Summary auto-generated
Researchers isolated a novel bacterium from a fish-processing plant drain that possesses unusual properties combining cold tolerance and alkaliphilicity. Named Dietzia psychralcaliphila, this Gram-positive rod grows on n-alkanes as its sole carbon source at low temperatures (5–30°C) across a wide pH range (7–10). The bacterium was identified through multiple analytical approaches: 16S rRNA gene sequencing showed 96.1–96.8% similarity to existing Dietzia species, while DNA–DNA hybridization revealed only 38.4–49.7% relatedness, confirming it as a distinct species. Chemotaxonomic analysis revealed characteristics typical of Dietzia, including meso-diaminopimelic acid in the cell wall, mycolic acids, and MK-8(H₂) as the major quinone. The isolate utilizes various saturated hydrocarbons (n-tridecane through n-tetracosane and pristane) but not shorter or longer chain alkanes, or polycyclic aromatics. This is the first reported facultatively psychrophilic alkaliphile capable of utilizing n-alkanes on defined medium, with potential applications for bioremediation of oil-contaminated environments at low temperatures.
Key findings
- Dietzia psychralcaliphila is a novel psychrophilic alkaliphile isolated from a fish-processing plant drain that grows on n-alkanes as sole carbon source at 5–30°C and pH 7–10
- 16S rRNA analysis shows 96.1–96.8% similarity to known Dietzia species, but DNA–DNA hybridization indicates only 38.4–49.7% relatedness, confirming novel species status
- The bacterium utilizes a specific range of n-alkanes (C13–C28 and pristane) but cannot degrade shorter chains (C12), longer chains (C32), or polycyclic aromatic hydrocarbons
- Cell wall contains meso-diaminopimelic acid, arabinose, galactose, and short-chain mycolic acids (34–39 carbons), consistent with Dietzia genus classification
- The organism's ability to degrade hydrocarbons across wide pH and low-temperature ranges suggests potential for bioremediation of oil-contaminated soil and water in cold environments
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Abstract
A novel, facultatively psychrophilic alkaliphile that grows on a chemically defined medium containing n-alkanes as the sole carbon source was isolated from a drain of a fish product-processing plant. The isolate was an aerobic, non-motile, Gram-positive bacterium. The bacterium was catalase-positive and oxidase-negative. The cell wall contained meso-diaminopimelic acid, arabinose and galactose; the glycan moiety of the cell wall contained acetyl residues. The G+C content of the DNA was 69.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate was closely related to members of the genus Dietzia (96.1--96.8% similarity). Comparisons of phenotypic and chemotaxonomic characteristics between the isolate and the two known Dietzia species showed that they were very similar. However, the isolate differed from the two known Dietzia species in growth temperature range and certain physiological characteristics. DNA--DNA hybridization revealed that the isolate had 38.4 and 49.7% relatedness, respectively, to Dietzia maris and Dietzia natronolimnaea. On the basis of the physiological and biochemical characteristics, the phylogenetic position as determined by 16S rRNA gene analysis and DNA--DNA relatedness, it is concluded that the isolate should be designated as a novel species, for which the name Dietzia psychralcaliphila sp. nov. is proposed. The type strain is ILA-1(T) (=JCM 10987(T)=IAM14896(T)=NCIMB 13777(T)).