Composition of EPS fractions from suspended sludge and biofilm and their roles in microbial cell aggregation

Effects of CeO2 nanoparticles on production and physicochemical characteristics of extracellular polymeric substances in biofilms in sequencing batch biofilm reactor

“…Slight shifts were observed for the peak locations of the EPS (LB-EPS and TB-EPS) at various CeO 2 NP concentrations. This shift was also reported by Sheng and Yu (2006) and Zhang et al (2014), and revealed the changes in the conformations of the EPS components at different CeO 2 NP concentrations.…”

“…In addition, Peak C in the TB-EPS spectrum suddenly vanished when the concentration of CeO 2 NPs reached 50 mg/L, whereas its intensity increased in the LB-EPS. Such differences demonstrated that adding CeO 2 NPs led to different compositions and amounts of EPS fraction production (Zhang et al, 2014). Both Peaks D and E correspond to protein-like substances, and the presence of these indicates that the EPS contained more abundant protein species at high CeO 2 NP concentrations, also in accordance with an increased PRO content (Table 1) (Chen et al, 2003;Sheng et al, 2013).…”

“…Three main peaks (A, B, C) (Fig. 2) were observed from the fluorescence spectra of the LB-EPS and TB-EPS, both with and without the presence of CeO 2 NPs, and were identified according to literature (Zhang et al, 2014;Sheng and Yu, 2006;Chen et al, 2003). The fluorescence peak positions and fluorescence intensity of the different EPS fractions in the 3D-EEM spectra are detailed in Table S1.…”

“…The flocculating efficiency of EPS in biofilms varied relative to the changing trend of the zeta potential (Zhang et al, 2014). The zeta potentials of different EPS fractions were investigated using a Zetasizer Nano ZS90 (Malvern Instruments, UK).…”

“…The TB-EPS, which have a particular shape, are present in the inner layer of the biofilm, while the LB-EPS are in the outer layer, and are loose, without a distinct boundary (Sheng et al, 2010). It is reasonable to assume that EPS containing various fractions of TB-EPS and LB-EPS exhibit different physicochemical properties in protecting the bacteria from the hostile external environmental conditions (Zhang et al, 2014). Furthermore, the different compositions, with the various characteristics of each of the EPS fractions in terms of organic matter and cations, possess a diverse flocculability in their underlying bioflocculants (Yu et al, 2009).…”