Wong Man-Tak, Liu Wen-Tso
Division of Environmental Science and Engineering, National University of Singapore, Singapore 117576.
Environ Microbiol. 2007 Jun;9(6):1485-96. doi: 10.1111/j.1462-2920.2007.01267.x.
A group of uncultured tetrad-forming organisms (TFOs) was enriched in an acetate-fed anaerobic-aerobic sequencing membrane bioreactor showing deteriorated enhanced biological phosphorus removal capacity. Based on 16S rRNA gene clone library and fluorescence in situ hybridization (FISH) analyses, these TFOs were identified as novel members of the Defluviicoccus cluster in the Alphaproteobacteria, accounting for 90 +/- 5% of the EUBmix FISH-detectable bacterial cell area in the reactor biomass. Microautoradiography in combination with FISH and polyhydroxyalkanoate (PHA) staining revealed that these Defluviicoccus-related TFOs could take up and transform acetate, lactate, propionate and pyruvate, but not aspartic acid and glucose, into PHA under anaerobic conditions. In contrast, under continuous anaerobic-aerobic cultivation, Defluviicoccus vanus, the only cultured strain from the cluster, was able to take up glucose with concurrent glycogen consumption and PHA production under anaerobic conditions. Under subsequent aerobic conditions, the accumulated PHA was utilized and the biomass glycogen levels were restored. These findings not only re-confirmed these Defluviicoccus-related TFOs as glycogen-accumulating organisms, but also revealed unexpected levels of physiological, phylogenetic and morphological diversity among members of the Defluviicoccus cluster.
在一个以乙酸盐为进料的厌氧-好氧序批式膜生物反应器中，一组未培养的四联形成菌（TFOs）得到富集，该反应器的强化生物除磷能力出现恶化。基于16S rRNA基因克隆文库和荧光原位杂交（FISH）分析，这些TFOs被鉴定为变形菌门中Defluviicoccus簇的新成员，占反应器生物质中EUBmix FISH可检测细菌细胞面积的90±5%。微放射自显影结合FISH和聚羟基脂肪酸酯（PHA）染色显示，这些与Defluviicoccus相关的TFOs在厌氧条件下可摄取并将乙酸盐、乳酸盐、丙酸盐和丙酮酸盐转化为PHA，但不能将天冬氨酸和葡萄糖转化为PHA。相比之下，在连续厌氧-好氧培养条件下，该簇中唯一的培养菌株瓦氏Defluviicoccus在厌氧条件下能够摄取葡萄糖，同时消耗糖原并产生PHA。在随后的好氧条件下，积累的PHA被利用，生物质糖原水平得以恢复。这些发现不仅再次证实这些与Defluviicoccus相关的TFOs为糖原积累菌，还揭示了Defluviicoccus簇成员之间意想不到的生理、系统发育和形态多样性水平。
