Screening strains for microbial biosorption technology of cadmium. (July 2020)

• Record Type: Journal Article
• Authors: Huang, Haojie; Jia, Qingyun; Jing, Weixin; Dahms, Hans-Uwe; Wang, Lan
• Is Part Of: Chemosphere. Volume 251(2020)
• Publication Date: 2020-07
• Subjects: Biosorption technology -- Trace metal -- Biofilm -- Escherichia coli -- Bacillus subtilis -- Saccharomyces cerevisiae.; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.126428
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Heavy metals contaminate the environment and provide a threat to public health through drinking water and food chain. Microbial biosorption technology provides a more economical and competitive solution for bioremediation of toxicants such as heavy metals, and microbial genetic modification may modify microbes towards optimal sorption. It is very important to screen suitable strains for this purpose. In this study, three different types of microorganisms Escherichia coli, Bacillus subtilis and Saccharomyces cerevisiae were isolated and identified, from uncontaminated soils, and compared their sorption differences with respect to cadmium (Cd 2+ ). We evaluated the effects of contact time and initial concentration on Cd 2+ uptake, and found pseudo-second-order kinetic models were more suitable to describe biosorption processes. Adsorption isotherms were used to reflect their biosorption capacity. The maximum biosorption capacities of three strains calculated by the Langmuir model were 37.764, 56.497, and 22.437 mg Cd/g biomass, respectively. In bacteria, Cd 2+ biosorption mainly occurred on cell wall, while the difference in biosorption between yeast inside and outside the cell was not significant. We found that due to the structural differences, the removal rate of E. coli surface decreased at a high concentration, while S. cerevisiae still had a lower biosorption capacity. FTIR spectroscopy reflected the difference in functional groups involved in biosorption by three strains. SEM-EDS analysis showed the binding of Cd 2+ to microorganisms mainly relied on ion exchange mechanism. Based on the above results, we suggested that B. subtilis is more suitable to get genetically modified for heavy metal biosorption. Graphical abstract: Image 1 Highlights: Bacillus subtilis showed a better cadmium biosorption capacity than other strains. There were more functional groups involved in Bacillus subtilis Cd 2+ biosorption. Ion exchange appeared as the main mechanism for microorganisms to remove Cd 2+ .