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Isolation and characterization of a plasmid from Lactobacillus fermentum conferring erythromycin resistance
1Unité d'Ecologie et de Physiologie du Système Digestif, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
Abstract:
Lactobacillus fermentum is a lactic acid bacterial species commonly found in the digestive tracts of pigs and rodents and also present in man. We characterized a 5.7-kb plasmid, pLEM3, conferring erythromycin resistance, which was isolated from a porcine strain of L. fermentum. Plasmid pLEM3 established efficiently in L. fermentum, conferred high-level erythromycin resistance (MIC > 1 mg/ml), and was segregationally stable. A deletion derivative of pLEM3, called pLEM5, was constructed and found to be as genetically stable as the parent. A multiple cloning site was inserted into pLEM5, generating plasmid pLEM7. Nucleotide sequence determination of pLEM5 revealed similarities with known genes. The replicon itself is a member of the pC194 family of rolling circle plasmids. The region responsible for erythromycin resistance was 98.2% identical to the erm gene of conjugative transposon Tn1545.
Insights
Researchers characterized pLEM3, a plasmid from Lactobacillus fermentum, which confers erythromycin resistance. This stable plasmid and its derivatives are valuable tools for genetic manipulation in L. fermentum.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Lactobacillus fermentum is a lactic acid bacterium found in animal and human digestive tracts.
- Antibiotic resistance in bacteria is a significant concern in public health.
- Plasmids are extrachromosomal DNA elements that can carry genes conferring advantageous traits, such as antibiotic resistance.
Purpose of the Study:
- To characterize a plasmid (pLEM3) conferring erythromycin resistance isolated from a porcine strain of L. fermentum.
- To assess the stability and utility of pLEM3 and its derivatives for genetic studies in L. fermentum.
Main Methods:
- Isolation and characterization of plasmid DNA from L. fermentum.
- Construction of deletion derivatives and cloning vectors.
- Determination of erythromycin resistance levels (MIC).
- Nucleotide sequencing and sequence analysis.
Main Results:
- A 5.7-kb plasmid, pLEM3, conferring high-level erythromycin resistance (MIC > 1 mg/ml) was isolated.
- pLEM3 demonstrated efficient establishment and segregation stability in L. fermentum.
- A deletion derivative (pLEM5) and a cloning vector (pLEM7) were constructed and found to be stable.
- Sequence analysis revealed pLEM3 belongs to the pC194 family of rolling circle plasmids, with the resistance gene showing high identity to erm from Tn1545.
Conclusions:
- The characterized plasmid pLEM3 is a stable and efficient tool for genetic manipulation in L. fermentum.
- The erythromycin resistance gene on pLEM3 has potential implications for understanding antibiotic resistance mechanisms.
- The development of pLEM7 provides a valuable cloning vector for further research in L. fermentum.