Cloacibacterium caeni sp. nov., isolated from activated sludge

Area of Science:

• Microbiology
• Environmental Science
• Bacteriology

Background:

• Wastewater treatment plants are complex ecosystems harboring diverse microbial communities.
• Understanding bacterial diversity is crucial for optimizing wastewater treatment processes and identifying novel microorganisms.
• The genus Cloacibacterium comprises bacteria with known roles in environmental processes.

Purpose of the Study:

• To isolate and characterize a novel bacterial species from activated sludge.
• To determine the phylogenetic and chemotaxonomic properties of the isolate.
• To propose a new species within the genus Cloacibacterium.

Main Methods:

• Isolation and cultivation of bacteria from activated sludge.
• Gram staining, biochemical tests (oxidase, catalase), and pigment analysis.
• Physicochemical growth parameter determination (temperature, pH, salinity).
• Fatty acid analysis, respiratory quinone identification, and G+C content determination.
• Phylogenetic analysis using 16S rRNA gene sequences and DNA-DNA hybridization.

Main Results:

• A novel Gram-negative, facultatively anaerobic bacterium, designated B6T, was isolated.
• B6T is non-motile, oxidase- and catalase-positive, producing yellow carotenoid pigments.
• Optimal growth occurred at 37°C, pH 7.0, and without added NaCl.
• Major fatty acid was iso-C15:0, sole respiratory quinone was MK-6, and G+C content was 31.5 mol%.
• Phylogenetic analysis placed B6T within the genus Cloacibacterium, with low DNA-DNA relatedness to known species.
• B6T was formally proposed as Cloacibacterium caeni sp. nov., with strain B6T as the type strain.

Conclusions:

• B6T represents a distinct novel species, Cloacibacterium caeni sp. nov., within the genus Cloacibacterium.
• The phenotypic, chemotaxonomic, and molecular data support its classification as a new species.
• This discovery contributes to the understanding of bacterial diversity in engineered ecosystems like wastewater treatment plants.