College of Environment and Ecology, Chongqing University, Chongqing, People's Republic of China.
National Base of International Science and Technology Cooperation for Intelligent Manufacturing Service, Chongqing Key Laboratory of Catalysis & New Environmental Materials, Chongqing Technology and Business University, Chongqing, People's Republic of China.
Environ Technol. 2022 Aug;43(19):2909-2921. doi: 10.1080/09593330.2021.1909658. Epub 2021 Apr 5.
Different microbial aggregates show substantial differences in morphology, and extracellular polymer substances have been confirmed to play a key role in the formation of aggregates. In this study, three different microbial aggregates and their exopolysaccharides were compared. The results show that the granular sludge was largest in size and the most compact in shape. Biofilms with a certain thickness had the next greatest density, and flocculent sludge, with the smallest particle size, was the loosest. The extended Derjaguin-Landau-Verwey-Overbeek analysis shows that hydrogen bonding, hydrophobic and electrostatic interactions affect the aggregation of microorganisms. A comparison of exopolysaccharides shows that granular sludge exopolysaccharides show the highest hydrophobicity (38.08%) and lowest surface charge (-20.5 mV), followed by biofilm exopolysaccharides (27.9% and -24.8 mV respectively). The results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy show that the contents of hydrophilic and hydrophobic functional groups and charged functional groups of exopolysaccharides affect the above properties of exopolysaccharides, thereby affecting microbial aggregation. In addition, the hydrogen bond content of exopolysaccharides in granular sludge (19.3%), biofilm (19.2%) and activated sludge (18.9%) decreased sequentially. This also affects the cross-linking of microbial exopolysaccharides to form hydrogels. Finally, the results of confocal laser scanning microscopy showed that, different from the other two aggregates, the extracellular α-polysaccharides of granular sludge are mainly distributed in the nucleus, which is more conducive to aggregation. The research results of this thesis provide a new understanding of the differences in the aggregation morphology of different aggregates from the perspective of exopolysaccharides.
不同的微生物聚集体在形态上存在显著差异，已证实细胞外聚合物在聚集体的形成中起着关键作用。在这项研究中，比较了三种不同的微生物聚集体及其胞外多糖。结果表明，颗粒污泥的粒径最大，形态最紧密。具有一定厚度的生物膜次之，密度较大，而粒径最小的絮状污泥最疏松。扩展的德加古因-兰德劳-韦尔韦尔克分析表明，氢键、疏水和静电相互作用影响微生物的聚集。对胞外多糖的比较表明，颗粒污泥胞外多糖表现出最高的疏水性（38.08%）和最低的表面电荷（-20.5 mV），其次是生物膜胞外多糖（分别为 27.9%和-24.8 mV）。傅里叶变换红外光谱和 X 射线光电子能谱的结果表明，胞外多糖中亲水性和疏水性官能团以及带电官能团的含量影响胞外多糖的上述性质，从而影响微生物的聚集。此外，颗粒污泥（19.3%）、生物膜（19.2%）和活性污泥（18.9%）中胞外多糖的氢键含量依次降低。这也影响了微生物胞外多糖的交联形成水凝胶。最后，共聚焦激光扫描显微镜的结果表明，与其他两种聚集体不同，颗粒污泥的胞外α-多糖主要分布在核内，这更有利于聚集。本论文的研究结果从胞外多糖的角度为理解不同聚集体聚集形态的差异提供了新的认识。
