Advanced Water Management Centre, The University of Queensland, St. Lucia, QLD, Australia.
Appl Microbiol Biotechnol. 2011 Dec;92(6):1297-305. doi: 10.1007/s00253-011-3385-1. Epub 2011 Jun 14.
A gel-forming exopolysaccharide was previously shown to play an important structural role in aerobic granules treating nutrient-rich industrial wastewater. To identify whether this exopolysaccharide performs a similar role in other granular biomass and if conditions favouring its production can be more precisely elucidated, extracellular polymeric substances (EPS) were extracted from granules grown under four different operating conditions. (1)H nuclear magnetic resonance (NMR) spectroscopy of their EPS indicated that the gel-forming exopolysaccharide was expressed in two granular sludges both enriched in Candidatus "Competibacter phosphatis". In contrast, it was not expressed in granules performing denitrification with methanol as a carbon source and nitrate as the electron acceptor or granules enriched in Candidatus "Accumulibacter phosphatis" performing enhanced biological phosphorus removal from synthetic wastewater. In one of the first two sludges, the exopolysaccharide contained in the seeding granular sludge continued to be a major component of the granule EPS while Competibacter was being enriched. In the second sludge, a floccular sludge not containing the gel-forming exopolysaccharide initially was also enriched for Competibacter. In this sludge, an increase in particle size was detected coinciding with a yield increase of EPS. NMR spectroscopy confirmed its yield increase to be attributable to the production of this structural gel-forming exopolysaccharide. The results show that (1) the particular gel-forming exopolysaccharide previously identified is not necessarily a key structural exopolysaccharide for all granule types, and (2) synthesis of this exopolysaccharide is induced under conditions favouring the selective enrichment of Competibacter. This indicates that Competibacter may be involved in its production.
先前的研究表明，一种形成凝胶的胞外多糖在好氧颗粒处理富含营养的工业废水中起着重要的结构作用。为了确定这种胞外多糖是否在其他颗粒生物量中发挥类似作用，以及是否可以更准确地阐明有利于其产生的条件，从在四种不同操作条件下生长的颗粒中提取了细胞外聚合物物质（EPS）。对其 EPS 的 1H 核磁共振（NMR）光谱分析表明，在两种富含 Candidatus "Competibacter phosphatis"的颗粒污泥中表达了形成凝胶的胞外多糖。相比之下，在以甲醇为碳源和硝酸盐为电子受体进行反硝化的颗粒中，或在富含 Candidatus "Accumulibacter phosphatis"并从合成废水中进行强化生物除磷的颗粒中，均未表达该多糖。在前两个污泥中的一个中，在接种颗粒污泥中包含的胞外多糖继续成为颗粒 EPS 的主要成分，而 Competibacter 被富集。在第二个污泥中，最初不含有形成凝胶的胞外多糖的絮状污泥也被富集了 Competibacter。在该污泥中，检测到粒径增加，同时 EPS 的产量也增加。NMR 光谱证实，其产量增加归因于这种结构形成凝胶的胞外多糖的产生。结果表明，（1）先前鉴定的特定形成凝胶的胞外多糖不一定是所有颗粒类型的关键结构胞外多糖，（2）这种胞外多糖的合成是在有利于 Competibacter 选择性富集的条件下诱导的。这表明 Competibacter 可能参与了其产生。
