Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam, 603 102, Tamil Nadu, India.
Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam, 603 102, Tamil Nadu, India; Homi Bhabha National Institute, BARC Training School Complex, Anushakti Nagar, Trombay, Mumbai, 400 094, India.
Chemosphere. 2022 Nov;307(Pt 4):136103. doi: 10.1016/j.chemosphere.2022.136103. Epub 2022 Aug 19.
Formation of aerobic granular sludge (AGS), process performance and microbial community structure were investigated in lab-scale sequencing batch reactors (SBR) operated without and with oxytetracycline (OTC). Granulation of activated sludge and appearance of AGS was observed in parallel SBRs operated without and with OTC. However, formation of well-settling aerobic granules was relatively faster in the SBR fed with 100 μg/L OTC and observed within 2 weeks of start-up. Ammonium, total nitrogen, and phosphorus removals were quickly established in the AGS cultivated without OTC. In contrast, nitrogen and phosphorus removals were lower in the OTC fed SBR. But, a gradual improvement in nitrogen and phosphorus removals was observed. After 45 days, nitrogen and phosphorous removals were stabilized at 99% and 70%, respectively, due to establishment of OTC-tolerant community. qPCR revealed the impact of OTC on ammonium oxidizing bacteria, polyphosphate accumulating organisms and their enrichment during exposure to OTC. Ammonium and phosphorus were majorly removed via nitritation-denitritation and enhanced biological phosphorus removal (EBPR) pathways, respectively, in the presence of OTC. Brevundimonas (35%), Thaurea (14%) sp. Ca. Competibacter (5.6%), and Ca. Accumulibacter (4.2%) were enriched in OTC-fed AGS. Of the two OTC-tolerant strains isolated, Micrococcus luteus exhibited growth and efficient OTC biotransformation at different OTC concentrations. Moreover, M. luteus was predominantly growing in the form of aggregates. Key traits such as tolerance, biotransformation and high autoaggregation ability allowed a niche for this strain in the granules. This work has important implications in understanding the effect of antibiotics on AGS and designing AGS based treatment for antibiotic-laden wastewaters.
在没有和有土霉素（OTC）的情况下，在实验室规模的序批式反应器（SBR）中研究了好氧颗粒污泥（AGS）的形成、工艺性能和微生物群落结构。在没有和有 OTC 的平行 SBR 中观察到活性污泥的颗粒化和 AGS 的出现。然而，在含有 100μg/L OTC 的 SBR 中，AGS 的形成相对较快，在启动后 2 周内即可观察到。在没有 OTC 的 AGS 中，氨氮、总氮和磷的去除迅速建立。相比之下，在 OTC 进料的 SBR 中氮和磷的去除率较低。但是，氮和磷的去除率逐渐提高。45 天后，由于建立了耐 OTC 的群落，氮和磷的去除率分别稳定在 99%和 70%。qPCR 揭示了 OTC 对氨氧化菌、聚磷菌及其在暴露于 OTC 时的富集的影响。在存在 OTC 的情况下，氨和磷主要通过硝化-反硝化和增强的生物除磷（EBPR）途径去除。Brevundimonas（35%）、Thaurea（14%）sp. Ca.Competibacter（5.6%）和 Ca.Accumulibacter（4.2%）在 OTC 喂养的 AGS 中富集。从两种耐 OTC 的菌株中分离出的一株是微球菌，它在不同的 OTC 浓度下表现出生长和有效的 OTC 生物转化。此外，M. luteus 主要以聚集的形式生长。该菌株的耐受力、生物转化和高自动聚集能力等关键特性为其在颗粒中的生长提供了一个小生境。这项工作对于理解抗生素对 AGS 的影响以及设计基于 AGS 的处理抗生素废水具有重要意义。
