Acinetobacter sedimenti sp. nov., isolated from beach sediment.

Area of Science:

• Microbiology
• Bacteriology
• Genomics

Background:

• The genus Acinetobacter comprises diverse bacteria, including opportunistic pathogens and environmental isolates.
• Understanding bacterial diversity in marine environments is crucial for ecological and biotechnological applications.

Purpose of the Study:

• To isolate and characterize a novel bacterial strain from beach sediment.
• To determine the phylogenetic and taxonomic position of the novel isolate within the Acinetobacter genus.
• To propose a new species designation based on comprehensive genotypic and phenotypic data.

Main Methods:

• Isolation and cultivation of bacteria from Zhairuo Island beach sediment.
• Physicochemical characterization including optimal growth conditions (pH, salinity, temperature).
• Whole-genome sequencing, core genome phylogenetic analysis, average nucleotide identity (ANI), and digital DNA-DNA hybridization (dDDH) calculations.
• Fatty acid analysis, respiratory quinone determination, and polar lipid profiling.
• Biochemical tests for substrate assimilation and utilization.

Main Results:

• A Gram-negative, aerobic, non-motile bacillus, strain A3.8^T, was isolated.
• Strain A3.8^T demonstrated specific growth ranges: pH 6.0-9.0, 0-4.5% NaCl, 10-35 °C.
• Phylogenetic analysis placed A3.8^T as a distinct lineage within Acinetobacter, with low ANI (<83.66%) and dDDH (<28.80%) values compared to related species.
• Unique metabolic profile, including inability to assimilate dl-lactate and weak utilization of certain amino acids and organic acids, differentiates it from known Acinetobacter species.

Conclusions:

• Strain A3.8^T represents a novel species within the genus Acinetobacter.
• The proposed name for this new species is *Acinetobacter sedimenti* sp. nov.
• The type strain is A3.8^T (=MCCC 1K07161^T=LMG 32568^T).