Heavy metal resistance of microorganisms from petroleum hydrocarbon contaminated soils located in Mersin, Turkey

ABSTRACT The symbiosis of the highly metal-resistant Sinorhizobium meliloti CCNWSX0020 and Medicago lupulina has been considered an efficient tool for bioremediation of heavy metal-polluted soils. However, the metal resistance mechanisms of S. meliloti CCNWSX00200 have not been elucidated in detail. Here we employed a comparative transcriptome approach to analyze the defense mechanisms of S. meliloti CCNWSX00200 against Cu or Zn exposure. Six highly upregulated transcripts involved in Cu and Zn resistance were identified through deletion mutagenesis, including genes encoding a multicopper oxidase (CueO), an outer membrane protein (Omp), sulfite oxidoreductases (YedYZ), and three hypothetical proteins (a CusA-like protein, a FixH-like protein, and an unknown protein), and the corresponding mutant strains showed various degrees of sensitivity to multiple metals. The Cu-sensitive mutant (ΔcueO) and three mutants that were both Cu and Zn sensitive (ΔyedYZ, ΔcusA-like, and ΔfixH-like) were selected for further study of the effects of these metal resistance determinants on bioremediation. The results showed that inoculation with the ΔcueO mutant severely inhibited infection establishment and nodulation of M. lupulina under Cu stress, while inoculation with the ΔyedYZ and ΔfixH-like mutants decreased just the early infection frequency and nodulation under Cu and Zn stresses. In contrast, inoculation with the ΔcusA-like mutant almost led to loss of the symbiotic capacity of M. lupulina to even grow in uncontaminated soil. Moreover, the antioxidant enzyme activity and metal accumulation in roots of M. lupulina inoculated with all mutants were lower than those with the wild-type strain. These results suggest that heavy metal resistance determinants may promote bioremediation by directly or indirectly influencing formation of the rhizobium-legume symbiosis. IMPORTANCE Rhizobium-legume symbiosis has been promoted as an appropriate tool for bioremediation of heavy metal-contaminated soils. Considering the plant-growth-promoting traits and survival advantage of metal-resistant rhizobia in contaminated environments, more heavy metal-resistant rhizobia and genetically manipulated strains were investigated. In view of the genetic diversity of metal resistance determinants in rhizobia, their effects on phytoremediation by the rhizobium-legume symbiosis must be different and depend on their specific assigned functions. Our work provides a better understanding of the mechanism of heavy metal resistance determinants involved in the rhizobium-legume symbiosis, and in further studies, genetically modified rhizobia harboring effective heavy metal resistance determinants may be engineered for the practical application of rhizobium-legume symbiosis for bioremediation in metal-contaminated soils.

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Analysis of the Genome of the Heavy Metal Resistant and Hydrocarbon-Degrading Rhizospheric Pseudomonas qingdaonensis ZCR6 Strain and Assessment of Its Plant-Growth-Promoting Traits

International Journal of Molecular Sciences ◽

10.3390/ijms23010214 ◽

2021 ◽

Vol 23 (1) ◽

pp. 214

Author(s):

Daria Chlebek ◽

Tomasz Płociniczak ◽

Sara Gobetti ◽

Agata Kumor ◽

Katarzyna Hupert-Kocurek ◽

...

Keyword(s):

Heavy Metal ◽

Plant Growth ◽

Contaminated Soils ◽

Growth Promotion ◽

Sulfur Metabolism ◽

Heavy Metal Resistance ◽

Metal Resistance ◽

Minimal Inhibitory Concentrations ◽

Plant Growth Promoting

The Pseudomonas qingdaonensis ZCR6 strain, isolated from the rhizosphere of Zea mays growing in soil co-contaminated with hydrocarbons and heavy metals, was investigated for its plant growth promotion, hydrocarbon degradation, and heavy metal resistance. In vitro bioassays confirmed all of the abovementioned properties. ZCR6 was able to produce indole acetic acid (IAA), siderophores, and ammonia, solubilized Ca3(PO4)2, and showed surface active properties and activity of cellulase and very high activity of 1-aminocyclopropane-1-carboxylic acid deaminase (297 nmol α-ketobutyrate mg−1 h−1). The strain degraded petroleum hydrocarbons (76.52% of the initial hydrocarbon content was degraded) and was resistant to Cd, Zn, and Cu (minimal inhibitory concentrations reached 5, 15, and 10 mM metal, respectively). The genome of the ZCR6 strain consisted of 5,507,067 bp, and a total of 5055 genes were annotated, of which 4943 were protein-coding sequences. Annotation revealed the presence of genes associated with nitrogen fixation, phosphate solubilization, sulfur metabolism, siderophore biosynthesis and uptake, synthesis of IAA, ethylene modulation, heavy metal resistance, exopolysaccharide biosynthesis, and organic compound degradation. Complete characteristics of the ZCR6 strain showed its potential multiway properties for enhancing the phytoremediation of co-contaminated soils. To our knowledge, this is the first analysis of the biotechnological potential of the species P. qingdaonensis.

