Paracoccus fontiphilus sp. nov., isolated from a freshwater spring

Area of Science:

• Microbiology
• Bacteriology
• Phylogenetics

Background:

• The genus Paracoccus is a diverse group of Gram-negative bacteria found in various environments.
• Understanding bacterial diversity is crucial for ecological and biotechnological applications.
• Previous studies have identified several Paracoccus species, but exploration of freshwater environments continues to reveal novel taxa.

Purpose of the Study:

• To characterize a novel bacterial isolate, strain MVW-1^T, from a freshwater spring in Taiwan.
• To determine the taxonomic position of strain MVW-1^T using a polyphasic approach.
• To propose a new species within the genus Paracoccus based on phenotypic and genotypic data.

Main Methods:

• Polyphasic taxonomy, including 16S rRNA gene sequencing for phylogenetic analysis.
• Determination of phenotypic characteristics: Gram staining, cell shape, motility, colony color, optimal growth conditions (temperature, pH, salinity).
• Analysis of chemotaxonomic markers: major fatty acids, polar lipids, polyamines, isoprenoid quinones, and DNA G+C content.
• DNA-DNA hybridization to assess genetic relatedness with closely related species.

Main Results:

• Phylogenetic analysis placed strain MVW-1^T within the genus Paracoccus, with highest 16S rRNA gene similarity to P. caeni MJ17^T (97.6%).
• Phenotypic characterization revealed Gram-negative, aerobic, non-motile rods accumulating poly-β-hydroxybutyrate, forming light orange colonies.
• Optimal growth occurred at 20-25°C, pH 6-7, and 0-3% NaCl. Major fatty acid was C18:1ω7c. DNA G+C content was 63.4 mol%.
• DNA-DNA relatedness to closely related species was below 35%, supporting its distinctiveness.
• The polar lipid profile included PG, PE, PC, DPG, and unidentified lipids. Predominant polyamines were spermidine, putrescine, and cadaverine. The sole isoprenoid quinone was Q-10.

Conclusions:

• Strain MVW-1^T represents a novel species within the genus Paracoccus.
• The proposed name for this new species is Paracoccus fontiphilus sp. nov.
• The type strain is MVW-1^T (=BCRC 80974^T=LMG 29554^T=KCTC 52239^T).