scholarly journals A genomic perspective of metal-resistant bacteria from gold particles: Possible survival mechanisms during gold biogeochemical cycling

2020 ◽  
Vol 96 (7) ◽  
Author(s):  
Santonu Kumar Sanyal ◽  
Frank Reith ◽  
Jeremiah Shuster

ABSTRACT A bacterial consortium was enriched from gold particles that ‘experienced’ ca. 80 years of biotransformation within waste-rock piles (Australia). This bacterial consortium was exposed to 10 µM AuCl3 to obtain Au-tolerant bacteria. From these isolates, Serratia sp. and Stenotrophomonas sp. were the most Au-tolerant and reduced soluble Au as pure gold nanoparticles, indicating that passive mineralisation is a mechanism for mediating the toxic effect of soluble Au produced during particle dissolution. Genome-wide analysis demonstrated that these isolates also possessed various genes that could provide cellular defence enabling survival under heavy-metal stressed condition by mediating the toxicity of heavy metals through active efflux/reduction. Diverse metal-resistant genes or genes clusters (cop, cus, czc, zntand ars) were detected, which could confer resistance to soluble Au. Comparative genome analysis revealed that the majority of detected heavy-metal resistant genes were similar (i.e. orthologous) to those genes of Cupriavidus metallidurans CH34. The detection of heavy-metal resistance, nutrient cycling and biofilm formation genes (pgaABCD, bsmAandhmpS) may have indirect yet important roles when dealing with soluble Au during particle dissolution. In conclusion, the physiological and genomic results suggest that bacteria living on gold particles would likely use various genes to ensure survival during Au-biogeochemical cycling.

2020 ◽  
Vol 727 ◽  
pp. 138698 ◽  
Author(s):  
Santonu Kumar Sanyal ◽  
Joël Brugger ◽  
Barbara Etschmann ◽  
Stephen M. Pederson ◽  
P.W. Jaco Delport ◽  
...  

2018 ◽  
Author(s):  
Mohammed Elbediwi ◽  
Yan Li ◽  
Narayan Paudyal ◽  
Hang Pan ◽  
Xiaoliang Li ◽  
...  

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Muhammad Fauzul Imron ◽  
Setyo Budi Kurniawan ◽  
Siti Rozaimah Sheikh Abdullah

AbstractLeachate 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.


2018 ◽  
Vol 7 (1) ◽  
pp. 28-40
Author(s):  
Bikram Gautam ◽  
Rameshwar Adhikari

Wastewater treatment plant is a potential reservoir contributing to the evolution and spread of heavy metal and antibiotic resistant bacteria. The pollutants such as biocides, antibiotics, heavy metals are to be feared for as they have been known to evoke resistance in microorganisms in such polluted environment. The aim of this study was to the isolate bacteria from the treated wastewater and assess the resistance pattern of the isolates against antibiotics and heavy metals. Grab sampling was performed from April to June 2017, from the treated effluent from the secondary treatment plant. To assess the resistance pattern for antibiotic(s) and heavy metal(s), antibiotic susceptibility test and minimum inhibitory concentration by cup well method were performed respectively. Staphylococcus aureus, Enterococcus faecalis, Citrobacter freundii, Escherichia coli, Enterobacter aerogenes, Proteus mirabilis, P. vulgaris, Salmonella Typhi, Pseudomonas aeruginosa were isolated. Multi drug and heavy metal resistant isolates were screened. Fisher’s exact test revealed that there is a significant association (p< 0.001) between antibiotic resistance pattern and resistance patterns at dilution of 2500 g/L (25%). Cramer’s V test revealed that the effect size of antibiotic resistance pattern and heavy metal resistance pattern at dilution 2500 g/L is medium. P. aeruginosa was able to resist the metal concentration up to 10000 g/L (100%) dilution of Fe++. Heavy metal resistant bacteria can be safely used to lower chemical concentration in the environment once their harmful genes are edited, knocked etc. so that risks of evoking antibiotic resistance could be minimized. 


2015 ◽  
Vol 3 (1) ◽  
Author(s):  
Terence Kanzil ◽  
Fatimawali . ◽  
Aaltje Manampiring