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Co‐occurrence of antibiotic, biocide, and heavy metal resistance genes in bacteria from metal and radionuclide contaminated soils at the Savannah River Site

Microbial Biotechnology ◽

10.1111/1751-7915.13578 ◽

2020 ◽

Vol 13 (4) ◽

pp. 1179-1200 ◽

Cited By ~ 5

Author(s):

Jesse C. Thomas ◽

Adelumola Oladeinde ◽

Troy J. Kieran ◽

John W. Finger ◽

Natalia J. Bayona‐Vásquez ◽

...

Keyword(s):

Heavy Metal ◽

Resistance Genes ◽

Contaminated Soils ◽

Heavy Metal Resistance ◽

Savannah River Site ◽

Metal Resistance ◽

Savannah River ◽

River Site

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A New Klebsiella planticola Strain (Cd-1) Grows Anaerobically at High Cadmium Concentrations and Precipitates Cadmium Sulfide

Applied and Environmental Microbiology ◽

10.1128/aem.66.7.3083-3087.2000 ◽

2000 ◽

Vol 66 (7) ◽

pp. 3083-3087 ◽

Cited By ~ 68

Author(s):

Pramod K. Sharma ◽

David L. Balkwill ◽

Anatoly Frenkel ◽

Murthy A. Vairavamurthy

Keyword(s):

Heavy Metal ◽

Cadmium Sulfide ◽

Contaminated Soils ◽

Heavy Metal Resistance ◽

Metal Resistance ◽

Soils And Sediments ◽

Wide Range ◽

Klebsiella Planticola ◽

Marsh Sediments ◽

Salt Marsh Sediments

ABSTRACT Heavy metal resistance by bacteria is a topic of much importance to the bioremediation of contaminated soils and sediments. We report here the isolation of a highly cadmium-resistant Klebsiella planticola strain, Cd-1, from reducing salt marsh sediments. The strain grows in up to 15 mM CdCl2 under a wide range of NaCl concentrations and at acidic or neutral pH. In growth medium amended with thiosulfate, it precipitated significant amounts of cadmium sulfide (CdS), as confirmed by x-absorption spectroscopy. In comparison with various other strains tested, Cd-1 is superior for precipitating CdS in cultures containing thiosulfate. Thus, our results suggest that Cd-1 is a good candidate for the accelerated bioremediation of systems contaminated by high levels of cadmium.

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Characterisation of surfactant-expressing bacteria and their potential bioremediation properties from hydrocarbon-contaminated and uncontaminated soils

Access Microbiology ◽

10.1099/acmi.ac2020.po0506 ◽

2020 ◽

Vol 2 (7A) ◽

Author(s):

Raji Bamanga ◽

Yusuf Y. Deeni ◽

Andrew Spiers ◽

Scott Cameron

Keyword(s):

Heavy Metal ◽

Contaminated Soils ◽

Phenotypic Diversity ◽

Draft Genome ◽

Hierarchical Cluster ◽

Heavy Metal Resistance ◽

Metal Resistance ◽

Ex Situ ◽

Rdna Sequencing ◽

High Concentrations

We are investigating characteristics associated with oil degradation amongst bacteria isolated from clean and hydrocarbon contaminated soils from Nigeria and the UK.Our focus has been to identify bacteria expressing surfactants following isolation on Pseudomonas selective (PSA-CFC) and non-selective nutrient media and investigate the nature of surfactants, heavy metal resistance and hydrocarbon-degrading enzymes expressed by the bacteria. Of five sites sampled, a total of 1460 colonies were tested using the drop collapse assay, and 110 were found to express surfactants reducing liquid surface tensions as assessed by quantitative tensiometry to between 24.7 and 26.7 mN.m-1 (Tukey-Kramer HSD, α=0.05). We undertook a range of growth and behaviour-based assays on 60 selected strain which, when investigated by Hierarchical cluster analysis (HCA) demonstrated that this collection showed considerable phenotypic diversity. Eight out of the 60 strains could grow at a high temperature (50 °C), 35 of the 60 strains utilized diesel as a sole carbon source, and most of the strains could tolerate high concentrations (up to 20 mM) of heavy metals. Identification by 16S rDNA sequencing revealed that some of the strains belong to Pseudomonas, Bacillus, and Stenotrophomonas genera. We found using bioinformatics analysis of eight-selected draft genome sequences (AntiSMASH and RAST) NRPS-like (probable surfactants), cytochrome P450, catechol-1,2/2,3-dioxygenase, lipase, and heavy metal resistance gene sequences. We intend to use the information provided in this research to select strains for potential applications in in-situor ex-situ bioremediation of hydrocarbon-contaminated soils.

