MUCT脱氮除磷系统中聚磷菌(Candidatus Accumulibacter)和氨氧化细菌(AOB)的菌群结构及组成特征

Community structure and the population characteristics of “Candidatus Accumulibacter” and ammonia-oxidizing bacteria in a MUCT process

采用MUCT(Modified University of Cape Town)工艺处理低C/N实际生活污水,通过控制溶解氧和缩短水力停留时间(HRT)等手段实现短程硝化,并在短程硝化的基础上取得了良好的反硝化除磷效果。分别采用功能基因ppk1和amo A作为遗传标记对MUCT工艺短程阶段的聚磷菌(Candidatus Accumulibacter)和氨氧化细菌(AOB)的菌群结构进行了研究。ppk1功能基因系统发育分析结果表明,MUCT工艺中Candidatus Accumulibacter分支具有多样化,共包含IID、IIC、IIF 3个进化枝。Candidatus Accumulibacter以TypeⅡ型为主,其中分支Acc-IID占克隆文库的94.3%,是Candidatus Accumulibacter中的优势菌属。证实了在以亚硝酸盐为电子受体的条件下,Acc-IID为除磷的主要承担者。分支Acc-IIF的出现可能与反应系统保持较高温度有关。amo A基因的系统发育分析结果表明,所有AOB序列属于Nitrosomonas europaea lineage。通过低溶解氧和短HRT建立的短程是N.europaea lineage成为AOB中优势菌属的重要原因。研究表明,短程反硝化条件下MUCT反应器中的优势Candidatus Accumulibacter和AOB分别为IID和N.europaea lineage,其丰度和菌群结构是影响污水生物除磷和硝化效果的主要因素。

The paper is aimed at presenting its investigation of the community structures and the influential factors of ＂Candidatus Accumulibacter＂ and ammonia-oxidizing bacteria （AOB） under the condition of nitritation in which domestic wastewater with a low C/N ratio is treated via Modified University of Cape Town （MUCT） process lasting for 167 days under the low dissolved oxygen mass concentration of 0. 5 mg/L. Furthermore, the paper has also realized the nitritation and denitrifying phosphorus （P） removal for a short hydraulic retention time of 6 h operated for 68 days. The results of its investigation and experiments show that P removal has been mainly accomplished by denitrification, about 90% of which has been done in the anoxic zone, with P removal efficiency clearly correlated with the nitrite accumulation rate. In addition, our experience shows that it is possible to use polyphosphate kinase 1 gene （ppkl） and amoA gene as the phylogenetic markers for the investigation of the community structures and population dynamics of Candidatus Accumulibacter and AOB, respectively, in MUCT process. What＇s more important, the phylogenetic analysis of Candidattts Accumulibacter proves that Acc- IID of Type II turns to be the dominant species and accounts for 94. 3% of ppkl gene clone library. Furthermore, it has been made possible to enrich Acc-IID clade by using nitrite as the electron acceptor extensively at the high nitrite accumulation rate, for in so doing, it would be possible to lead to the stable performance of denitrifying P removal. While Acc-IIC and Aec-IIF can also be found at a rate of 1.9% and 3.8% of ppk1 gene clone library respectively, and the finding of Aec-IIF may be in close correlation with the high temperature of MUCT process. At the same time, the phylogenetic analysis of AOB amoA gene suggests that all the sequences can be attributed to Nitrosomonas europaea lineage, whereas nitritation established through low dissolved oxygen concentration may account for the dominant species N. europaea cluster of AOB. Thus, it can be concluded that the outcome of our experiments can indicate that the dominant Candidatus Aecumulibacter and AOB in MUCT process are lid and Nitrosomonas europaea lineage, respectively. The abundance and the community configuration of liD and Nitrosomonas europaea lineage can be expected to have remarkable effects on the performance of the biological nitrogen and phosphorus removal.