Enhanced curdlan production in Agrobacterium sp. ATCC 31749 by addition of low-polyphosphates
Enhanced curdlan production in Agrobacterium sp. ATCC 31749 by addition of low-polyphosphates
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DOI：
10.1007/s12257-010-0145-5
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发表时间：
2011-04
影响因子：
3.2
通讯作者：
Lijun Yu;Jianrong Wu;Jia Liu;X. Zhan;Z. Zheng;C. Lin
中科院分区：
文献类型：
--
作者：
Lijun Yu;Jianrong Wu;Jia Liu;X. Zhan;Z. Zheng;C. Lin
A large amount of adenosine triphosphate with high energy phosphate bonds is required for uridine triphosphate regeneration during curdlan biosynthesis byAgrobacteriumsp. ATCC 31749. To supply high energy for curdlan synthesis, three low-polyphosphates (Na4P2O7, Na5P3O10, and (NaPO3)6) with higher energy phosphate bonds were employed to substitute for KH2PO4-K2HPO4in fermentation medium. Two genes encoding the polyphosphate metabolizing enzymes, polyphosphate kinase and exopolyphosphatase, were amplified and showed 95% homology to those inAgrobacteriumsp. C58 by sequence analysis. The curdlan yields were enhanced by 23 and 134% when phosphate concentrations 0.024 mol/L of Na5P3O10and 0.048 mol/L of (NaPO3)6respectively, were added in the medium. The maximum curdlan yield of 30 ± 1.02 g/L was obtained with the addition of 0.048 mol/L of (NaPO3)6with 5 g/L CaCO3in the medium. When CaCO3was removed from the culture and the three lowpolyphosphates were added, the pH and biomass yield dropped remarkably and little or no curdlan was produced. The culture containing 0.048 mol/L of (NaPO3)6was mixed with KH2PO4-K2HPO4and CaCO3in the medium, but showed no effect on curdlan production. However, curdlan yield was improved by 49 ∼ 60% when CaCO3was removed from the medium and KH2PO4-K2HPO4acted as a buffer. It appears that the positive effect of (NaPO3)6on curdlan production required the buffering capacity of CaCO3and the absence of KH2PO4-K2HPO4competing as a phosphate supplier.
