Antibiotic and Heavy Metal Resistance in Bacteria from Contaminated Agricultural Soil: Insights from a New Zealand Airstrip
Background/Objectives: Agricultural soils accumulate inorganic contaminants from the application of phosphate fertilisers. An airstrip located at Belmont Regional Park (BRP), near Wellington, New Zealand, has been found to have a gradient of cadmium contamination due to spillage of superphosphate fe...
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MDPI AG
2025-02-01
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| Series: | Antibiotics |
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| Online Access: | https://www.mdpi.com/2079-6382/14/2/192 |
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| author | Ali Heydari Nick D. Kim Patrick J. Biggs Jacqui Horswell Gerty J. H. P. Gielen Alma Siggins Collette Bromhead Juan Carlos Meza-Alvarado Barry R. Palmer |
| author_facet | Ali Heydari Nick D. Kim Patrick J. Biggs Jacqui Horswell Gerty J. H. P. Gielen Alma Siggins Collette Bromhead Juan Carlos Meza-Alvarado Barry R. Palmer |
| author_sort | Ali Heydari |
| collection | DOAJ |
| description | Background/Objectives: Agricultural soils accumulate inorganic contaminants from the application of phosphate fertilisers. An airstrip located at Belmont Regional Park (BRP), near Wellington, New Zealand, has been found to have a gradient of cadmium contamination due to spillage of superphosphate fertiliser. Methods: Soil samples from the BRP airstrip with a gradient of cadmium contamination, were used as a novel source to explore bacterial communities’ resistance to heavy metals (HMs) and any co-selected antibiotic (Ab) resistance. Results: Differences between BRP soil samples with higher levels of HMs compared to those with lower HM concentrations showed significantly more bacterial isolates resistant to both HMs (40.6% versus 63.1% resistant to 0.01 mM CdCl<sub>2</sub>, <i>p</i> < 0.05) and Abs (23.4% versus 37.8% resistant to 20 μg/mL tetracycline, <i>p</i> < 0.05) in soils with higher initial levels of HMs (1.14 versus 7.20 mg kg<sup>−1</sup> Cd). Terminal restriction fragment length polymorphism (TRFLP) and 16S rDNA next-generation sequencing profiling investigated changes in HM-induced bacterial communities. Significant differences were observed among the bacterial community structures in the selected BRP soil samples. Conjugative transfer of cadmium resistance from 23–38% of cadmium-resistant isolates to a characterised recipient bacterial strain in vitro suggested many of these genes were carried by mobile genetic elements. Transconjugants were also resistant to zinc, mercury, and Abs. Higher levels of HMs in soil correlated with increased resistance to HMs, Abs, and elevated levels of HMs thus disturbed the bacterial community structure in BRP soil significantly. Conclusions: These findings suggest that HM contamination of agricultural soil can select for Ab resistance in soil bacteria with potential risks to human and animal health. |
| format | Article |
| id | doaj-art-6ae6b89975e240b68137fa9668ded7d4 |
| institution | DOAJ |
| issn | 2079-6382 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Antibiotics |
| spelling | doaj-art-6ae6b89975e240b68137fa9668ded7d42025-08-20T03:11:06ZengMDPI AGAntibiotics2079-63822025-02-0114219210.3390/antibiotics14020192Antibiotic and Heavy Metal Resistance in Bacteria from Contaminated Agricultural Soil: Insights from a New Zealand AirstripAli Heydari0Nick D. Kim1Patrick J. Biggs2Jacqui Horswell3Gerty J. H. P. Gielen4Alma Siggins5Collette Bromhead6Juan Carlos Meza-Alvarado7Barry R. Palmer8School of Health Sciences, Massey University, Wellington 6021, New ZealandSchool of Health Sciences, Massey University, Wellington 6021, New ZealandSchool of Food Technology and Natural Sciences, Massey University, Palmerston North 4410, New ZealandSchool of Health Sciences, Massey University, Wellington 6021, New ZealandScion, Rotorua 3010, New ZealandSchool of Biological and Chemical Sciences, University of Galway, H91 TK33 Galway, IrelandSchool of Health Sciences, Massey University, Wellington 6021, New ZealandSchool of Health Sciences, Massey University, Wellington 6021, New ZealandSchool of Health Sciences, Massey University, Wellington 6021, New ZealandBackground/Objectives: Agricultural soils accumulate inorganic contaminants from the application of phosphate fertilisers. An airstrip located at Belmont Regional Park (BRP), near Wellington, New Zealand, has been found to have a gradient of cadmium contamination due to spillage of superphosphate fertiliser. Methods: Soil samples from the BRP airstrip with a gradient of cadmium contamination, were used as a novel source to explore bacterial communities’ resistance to heavy metals (HMs) and any co-selected antibiotic (Ab) resistance. Results: Differences between BRP soil samples with higher levels of HMs compared to those with lower HM concentrations showed significantly more bacterial isolates resistant to both HMs (40.6% versus 63.1% resistant to 0.01 mM CdCl<sub>2</sub>, <i>p</i> < 0.05) and Abs (23.4% versus 37.8% resistant to 20 μg/mL tetracycline, <i>p</i> < 0.05) in soils with higher initial levels of HMs (1.14 versus 7.20 mg kg<sup>−1</sup> Cd). Terminal restriction fragment length polymorphism (TRFLP) and 16S rDNA next-generation sequencing profiling investigated changes in HM-induced bacterial communities. Significant differences were observed among the bacterial community structures in the selected BRP soil samples. Conjugative transfer of cadmium resistance from 23–38% of cadmium-resistant isolates to a characterised recipient bacterial strain in vitro suggested many of these genes were carried by mobile genetic elements. Transconjugants were also resistant to zinc, mercury, and Abs. Higher levels of HMs in soil correlated with increased resistance to HMs, Abs, and elevated levels of HMs thus disturbed the bacterial community structure in BRP soil significantly. Conclusions: These findings suggest that HM contamination of agricultural soil can select for Ab resistance in soil bacteria with potential risks to human and animal health.https://www.mdpi.com/2079-6382/14/2/192heavy metal resistancebacteriasoilantimicrobial resistancePICT |
| spellingShingle | Ali Heydari Nick D. Kim Patrick J. Biggs Jacqui Horswell Gerty J. H. P. Gielen Alma Siggins Collette Bromhead Juan Carlos Meza-Alvarado Barry R. Palmer Antibiotic and Heavy Metal Resistance in Bacteria from Contaminated Agricultural Soil: Insights from a New Zealand Airstrip Antibiotics heavy metal resistance bacteria soil antimicrobial resistance PICT |
| title | Antibiotic and Heavy Metal Resistance in Bacteria from Contaminated Agricultural Soil: Insights from a New Zealand Airstrip |
| title_full | Antibiotic and Heavy Metal Resistance in Bacteria from Contaminated Agricultural Soil: Insights from a New Zealand Airstrip |
| title_fullStr | Antibiotic and Heavy Metal Resistance in Bacteria from Contaminated Agricultural Soil: Insights from a New Zealand Airstrip |
| title_full_unstemmed | Antibiotic and Heavy Metal Resistance in Bacteria from Contaminated Agricultural Soil: Insights from a New Zealand Airstrip |
| title_short | Antibiotic and Heavy Metal Resistance in Bacteria from Contaminated Agricultural Soil: Insights from a New Zealand Airstrip |
| title_sort | antibiotic and heavy metal resistance in bacteria from contaminated agricultural soil insights from a new zealand airstrip |
| topic | heavy metal resistance bacteria soil antimicrobial resistance PICT |
| url | https://www.mdpi.com/2079-6382/14/2/192 |
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