Serratia silvae sp. nov., Isolated from Forest Soil.

Area of Science:

• Microbiology
• Bacteriology
• Genomics
• Phylogenetics

Background:

• The genus Serratia comprises Gram-negative bacteria with diverse ecological roles.
• Accurate taxonomic classification is crucial for understanding microbial diversity and function.
• Previous studies have established genetic and phenotypic criteria for bacterial species delineation.

Purpose of the Study:

• To characterize a novel bacterial isolate from forest soil.
• To determine the taxonomic position of the isolate within the genus Serratia.
• To propose a new species designation based on comprehensive analyses.

Main Methods:

• Isolation and cultivation of the bacterial strain Arafor3^T from forest soil.
• 16S rRNA gene sequencing and multilocus sequence analysis (MLSA) using housekeeping genes (atpD, gyrB, infB, rpoB).
• Phylogenomic analysis, average nucleotide identity (ANI), and digital DNA-DNA hybridization (dDDH) comparisons.
• Phenotypic characterization including biochemical tests (urease, arginine dihydrolase) and chemotaxonomic analyses (fatty acid profiling, polar lipids, respiratory quinones).

Main Results:

• Strain Arafor3^T, a Gram-negative, oxidase-negative, catalase-positive rod, was isolated.
• Phylogenetic analyses placed Arafor3^T within the Serratia genus, closely related to Serratia fonticola.
• ANI (93.5%) and dDDH (55.7%) values were below species-level thresholds, supporting novelty.
• Distinct phenotypic characteristics, including negative urease and arginine dihydrolase activity, differentiated Arafor3^T from S. fonticola.

Conclusions:

• Strain Arafor3^T represents a distinct genomic and phenotypic entity within the Serratia genus.
• The data strongly support the classification of Arafor3^T as a new species.
• The proposed name for this novel species is Serratia silvae sp. nov., with strain Arafor3^T as the type strain.