Physicochemical Properties of Extracellular Polymeric Substances Produced by Three Bacterial Isolates From Biofouled Reverse Osmosis Membranes

Abstract

This work describes the chemical composition of extracellular polymeric substances (EPS) produced by three bacteria (RO1, RO2, and RO3) isolated from a biofouled reverse osmosis (RO) membrane. We isolated pure cultures of three bacterial strains from a 7-year-old biofouled RO module that was used in a full-scale seawater treatment plant. All the bacterial strains showed similar growth rates, biofilm formation, and produced similar quantities of proteins and polysaccharides. The gel permeation chromatography showed that the EPS produced by all the strains has a high molecular weight; however, the EPS produced by strains RO1 and RO3 showed the highest molecular weight. Fourier Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance (1H NMR), and Carbon NMR (13C NMR) were used for a detailed characterization of the EPS. These physicochemical analyses allowed us to identify features of EPS that are important for biofilm formation. FTIR analysis indicated the presence of α-1,4 glycosidic linkages (920 cm–1) and amide II (1,550 cm–1) in the EPS, the presence of which has been correlated with the fouling potential of bacteria. The presence of α-glycoside linkages was further confirmed by 13C NMR analysis. The 13C NMR analysis also showed that the EPS produced by these bacteria is chemically similar to foulants obtained from biofouled RO membranes in previous studies. Therefore, our results support the hypothesis that the majority of substances that cause fouling on RO membranes originate from bacteria. Investigation using 1H NMR showed that the EPS contained a high abundance of hydrophobic compounds, and these compounds can lead to flux decline in the membrane processes. Genome sequencing of the isolates showed that they represent novel species of bacteria belonging to the genus Bacillus. Examination of genomes showed that these bacteria carry carbohydrates-active enzymes that play a role in the production of polysaccharides. Further genomic studies allowed us to identify proteins involved in the biosynthesis of EPS and flagella involved in biofilm formation. These analyses provide a glimpse into the physicochemical properties of EPS found on the RO membrane. This knowledge can be useful in the rational design of biofilm control treatments for the RO membrane.

Aminated Rapeseed Husks (Brassica napus) as an Effective Sorbent for Removing Anionic Dyes from Aqueous Solutions

“…The FTIR spectra of rapeseed husks suggests that they contain polysaccharides, lignins, and proteins ( Figure 1 ). Polysaccharide-specific peaks can be found in the range of 1400–900 cm −1 [ 24 ]. The presence of C-O-C glycosidic bonds typical of saccharide rings is indicated by peaks visible at 1201 cm −1 , 1144 cm −1 , 1048 cm −1 , and 1024 cm −1 [ 25 ].…”

The Use of Rapeseed Husks to Remove Acidic and Basic Dyes from Aquatic Solutions

“…The FTIR spectrum of rapeseed husks (Figure 1) was typical of the lignocellulosic plant biomass. Peaks in the range of 1400-900 cm −1 were characteristic for bonds and functional groups of polysaccharides present in the material [26]. The peaks visible at 1024 cm −1 ; 1048 cm −1 ; 1144 cm −1 ; and also 1201 cm −1 may be ascribed to the C-O-C bond found in the aromatic rings of cellulose and hemicellulose [27].…”

Interaction of Silica Nanoparticles with Microalgal Extracellular Polymers

“…The interactions between isolated EPS and SiO2 NPs in their mixture (EPS + SiO2 NPs) were further investigated by FTIR spectroscopy. Since EPS is a complex mixture of biological material including polysaccharides, proteins, lipids, and nucleic acids, the FTIR spectrum of EPS alone is rather difficult to untangle [41][42][43]. With the aim of detecting The interactions between isolated EPS and SiO 2 NPs in their mixture (EPS + SiO 2 NPs) were further investigated by FTIR spectroscopy.…”

“…With the aim of detecting The interactions between isolated EPS and SiO 2 NPs in their mixture (EPS + SiO 2 NPs) were further investigated by FTIR spectroscopy. Since EPS is a complex mixture of biological material including polysaccharides, proteins, lipids, and nucleic acids, the FTIR spectrum of EPS alone is rather difficult to untangle [41][42][43]. With the aim of detecting and ultimately characterizing the interaction between EPS and NPs in assigning the FTIR spectrum of their mixture, we focused on the spectral range 1850-950 cm −1 which most exhaustively reflects the involvement of the individual functional groups of the constituent components in the formation of their supramolecular assemblies (Figure 4).…”