摘要：The effects of the addition of various surfactants on the cell growth and production of vitamin K2 metabolites, such as intracellular menaquinone-4 (MK-4), extracellular MK-4, intracellular MK-6 and extracellular MK-6, were studied in the submerged culture of Escherichia sp. All of the added surfactants caused the extension of the exponential phase. Betaine, polyoxyethylene oleyl ether and Tween-80 were favourable to the cell growth of Escherichia sp. mutant strain FM3-1709. The highest cell growth (Xmax), biomass production rate (Qx) and biomass yield (Yx/s) were (12.6±0.2) g/L, (0.21±0.01) g/(L·h) and (2.42± 0.02) g/g, respectively. The results show that the addition of all surfactants led to a lower production of intracellular MK-4, whereas the production of extracellular MK-4 increased remarkably. Among the five investigated surfactants, the addition of the nonionic surfactant polyoxyethylene oleyl ether (1.0 g/L) led to the highest production of extracellular MK-4 ((33.6±0.4) mg/L), MK-6 ((2.56±0.07) mg/L) and the highest yield of total MK-4 ((47.6±0.4) mg/L) and MK-6 ((6.0±0.1) mg/L). The addition of polyoxyethylene oleyl ether proved to be more beneficial for the secretion of MK-4 than MK-6.
