3+)对E.coliDH5α及其耐乙酸突变株DA19的代谢有较大影响。在以葡萄糖为碳源的基本培养基中,添加Fe^(2+)或Fe^(3+)后DH5α生长改善,菌体浓度增加,菌体得率(YX/G)提高,但同时产乙酸量也大为增加,且在添加Fe^(2+)后增加更多,然而其单位菌体的产乙酸量(YA/X)降低。DA19在添加Fe^(2+)或Fe^(3+)后生长改善,YX/G提高,同时产乙酸大大减少,YA/X和乙酸得率(YA/G)大大降低。DA19的生长还与Fe^(2+)的添加时间有关,在培养过程中添加Fe^(2+)越早,细胞浓度和YX/G增加的幅度越大,同时产乙酸、YA/X及YA/G下降的幅度也越大;在12h及其之后添加对DA19生长没有明显影响。DH5α和DA19在添加Fe^(2+)后生长改善的效果比Fe^(3+)明显。

Addition of ferric or ferrous ion in a medium with glucose as the sole carbon source greatly affected the metabolism of E. coli DH5α and its acetate-tolerant mutant DA19. The addition of ferric or ferrous ion also greatly improved the growth and cell yield based on consumed glucose （YX/G） of DH5α, and acetate production also greatly increased. Compared with addition of ferric ion, more acetate was produced, and the acetate yield based on biomass （YA/X） was lower when ferrous ion was added. For DA19,cell growth and YX/G increased, while acetate production, YA/X and YA/G decreased after the addition of ferric or ferrous ion. The metabolic behavior of DA19 was related to the time to add Fe^2＋. The earlier addition of Fe^2＋ , the greater the increase in cell concentration and YX/G, and the less the acetate formation, YA/X, and YA/G. Addition of Fe^2＋ later than 12 h had no apparent effect on DA19 culture. The effect of Fe^2＋ was more profound on the growth of DH5α and DA19 than that of Fe^3＋.