Arthrobacter ruber sp. nov., isolated from glacier ice

Area of Science:

• Microbiology
• Bacterial Taxonomy
• Extremophile Research

Background:

• Glaciers harbor unique microbial communities adapted to extreme environments.
• The genus Arthrobacter includes diverse bacteria found in various habitats.
• Characterizing novel microorganisms is crucial for understanding biodiversity and ecological roles.

Purpose of the Study:

• To isolate and characterize a novel bacterial strain from Tibetan glacier ice.
• To determine the taxonomic placement of the isolate using polyphasic methods.
• To propose a new species within the Arthrobacter genus.

Main Methods:

• Isolation of bacteria from glacier ice samples.
• Gram staining and basic physiological tests (catalase, oxidase).
• 16S rRNA gene sequencing for phylogenetic analysis.
• Multilocus sequence analysis (MLSA).
• Genomic analysis including Average Nucleotide Identity (ANI) and digital DNA-DNA hybridization (dDDH).
• Analysis of cellular fatty acids, polar lipids, and menaquinones.

Main Results:

• A Gram-positive strain, MDB1-42T, was isolated and exhibited optimal growth at 25-28°C and pH 7.0.
• Phylogenetic analysis based on 16S rRNA showed MDB1-42T is closely related to Arthrobacter agilis.
• MLSA, ANI, and dDDH values indicated significant genetic divergence from A. agilis, supporting a new species designation.
• Chemotaxonomic data (fatty acids, polar lipids, menaquinone) were consistent with the genus Arthrobacter.
• The G+C content of the genomic DNA was 69.0 mol%.

Conclusions:

• Strain MDB1-42T represents a distinct species within the genus Arthrobacter.
• The proposed novel species is named Arthrobacter ruber sp. nov.
• The type strain for this new species is MDB1-42T (=CGMCC 1.9772T=NBRC 113088T).
• This discovery contributes to the understanding of microbial diversity in glacial environments.