Related Experiment Video
Updated: Aug 7, 2026
11:35
Replication of the Ordered, Nonredundant Library of Pseudomonas aeruginosa strain PA14 Transposon Insertion Mutants
Published on: May 4, 2018
Chromate resistance plasmid in Pseudomonas fluorescens
Journal of Bacteriology
|September 1, 1983
Summary
Chromate resistance in Pseudomonas fluorescens LB300 is determined by a specific plasmid (pLHB1). This plasmid, when transferred to other bacteria like Escherichia coli, also confers resistance to chromate, highlighting its role in heavy metal tolerance.
Area of Science:
- Environmental Microbiology
- Bacterial Genetics
- Bioremediation
Background:
- Pseudomonas fluorescens LB300 was isolated from chromium-contaminated sediment.
- Chromate contamination poses environmental and health risks.
- Understanding microbial resistance mechanisms is crucial for bioremediation strategies.
Purpose of the Study:
- To investigate the genetic basis of chromate resistance in Pseudomonas fluorescens LB300.
- To determine if the resistance phenotype is transferable via plasmids.
Main Methods:
- Isolation of Pseudomonas fluorescens LB300 from contaminated environmental samples.
- Plasmid curing using mitomycin C and spontaneous segregation to eliminate pLHB1.
- Transformation experiments using purified pLHB1 plasmid DNA.
- Conjugation experiments to transfer pLHB1 to Escherichia coli.
Main Results:
- Loss of the plasmid pLHB1 resulted in a simultaneous loss of chromate resistance.
- Re-introduction of pLHB1 restored the chromate resistance phenotype.
- Transfer of pLHB1 to Escherichia coli conferred chromate resistance in the recipient strain.
Conclusions:
- Chromate resistance in Pseudomonas fluorescens LB300 is plasmid-specified by pLHB1.
- The pLHB1 plasmid carries the genetic determinants for chromate resistance.
- This plasmid-mediated resistance can be transferred between bacterial species, with implications for heavy metal adaptation in microbial communities.
Related Concept Videos
00:57Antibiotic Selection
Overview
01:28Plasmids
Plasmids are extrachromosomal DNA molecules found in bacteria, archaea, and some eukaryotic microbes like yeast. These small, circular DNA structures typically contain fewer than 30 genes, although some may exist linearly. Plasmids vary in their number within a cell, known as copy number. Single-copy plasmids are present in one copy per cell and multi-copy plasmids are present in multiple copies, reaching over 100 copies per cell.Plasmids usually replicate independently of the chromosomal DNA...
01:25Mechanism of Antibiotic Resistance in MRSA
Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...