Abstract: Mercury is a toxic heavy metal that is used for dental fillings in the form of amalgam. To reduce the toxic effects produced by mercury, mercury resistant bacteria can be used. Bacillus sp is a gram-positive bacteria that is resistant to mercury. Besides having the mer operon genes that can transform Hg2+ to Hg0 that is less toxic, Bacillus sp bacteria also produce esterase that cause these bacteria resistant to erythromycin antibiotic. Erythromycin is a macrolide class of antibiotic used for the treatment of diseases caused by Gram-positive bacteria, especially Staphylococcus and Diphtheroids. To determine the resistance of Bacillus sp bacteria against mercury and erythromycin antibiotic. This study used a descriptive exploratory method with samples of bacteria and mercury are already available in the Laboratory of Pharmaceutical Microbiology. Based on the research that has been conducted, showed that the Bacillus sp bacteria is resistant to mercury and erythromycin.Keywords: bacteria, bacillus sp, resistant, mercury, erythromycinAbstrak: Merkuri merupakan logam berat bersifat toksik yang digunakan untuk penambalan gigi dalam bentuk amalgam. Untuk mengurangi efek toksik yang dihasilkan oleh merkuri, dapat digunakan bakteri resisten merkuri. Bakteri Bacillus sp merupakan bakteri gram positif yang resisten terhadap merkuri. Selain memiliki gen mer operon yang dapat mengubah Hg2+ menjadi Hg0 yang kurang toksik, bakteri Bacillus sp juga membentuk esterase yang menyebabkan terjadinya resisten bakteri ini terhadap antibiotik eritromisin. Eritromisin adalah antibiotik golongan makrolid yang digunakan untuk pengobatan penyakit akibat bakteri Gram positif khususnya Staphylococcus dan Diphtheroids. Untuk mengetahui resistensi bakteri Bacillus sp terhadap merkuri dan antibiotik eritromisin. Penelitian ini menggunakan metode deskriptif eksploratif dengan sampel bakteri dan merkuri yang sudah tersedia di Laboratorium Mikrobiologi Farmasi. Berdasarkan hasil penelitian yang telah dilakukan, diperoleh bahwa bakteri Bacillus sp resisten terhadap merkuri dan eritromisin.Kata Kunci: bakteri, bacillus sp, resisten, merkuri, eritromisin


Author(s):  
Zigang Li ◽  
Peng Wang ◽  
Xiaoyu Yue ◽  
Jingtao Wang ◽  
Baozeng Ren ◽  
...  

The objective of this study was to explore the effect of heavy metal-resistant bacteria and biochar (BC) on reducing heavy metal accumulation in vegetables and the underlying mechanism. We tested Bacillus thuringiensis HC-2, BC, and BC+HC-2 for their ability to immobilize Cd and Pb in culture solution. We also studied the effects of these treatments on the dry weight and Cd and Pb uptake of radish in metal-contaminated soils under field conditions and the underlying mechanism. Treatment with HC-2, BC, and BC+HC-2 significantly reduced the water-soluble Cd (34–56%) and Pb (31–54%) concentrations and increased the pH and NH4+ concentration in solution compared with their vales in a control. These treatments significantly increased the dry weight of radish roots (18.4–22.8%) and leaves (37.8–39.9%) and decreased Cd (28–94%) and Pb (22–63%) content in the radish roots compared with the control. Treatment with HC-2, BC, and BC+HC-2 also significantly increased the pH, organic matter content, NH4+ content, and NH4+/NO3− ratio of rhizosphere soils, and decreased the DTPA-extractable Cd (37–58%) and Pb (26–42%) contents in rhizosphere soils of radish. Furthermore, BC+HC-2 had higher ability than the other two treatments to protect radish against Cd and Pb toxicity and increased radish biomass. Therefore, Bacillus thuringiensis HC-2 combined with biochar can ensure vegetable safety in situ for the bioremediation of heavy metal-polluted farmland.


Chemotherapy ◽  
2017 ◽  
Vol 62 (4) ◽  
pp. 262-268 ◽  
Author(s):  
Xiaoxiao Zhang ◽  
Jia Du ◽  
Cui Zhou ◽  
Jianming Cao ◽  
Hong Lu ◽  
...  

Aims: This study aimed to analyze the clinical data and characteristics of an NDM-1 (New Delhi metallo-β-lactamase-1)-producing Klebsiella pneumoniae isolated from the bloodstream of a leukemia patient. Materials and Methods: A retrospective analysis was used for the clinical data of the patient. The modified Hodge test (MHT) and ethylenediaminetetraacetic acid (EDTA)-disk synergy test were used for detecting metallo-β-lactamase. Antibiotic resistance was determined using the agar dilution method. PCR was used to identify resistance genes. S1-PFGE (S1 nuclease/pulsed-field gel electrophoresis) and Southern blot hybridization were performed to determine the location of blaNDM-1. A conjugation experiment was used to confirm the transferable characteristics of the resistant genes. Multilocus sequence typing (MLST) was also performed. Results: The patient developed bloodstream infections caused by this NDM-1-producing strain and died due to worsening of the condition. The strain was highly resistant to β-lactam antibiotics and coharbored blaNDM-1, qnrB, and blaCTX-M-9 genes. Southern blot confirmed that blaNDM-1 was located on a plasmid of approximately 55 kb and could be transferred to Escherichia coli J53. MLST analysis showed that this strain belonged to an uncommon sequence type ST1224. Conclusion: The coexistence of various resistant genes is the mechanism for resistance to most antibiotics. Additionally, infections caused by multi-drug resistant bacteria increase the mortality of patients with immunodeficiency, which alerts clinicians to establish a rational and effective combination drug therapy.


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