Biosorption of Heavy Metals by the Bacterial Exopolysaccharide FucoPol

Abstract

Despite the efforts for minimizing the usage of heavy metals, anthropogenic activities still generate high amounts of wastewater containing these contaminants that cause significant health and environmental problems. Given the drawbacks of the conventional physical and chemical methods currently used, natural biosorbents (microbial cells or their products) arise as promising environmentally friendly alternatives. In this study, the binding efficiency of the polysaccharide secreted by Enterobacter A47, FucoPol, towards lead (Pb2+), cobalt (Co2+), copper (Cu2+) and zinc (Zn2+) cations was demonstrated. FucoPol revealed a higher performance for the biosorption of Pb2+, with a maximum overall metal removal of 93.9 ± 5.3% and a specific metal uptake of 41.1 ± 2.3 mg/gEPS, from a Pb2+ solution with an initial concentration of 10 mg/L, by a 5 g/L FucoPol solution. The overall metal removal decreased considerably (≤31.3 ± 1.6%) for higher Pb2+ concentrations (48 and 100 mg/L) probably due to the saturation of FucoPol’s binding sites. Pb2+ removal was also less efficient (66.0 ± 8.2%) when a higher FucoPol concentration (10 g/L) was tested. Pb2+ removal efficiency of FucoPol was maximized at pH 4.3, however, it was affected by lower pH values (2.5–3.3). Moreover, the FucoPol’s sorption performance was unaffected (overall metal removal: 91.6–93.9%) in the temperature range of 5–40 °C. These findings demonstrate FucoPol’s great potential for utilization as a biodegradable and safe biosorbent for treating waters and wastewaters contaminated with Pb2+.

Extraction of the Bacterial Extracellular Polysaccharide FucoPol by Membrane-Based Methods: Efficiency and Impact on Biopolymer Properties

“…The results obtained in this study show that Method 2 (ultrafiltration with the 30 kDa membrane—sample F-2 30 ) reached the best performance in terms of operation time and water consumption, together with good FucoPol recovery ( Table 5 ). Compared to Method 1 (diafiltration-ultrafiltration with a 100 kDa membrane—sample F-1 100 ) that was used in previous studies [ 13 , 28 , 33 ], there was a reduction of the extraction time from 105 ± 6 min to 66 ± 6 min and a reduction of the water consumption by 55%. This is translated in terms of energy, water and time savings for the overall FucoPol production process that are of special relevance for the process scale up.…”

“…This study focused on optimizing the downstream procedure for FucoPol recovery from Enterobacter A47 cultivation broth. Three methods were designed and tested, using membranes of two different MWCO, namely, 100 kDa, which had been utilized in previous studies [ 13 , 33 ], and 30 kDa. The performance of each method was evaluated in terms of operating time, water consumption, and polymer recovery.…”

Characterization and Biotechnological Potential of Extracellular Polysaccharides Synthesized by Alteromonas Strains Isolated from French Polynesia Marine Environments

“…Protein content was quantified by a modified Lowry method, as described by Concórdio-Reis et al [ 52 ]. For the determination of inorganic content, lyophilized EPS samples (~40 mg) were placed at 100 °C until a constant weight was attained.…”

“…The dried EPS samples were subjected to pyrolysis (550 °C, 24 h), and weighted for the gravimetric quantification of the inorganic content. Acyl groups were analyzed by HPLC with an Aminex HPX-87H 300 × 7.8 mm column (Biorad, Hercules, CA, USA) coupled with UV detector (210 nm), as described by Concórdio-Reis et al [ 52 ]. Sulfate concentration in the hydrolysates was determined by HPLC using a Thermo Ionpac AS9-HC 250 × 4 mm column and a Thermo Ionpac AG11HC column (Thermo Scientific™ Dionex™, Sunnyvale, CA, USA), equipped with a conductivity detector.…”

Emerging technologies for mixed industrial wastewater treatment in developing countries: An overview

“…Biosorption is one of the most prominent strategies to remove metals from a contaminated environment. The process utilizes either live or dead microbial cells and microbial metabolic products such as polymers (Concórdio‐Reis et al., 2020). Binding of metals occurs by either physisorption involving Van der Waals attractions or chemisorption involving chelation, precipitation, ion exchange processes, and metal complexation by cell components (Igiri et al., 2018; Javanbakht et al., 2014).…”