Plasmid-determined resistance to tellurium compounds

Area of Science:

• Microbiology
• Genetics
• Environmental Science

Background:

• Gram-negative bacteria possess resistance mechanisms to various toxic compounds.
• Plasmids are known to carry genes conferring resistance, facilitating horizontal gene transfer.
• Tellurium compounds, like tellurite and tellurate, are environmental contaminants with antimicrobial properties.

Purpose of the Study:

• To identify and characterize transferable plasmids conferring resistance to potassium tellurite and tellurate in gram-negative bacteria.
• To investigate the relationship between tellurium resistance and other known resistance mechanisms.
• To determine the specific plasmid incompatibility groups associated with tellurium resistance in different bacterial species.

Main Methods:

• Isolation and characterization of plasmids from resistant bacterial strains.
• Determination of minimal inhibitory concentrations (MICs) for tellurite and tellurate.
• Plasmid incompatibility grouping using established methods.
• Testing for cross-resistance to heavy metals and antibiotics.

Main Results:

• Transferable plasmids conferring tellurite and tellurate resistance were identified in gram-negative bacteria.
• This resistance was independent of resistance to mercury, silver, arsenic, and antibiotics.
• In Escherichia coli, plasmids increased tellurite MIC by 100-fold and tellurate resistance by 10-fold, often belonging to incompatibility group S.
• In Pseudomonas aeruginosa, tellurium resistance was linked to incompatibility group P-2, with a 5- to 10-fold increase in resistance.

Conclusions:

• Transferable plasmids are a significant mechanism for tellurium resistance in gram-negative bacteria.
• Tellurium resistance is encoded by distinct genetic elements, separate from common antibiotic resistance genes.
• Specific plasmid incompatibility groups (S and P-2) are associated with tellurium resistance in E. coli and P. aeruginosa, respectively.