摘要
      在基于生物膜的废水处理系统中，系统pH对生物膜的生长和微生物的活性有着至关重要的影响。本研究研究了处理灰水的氧基膜生物膜反应器中pH依赖性污染物的去除、微生物生态位的演替和抗生素抗性基因（ARGs）的积累。结果表明，中性条件下生物膜浓度和活细胞最高，污染物去除率最高；生物膜中多种官能团使污染物得以吸附，有利于其连续生物去除。酸性条件下（pH=5.0）的微生物群落与其他条件下的微生物群落有显著差异（p<0.05）。中性和碱性生态位（pH=7.0和9.0）以有机物生物降解和氮还原细菌（如鞘氨醇杆菌目、假单胞菌属、黄杆菌属和苯杆菌属）为主，但在酸性条件下显著下降，导致反应器性能下降。生物膜中的ARGs（以korB、intI-1、sul1和sul2为主）远高于无细胞液体中的ARG，并且靶ARGs积累（korB、int I-1、blaCTX-M、qnrS）与生物膜连接的线性烷基苯磺酸钠（LAS）几乎呈线性正相关（R2>0.95，P<0.01）。LAS刺激功能微生物中ARGs的增殖（korB、sul-1和intI-1与相关微生物属显著相关），生物膜在ARGs传播中起着关键作用。在中性条件下，生物膜和出水中的ARGs相对较低，这表明pH控制可能是抑制ARGs在系统中传播和增殖的有效策略。
Abstract
System pH is found to crucially affect biofilm growth and microorganisms’ activity in the biofilm-based wastewater treatment system. This study investigated the pH-dependent pollutants removal, microbial niches succession and antibiotic resistance genes (ARGs) accumulation in an oxygen-based membrane biofilm reactor treating greywater. Results indicated that neutral conditions achieved the highest biofilm concentration and living cells, which enabled the highest pollutants removal rates; multifarious functional groups in biofilm enabled pollutants adsorption, which favored its continuous bio-removal. Microbial communities under acidic condition (pH = 5.0) were significantly different with that under other conditions (p < 0.05). The neutral and alkaline niches (pH = 7.0 and 9.0) were predominant by organics biodegradation and nitrogen reduction bacteria (e.g. Sphingobacteriales, Pseudomonas, Flavobacterium and Phenylobacterium), but which were significantly dropped under acidic conditions, leading to the declined reactor performance. ARGs in biofilm (predominant by korB, intI-1, sul1 and sul2) were much higher than that in the cell-free liquid and the target ARGs accumulation (korB, intI-1, blaCTX-M, qnrS) had nearly linear positive relationships (R2 > 0.95, P < 0.01) with biofilm-attached linear alkylbenzene sulfonate (LAS). LAS stimulate ARGs proliferation in functional microorganisms (korB, sul-1 and intI-1 were significantly associated with related microbial genus) and biofilm played a key role in ARGs dissemination. The relatively low ARGs in both biofilm and effluent under neutral conditions suggested that pH controlling can be an effective strategy to inhibit ARGs dissemination and proliferation in the system.

https://www.sciencedirect.com/science/article/abs/pii/S0013935122020527