Pseudomonas haemolytica sp. nov., isolated from raw milk and skimmed milk concentrate

Area of Science:

• Microbiology
• Genomics
• Dairy Science

Background:

• The genus *Pseudomonas* comprises diverse bacteria found in various environments, including dairy products.
• Identification and characterization of novel species are crucial for understanding microbial ecosystems and potential applications.

Purpose of the Study:

• To identify and characterize a previously unknown *Pseudomonas* species isolated from raw cow's milk and skimmed milk concentrate.
• To establish the taxonomic and phylogenetic position of the novel isolates within the *Pseudomonas* genus.

Main Methods:

• 16S rRNA and *rpoD* gene sequencing for initial identification.
• Multilocus sequence analysis (MLSA) and average nucleotide identity (ANIm) using draft genome sequences.
• Phenotypic characterization including growth conditions, biochemical tests, and hemolysis assays.
• Analysis of polar lipids, quinones, and fatty acid profiles.

Main Results:

• Two strains, WS 5063^T and WS 5067, were identified as a novel *Pseudomonas* species based on phylogenetic analyses.
• The novel species is most closely related to *Pseudomonas synxantha* with an ANIm of 91.4%.
• The isolates are aerobic, motile rods, positive for catalase and oxidase, exhibiting strong β-hemolysis and specific growth ranges (4-34°C, pH 5.5-8.0).
• Major polar lipids included phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol; the dominant quinone was Q-9.
• Fatty acid profiles were typical for *Pseudomonas*, with C_16:0 as the major component.

Conclusions:

• The two isolates represent a novel species, *Pseudomonas haemolytica* sp. nov.
• The type strain is WS 5063^T (=DSM 108987^T=LMG 31232^T).
• This discovery contributes to the taxonomic diversity of the *Pseudomonas* genus in dairy environments.