低聚磷酸盐对粪产碱杆菌合成热凝胶的影响

粪产碱杆菌合成热凝胶需要消耗大量ATP用于前体物质UDPG的再生,利用3种具有不同高能磷酸键的低聚磷酸盐Na4P2O7(2P)、Na5P3O10(3P)和(NaPO3)6(6P)作为高能磷酸键供体,并取代培养基中的KH2PO4-K2HPO4(1P)而作为磷元素供体,研究其对粪产碱杆菌合成热凝胶的影响。结果表明相对于对照磷元素摩尔含量的单倍和双倍量添加3P和6P能够分别提高热凝胶产量23%和134%,达到15.1g/L和30.0g/L;同时副产物乙酸分别较对照降低了87.5%和77.7%;在以双倍量添加6P后,副产物甲酸的生成也显著降低75.7%。当培养基中不含碳酸钙进行低聚磷酸盐添加实验时,生物量显著降低,热凝胶合成几乎没有,发酵液pH最低降到2.1。以磷元素单倍量和双倍量分别添加3P和6P,并与1P混合发酵时,热凝胶产量变化不大;但是,当发酵液不存在碳酸钙而1P被作为缓冲物质时,以单倍量和双倍量添加6P使得热凝胶产量较对照分别提高60.4%和49.4%,分别达到18.4g/L和16.9g/L。

Influence of Low-polyphosphates on Curdlan Production by Alcaligenes faecalis var. myxogene

A large amount of ATP is consumed to regenerate precursor UDPG for curdlan biosynthesis in Alcaligenes faecalis var. myxogens. In this study, low-polyphosphates with high-energy phosphate bond of Na4P2O7 (2P), Na5P3O10 (3P) and (NaPO3)6 (6P) were employed as high-energy phosphate bond and phosphate donor to substitute KH2PO4-K2HPO4 (1P) in medium for curdlan production by Alcaligenes faecalis var. myxogene. Results showed that curdlan production was enhanced 23% and 134% than that of control respectively, which reached 15.1 g/L and 30.0 g/L, when one-fold and two-fold high concentration of phosphate from 3P and 6P were added in the medium. Meanwhile, byproducts of acetic acid were decreased 87.5% and 77.7% respectively. Formic acid was also decreased 75.7% when two-fold 6P were added in the medium. However, when CaCO3 was removed in the medium, pH and biomass were decreased remarkably, therefore, little or no curdlan was produced when these low-polyphosphates were added in medium. When 3P and 6P were separately mixed with 1P at the amount of one-fold and two-fold high concentration of phosphate for fermentation, there was no change on curdlan production. Nevertheless, if 1P was used as buffer substance and without CaCO3 in the medium, curdlan production could be enhanced to 60.4% and 49.4% than that of the control when 6P was added at the amount of one-fold and two-fold high concentration, reached to 18.4 g/L and 16.9 g/L.