Resistance of bacteria isolated from leachate to heavy metals and the removal of Hg by Pseudomonas aeruginosa strain FZ-2 at different salinity levels in a batch biosorption system

Abstract

Leachate is produced from sanitary landfills containing various pollutants, including heavy metals. This study aimed to determine the resistance of bacteria isolated from non-active sanitary landfill leachate to various heavy metals and the effect of salinity levels on the removal of Hg by the isolated bacterium. Four dominant bacteria from approximately 33 × 1017 colony-forming units per mL identified as Vibrio damsela, Pseudomonas aeruginosa, Pseudomonas stutzeri, and Pseudomonas fluorescens were isolated from non-active sanitary landfill leachate. Heavy metal resistance test was conducted for Hg, Cd, Pb, Mg, Zn, Fe, Mn, and Cu (0–20 mg L− 1). The removal of the most toxic heavy metals by the most resistant bacteria was also determined at different salinity levels, i.e., fresh water (0‰), marginal water (10‰), brackish water (20‰), and saline water (30‰). Results showed that the growth of these bacteria is promoted by Fe, Mn, and Cu, but inhibited by Hg, Cd, Pb, Mg, and Zn. The minimum inhibitory concentration (MIC) of all the bacteria in Fe, Mn, and Cu was > 20 mg L− 1. The MIC of V. damsela was 5 mg L− 1 for Hg and > 20 mg L− 1 for Cd, Pb, Mg, and Zn. For P. aeruginosa, MIC was > 20 mg L− 1 for Cd, Pb, Mg, and Zn and 10 mg L− 1 for Hg. Meanwhile, the MIC of P. stutzeri was > 20 mg L− 1 for Pb, Mg, and Zn and 5 mg L− 1 for Hg and Cd. The MIC of P. fluorescens for Hg, Pb, Mg, and Zn was 5, 5, 15, and 20 mg L− 1, respectively, and that for Cd was > 20 mg L− 1. From the MIC results, Hg is the most toxic heavy metal. In marginal water (10‰), P. aeruginosa FZ-2 removed up to 99.7% Hg compared with that in fresh water (0‰), where it removed only 54% for 72 h. Hence, P. aeruginosa FZ-2 is the most resistant to heavy metals, and saline condition exerts a positive effect on bacteria in removing Hg.

Comparative Metagenomic Study of Rhizospheric and Bulk Mercury-Contaminated Soils in the Mining District of Almadén

“…have a high biotechnological interest and have been studied for their characteristics as PGPR ( Yasmeen et al, 2021 ). The bioremediation capacity of Hg is well known ( González et al, 2021 ; Imron et al, 2021 ; Robas et al, 2021a ). Therefore, a study of its potential use in the remediation of contaminated soils and look for non-phytopathogenic specific strains is of interest.…”

Practical limitations of bioaugmentation in treating heavy metal contaminated soil and role of plant growth promoting bacteria in phytoremediation as a promising alternative approach

“…Certain plant species can adsorb and accumulate certain heavy metal type inside their cell, thus resulting in higher removal of heavy metals from the contaminated medium ( Li et al., 2020 ). In the search of the hyper accumulator species, certain criteria need to be concerned, including the species should be nonedible plants ( Ekperusi et al., 2019 ; Shahid et al., 2020 ), highest concentration that can be tolerated by plants (maximum tolerable concentration) ( Purwanti et al., 2018a , Purwanti et al., 2018b ), minimum concentration of heavy metals that starts to inhibit the plant's growth (minimum inhibitory concentration) ( Imron et al., 2021 ), and perennial plant type is suggested to minimize harvesting that can increase operation and maintenance cost ( Al-Baldawi et al., 2015 ; Im et al., 2019 ).…”

“…In comparison, bioaccumulation initiates quickly and proceeds to a moderate stage allowing ion exchange or physical adsorption for metal attachment and transportation, based on metabolic activity involving ATP ( Srinath et al., 2002 ). Metal inside cells are generally accumulated in the form of complex–metal compounds, as the result of their resistance mechanisms through several enzymatic reactions ( Imron et al., 2021 ).…”

“…Both pathways typically involve enzymes to reduce or transform the toxic heavy metal before releasing the less toxic heavy metal into the ecosystem ( Jobby et al., 2018 ). The bound between functional groups or compounds in the bacterial cell wall may also occur as the resistance mechanisms to heavy metals ( Imron et al., 2021 ). The bounded metals and the functional group form minerals surrounding the cell walls, which also serve as further protection, commonly called as biomineralization ( Dhami et al., 2013 ; Zahoor et al., 2017 ).…”

Ecological impacts of ballast water loading and discharge: insight into the toxicity and accumulation of disinfection by-products

“…In addition, several researchers found cases of transporting Vibrio cholerae , which is a disease-causing pathogen in humans carried by the exchange of ballast water entering the Chesapeake Bay ( Cohen et al., 2012 ; Hallegraeff and Bolch, 1991 ; Purwanti et al., 2020 ). Therefore, a ballast water treatment system is required to minimize the risk of organism exchange ( Carney et al., 2017 ; Imron et al., 2021 ).…”