Summary auto-generated
This study reclassified two previously misidentified marine bacteria that decompose algal polysaccharides. Researchers examined seven bacterial strains isolated from seaweeds, including five newly isolated strains and two previously described strains initially classified as Pseudomonas species. Using DNA-DNA hybridization, chemical analysis (G+C content and ubiquinone composition), and phenotypic characterization, they determined that six agar-decomposing strains belonged to a single species, designated Alteromonas atlantica. These strains showed DNA homology values above 82% and phenotypic similarity of 79-96% based on carbon substrate assimilation tests. A separate carrageenan-decomposing strain was designated Alteromonas carrageenovora. Both species were gram-negative, aerobic rods with polar flagella, possessed ubiquinone-8 as their major respiratory quinone, and had G+C contents of 39.5-41.7 mol%. The two species differed in their ability to hydrolyze agar and carrageenan, utilize certain carbon sources, and assimilate specific compounds. Type strains were designated for both newly named species, and detailed phenotypic descriptions were provided to differentiate them from other known Alteromonas species.
Key findings
- Six previously uncharacterized and misidentified marine bacterial strains were reclassified as Alteromonas atlantica based on DNA-DNA hybridization (>82% homology) and phenotypic similarity tests
- A carrageenan-decomposing strain previously classified as Pseudomonas carrageenovora was reclassified as Alteromonas carrageenovora and confirmed as a distinct species with unique enzymatic and metabolic properties
- Both A. atlantica and A. carrageenovora possess ubiquinone-8 as their major respiratory quinone and G+C content of 39.5-41.7 mol%, confirming their assignment to genus Alteromonas
- A. atlantica can hydrolyze multiple algal polysaccharides including agar, alginate, and carrageenan, while A. carrageenovora specifically degrades carrageenan
- Differential phenotypic characteristics including carbon source assimilation profiles and enzymatic activities distinguish these two species from each other and from other known nonpigmented Alteromonas species
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Abstract
We studied seven strains of aerobic, marine, polarly flagellated bacteria which decompose alginate, agar, and carrageenan. The major respiratory quinone of these strains was ubiquinone-8. The G+C content of their DNA was 39.5 to 41.7 mol%. "Pseudomonas atlantica" IAM 12927 and the conspecific five isolates were concluded to constitute a single species distinguished from the other nonpigmented Alteromonas species by DNA-DNA hybridization (homology values of more than 82%) and phenotypic similarity (similarity coefficients, based on assimilation of 145 carbon compounds, were 79 to 96%). "Pseudomonas carrageenovora" IAM 12662, the sole extant strain, was distinct from "P. atlantica" and other Alteromonas species in DNA-DNA hybridization and phenotypic features. Taxonomic affinity to Alteromonas espejiana was indicated by DNA-DNA hybridization with "P. atlantica" IAM 12927 and the five conspecific isolates (39 to 55%) and with "P. carrageenovora" IAM 12662 (43 to 45%). Phenotypically, higher similarity values (79 to 89%) for assimilation of 145 carbon compounds were shared between A. espejiana IAM 12927T and the six conspecific strains, including "P. atlantica" IAM 12927. Alteromonas atlantica sp. nov. (type strain, IAM 12927, =ATCC 19262, =NCIMB 301) and Alteromonas carrageenovora (type strain, IAM 12662, =IFO 12985, =ATCC 43555, =NCIMB 302) are proposed for "P. atlantica" IAM 12927 and the conspecific five isolates and "P. carrageenovora" IAM 12662, respectively. A set of phenotypic features which differentiate the two Alteromonas species is described.