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Heavy Metal Tolerance Trend in Extended-Spectrum β-Lactamase Encoding Strains Recovered from Food Samples

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18094718 ◽

2021 ◽

Vol 18 (9) ◽

pp. 4718

Author(s):

Kashaf Junaid ◽

Hasan Ejaz ◽

Iram Asim ◽

Sonia Younas ◽

Humaira Yasmeen ◽

...

Keyword(s):

Heavy Metal ◽

Metal Tolerance ◽

Heavy Metal Tolerance ◽

Heavy Metal Resistance ◽

Metal Resistance ◽

Food Samples ◽

Esbl Production ◽

Extended Spectrum ◽

Retail Food ◽

Esbl Producers

This study evaluates bacteriological profiles in ready-to-eat (RTE) foods and assesses antibiotic resistance, extended-spectrum β-lactamase (ESBL) production by gram-negative bacteria, and heavy metal tolerance. In total, 436 retail food samples were collected and cultured. The isolates were screened for ESBL production and molecular detection of ESBL-encoding genes. Furthermore, all isolates were evaluated for heavy metal tolerance. From 352 culture-positive samples, 406 g-negative bacteria were identified. Raw food samples were more often contaminated than refined food (84.71% vs. 76.32%). The predominant isolates were Klebsiella pneumoniae (n = 76), Enterobacter cloacae (n = 58), and Escherichia coli (n = 56). Overall, the percentage of ESBL producers was higher in raw food samples, although higher occurrences of ESBL-producing E. coli (p = 0.01) and Pseudomonas aeruginosa (p = 0.02) were observed in processed food samples. However, the prevalence of ESBL-producing Citrobacter freundii in raw food samples was high (p = 0.03). Among the isolates, 55% were blaCTX-M, 26% were blaSHV, and 19% were blaTEM. Notably, heavy metal resistance was highly prevalent in ESBL producers. These findings demonstrate that retail food samples are exposed to contaminants including antibiotics and heavy metals, endangering consumers.

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Genome-Driven Discovery of Enzymes with Industrial Implications from the Genus Aneurinibacillus

Microorganisms ◽

10.3390/microorganisms9030499 ◽

2021 ◽

Vol 9 (3) ◽

pp. 499

Author(s):

Majid Rasool Kamli ◽

Nada A. Y. Alzahrani ◽

Nahid H. Hajrah ◽

Jamal S. M. Sabir ◽

Adeel Malik

Keyword(s):

Heavy Metal ◽

Enzyme Activities ◽

Heavy Metal Resistance ◽

Industrial Applications ◽

Metal Resistance ◽

The Family ◽

Antiviral Activities ◽

Genome Level ◽

Genome Analyses ◽

Unique Species

Bacteria belonging to the genus Aneurinibacillus within the family Paenibacillaceae are Gram-positive, endospore-forming, and rod-shaped bacteria inhabiting diverse environments. Currently, there are eight validly described species of Aneurinibacillus; however, several unclassified species have also been reported. Aneurinibacillus spp. have shown the potential for producing secondary metabolites (SMs) and demonstrated diverse types of enzyme activities. These features make them promising candidates with industrial implications. At present, genomes of 9 unique species from the genus Aneurinibacillus are available, which can be utilized to decipher invaluable information on their biosynthetic potential as well as enzyme activities. In this work, we performed the comparative genome analyses of nine Aneurinibacillus species representing the first such comprehensive study of this genus at the genome level. We focused on discovering the biosynthetic, biodegradation, and heavy metal resistance potential of this under-investigated genus. The results indicate that the genomes of Aneurinibacillus contain SM-producing regions with diverse bioactivities, including antimicrobial and antiviral activities. Several carbohydrate-active enzymes (CAZymes) and genes involved in heavy metal resistance were also identified. Additionally, a broad range of enzyme classes were also identified in the Aneurinibacillus pan-genomes, making this group of bacteria potential candidates for future investigations with industrial applications.

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