Sphingobacterium puteale sp. nov., isolated from a deep subsurface aquifer

Area of Science:

• Microbiology
• Bacterial Taxonomy
• Environmental Microbiology

Background:

• Aquatic environments harbor diverse microbial communities.
• Deep aquifers represent underexplored habitats for novel bacterial discovery.
• The genus Sphingobacterium comprises Gram-negative bacteria with various environmental roles.

Purpose of the Study:

• To isolate and characterize a novel bacterial strain from a deep aquifer.
• To determine the taxonomic affiliation of the novel strain using phylogenetic and chemotaxonomic analyses.
• To propose a new species within the genus Sphingobacterium.

Main Methods:

• Isolation of bacterial strain M05W1-28^T from a 400m deep aquifer.
• Morphological, physiological, and biochemical characterization.
• Phylogenetic analysis based on 16S rRNA gene sequencing.
• Chemotaxonomic analysis including fatty acid and polar lipid profiling.
• Genomic analysis including G+C content, Average Nucleotide Identity (ANI), and digital DNA-DNA hybridization (dDDH).

Main Results:

• Strain M05W1-28^T is a rod-shaped, non-motile, aerobic, Gram-negative bacterium.
• Optimal growth at pH 7.0, 28°C, and 0% NaCl.
• Major fatty acids: summed feature 3 and iso-C15:0; major polar lipids: phosphatidylethanolamine, glycolipids, phosphoglycolipids, phospholipids.
• 16S rRNA gene sequence similarity indicated affiliation with the genus Sphingobacterium.
• ANI and dDDH values confirmed its distinction from known Sphingobacterium species.
• Genomic G+C content was 40.7%.

Conclusions:

• Strain M05W1-28^T represents a novel species within the genus Sphingobacterium.
• The proposed name for the novel species is Sphingobacterium puteale sp. nov.
• This discovery highlights the microbial diversity present in deep aquifer ecosystems.