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Unusual genome complexity in Lactobacillus salivarius JCM1046
Emma J Raftis, Brian M Forde, Marcus J Claesson
1School of Microbiology University College Cork, Cork, Ireland. pwotoole@ucc.ie.
BMC Genomics
|September 10, 2014
Summary
This study reveals the complex genome of Lactobacillus salivarius JCM1046, identifying novel plasmids and a conjugative transposon. This is crucial for understanding probiotic strain selection and antibiotic resistance gene spread.
Area of Science:
- Microbiology
- Genomics
- Probiotics
Background:
- Lactobacillus salivarius is widely used as a probiotic.
- Antibiotic resistance gene dissemination is a concern in probiotic bacteria.
- L. salivarius strains possess complex genomes, often including megaplasmids.
Purpose of the Study:
- To investigate the complex genome structure of the porcine Lactobacillus salivarius JCM1046 isolate.
- To experimentally validate the topology and characteristics of its plasmids.
Main Methods:
- Whole-genome sequencing of L. salivarius JCM1046.
- Experimental validation of plasmid topology.
- Bioinformatic analysis of identified replicons and genes.
Main Results:
- L. salivarius JCM1046 has a 1.83 Mb chromosome and four plasmids (20% of genome).
- Identified plasmids include a megaplasmid (pMP1046A), a putative chromid (pMP1046B), a linear plasmid (pLMP1046), and a plasmid with a conjugative transposon (pCTN1046).
- The conjugative transposon (Tn6224) on pCTN1046 carries the tetracycline resistance gene tetM.
Conclusions:
- The complex genome architecture of L. salivarius JCM1046 was resolved through experimental validation.
- High-coverage draft genome sequencing alone is insufficient to reveal such complexity.
- Identifying mobile genetic elements like Tn6224 is critical for selecting safe and effective probiotic strains.
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