Biochemical characteristics and membrane fouling behaviors of soluble microbial products during the lifecycle of Escherichia coli
Biochemical characteristics and membrane fouling behaviors of soluble microbial products during the lifecycle of Escherichia coli
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大肠杆菌生命周期中可溶性微生物产物的生化特征和膜污染行为
DOI：
10.1016/j.watres.2021.116835
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发表时间：
2021
期刊：
影响因子：
12.8
通讯作者：
Fangang Meng
中科院分区：
文献类型：
--
作者：
Xiaofang Yang;Danyi Li;Zhong Yu;Yabing Meng;Xing Zheng;Shanshan Zhao;Fangang Meng
膜生物反应器中可溶性微生物产物（SMP）的生产过程和化学组成的复杂性在很大程度上限制了对膜污染的认识。在此，我们使用一个模型单菌株大肠杆菌更好地了解SMPs的化学性质和它们在膜污染中的作用。采用激发发射矩阵和平行因子分析（EEM-PARAFAC）、分子排阻色谱-有机碳检测（LC-OCD）和非靶向超高效液相色谱- Q-Exactive -MS（UPLC-Q-Exactive-MS）等先进技术，从化合物和分子水平研究了碳源和生长阶段对SMPs化学组成的影响。随后，在超滤（UF）过程中的膜污染倾向的作用进行了研究。结果表明，微生物的化学组成和结垢潜力与碳源和生长阶段有关。在指数生长期，主要由利用相关产物（UAP）和剩余底物组成。随着微生物进入稳定期和衰老期，不饱和脂肪酸和生物质相关产物（BAP）分别是主要成分。在葡萄糖培养基中产生的SMP含量高于在乙酸盐培养基中产生的SMP，并且在葡萄糖喂养的SMP中观察到更高丰度的腐殖荧光组分。UPLC-MS结果的货车Krevelen图显示，与葡萄糖喂养的SMP相比，在稳定期和衰老期，乙酸喂养的SMP含有更多的富含羧基的脂环族分子、肽样、芳香族和碳水化合物样组分。这些成分在不可逆膜污染中起着重要作用，如UF实验所示。标准堵塞和滤饼过滤分别是指数和稳定/衰老阶段收集的SMP过滤的主要结垢机制。我们的研究结果突出了SMP组合物和膜污染在化合物和分子水平之间的联系，并表明碳源和生长阶段强烈地决定了生产潜力，化学性质和污染行为的SMP。
The complexity of production process and chemical compositions of soluble microbial products (SMPs) largely limits the understanding of membrane fouling in membrane bioreactors (MBRs). Herein, we used a model single-strainEscherichia colito better understand the chemical natures of SMPs and their roles in membrane fouling. The effects of carbon source and growth phase on the chemical compositions of SMPs were identified at both the compound and molecular levels by using advanced techniques including excitation emission matrix and parallel factor analysis (EEM-PARAFAC), size exclusion chromatography coupled with organic carbon detection (LC-OCD), and untargeted ultra-performance liquid chromatography - Q-Exactive - mass spectrometry (UPLC-Q-Exactive-MS). Subsequently, the roles of SMPs in the propensity of membrane fouling during ultrafiltration (UF) were studied. The results showed that the chemical compositions and fouling potentials of SMPs were carbon source- and growth phase-dependent. In the exponential phase, SMPs mainly consisted of utilization-associated products (UAPs) and remaining substrates. As the microorganism progressed into the stationary and senescent phases, UAPs and biomass-associated products (BAPs) were the main components, respectively. The SMP contents generated in glucose medium were higher than those generated in acetate medium, and higher abundances of humic fluorescent components were observed in glucose-fed SMPs. Van Krevelen diagrams of the UPLC-MS results revealed that acetate-fed SMPs contained more carboxylic-rich alicyclic molecules, peptides-like, aromatic, and carbohydrates-like components than glucose-fed SMPs in the stationary and senescent phases. These components played a significant role in irreversible membrane fouling, as evidenced in UF experiments. Standard blocking and cake filtration were the main fouling mechanisms for the filtration of SMPs collected in the exponential and stationary/senescent phases, respectively. Our findings highlight linkages between SMP compositions and membrane fouling at both the compound and molecular levels and suggest that both the carbon source and growth phase strongly determine the production potential, chemical nature, and fouling behavior of SMPs.