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

Muhammad Fauzul Imron,Siti Rozaimah Sheikh Abdullah,Setyo Budi Kurniawan

doi:10.1186/s42834-021-00088-6

Muhammad Fauzul Imron, Siti Rozaimah Sheikh Abdullah + Show 1 more

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https://doi.org/10.1186/s42834-021-00088-6

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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.

Highlights

Heavy metal contamination in surface water and groundwater is a global concern
FZ-1, FZ-2, FZ-3, and FZ-4 were identified as Vibrio damsela, P. aeruginosa, Pseudomonas stutzeri, and P. fluorescens, respectively, with a similarity percentage of more than 90%
The results indicated that a higher heavy metal concentration up to 15 mg L− 1 produces a higher diameter of clear zone (DCZ) value indicating more severe toxicity, but at 20 mg L− 1 of heavy metal concentration, the DCZ value slightly decreases

Summary

Introduction

Heavy metal contamination in surface water and groundwater is a global concern. Heavy metals may pose chronic and even acute health hazards to living organisms, including humans. Landfill leachate contains various heavy metals, such as Hg, Pb, Zn, Cr, Mg, and Cd. Agamuthu and Fauziah [5] reported that Cd, Cr, Cu, Pb, Zn, and Mg were found in leachate with concentrations of 0.002, 0.006, 0.005, 0.15, 0.15, and 7.48 mg L− 1, respectively. Xue et al [6] found that the concentrations of Pb, Zn, Cr, Cd, and Cu in landfill leachate were 0.36, 0.27, 0.11, 0.2, and 0.21 mg L− 1, respectively. Leachate can pollute groundwater and pose risks to human health, such as bloody diarrhea, dehydration, renal failure, cancer, hypertension, pneumonitis, and anemia [7]

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