Anaerobic metabolism of propionate by polyphosphate-accumulating organisms in enhanced biological phosphorus removal systems
Anaerobic metabolism of propionate by polyphosphate-accumulating organisms in enhanced biological phosphorus removal systems
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DOI：
10.1002/bit.20480
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发表时间：
2005-07-05
影响因子：
3.8
通讯作者：
Keller, J
中科院分区：
文献类型：
--
作者：
Oehmen, A;Zeng, RJ;Keller, J
丙酸是一种碳底物，在许多首选物质中含量丰富，先前的几项研究表明，丙酸是一种比醋酸盐更适合于强化生物除磷(EBPR)的底物。研究了聚磷菌(PAOS)对丙酸酯的厌氧代谢。提出了一个代谢模型来描述PAO摄取丙酸的厌氧生化转化过程。该模型能够很好地预测以丙酸为唯一碳源的实验室规模反应器中PAO培养的实验数据。定量荧光原位杂交(FISH)分析表明，迄今为止唯一鉴定出的PAO是假丝酵母菌Acumulibacter phatis，占该培养物细菌总数的63%。聚乙酸乙酯的厌氧代谢主要产生聚β-羟基丁酸酯(PHB)，而以丙酸为碳源生产的聚β-羟基烷酸(PHA)的主要组分是聚β-羟基戊酸酯(PHV)和聚β-羟基-2-甲基戊酸酯(PH2 MV)。PHA的形成与乙酰辅酶A和丙酰辅酶A分子的选择性(或非随机)缩合很好地相关。结果表明，PAO对丙酸的最大比吸收速率为0.18C-mol/C-摩尔-生物量h，与文献报道的最大比醋酸盐吸收速率非常接近。通过PAO细胞膜输送1个碳摩尔的丙酸所需的能量也被确定为与1个碳摩尔的醋酸盐的输送相似。此外，实验结果表明，在碳摩尔的基础上，PAO对醋酸盐和丙酸的吸收具有类似的偏好。(C)2005年威利期刊公司。
Propionate, a carbon substrate abundant in many prefermenters, has been shown in several previous studies to be a more favorable substrate than acetate for enhanced biological phosphorus removal (EBPR). The anaerobic metabolism of propionate by polyphosphate accumulating organisms (PAOs) is studied in this paper. A metabolic model is proposed to characterize the anaerobic biochemical transformations of propionate uptake by PAOs. The model is demonstrated to predict very well the experimental data from a PAO culture enriched in a laboratory-scale reactor with propionate as the sole carbon source. Quantitative fluorescence in-situ hybridization (FISH) analysis shows that Candidatus Accumulibacter phosphatis, the only identified PAO to date, constitute 63% of the bacterial population in this culture. Unlike the anaerobic metabolism of acetate by PAOs, which induces mainly poly-beta-hydroxybutyrate (PHB) production, the major fractions of poly-beta-hydroxyalkanoate (PHA) produced with propionate as the carbon source are poly-beta-hydroxyvalerate (PHV) and poly-beta-hydroxy-2-methylvalerate (PH2MV). PHA formation correlates very well with a selective (or nonrandom) condensation of acetyl-CoA and propionyl-CoA molecules. The maximum specific propionate uptake rate by PAOs found in this study is 0.18 C-mol/C-mol-biomass h, which is very similar to the maximum specific acetate uptake rate reported in literature. The energy required for transporting 1 carbon-mole of propionate across the PAO cell membrane is also determined to be similar to the transportation of 1 carbon-mole of acetate. Furthermore, the experimental results suggest that PAOs possess a similar preference toward acetate and propionate uptake on a carbon-mole basis. (c) 2005 Wiley Periodicals, Inc.