Summary auto-generated
This study describes two novel species of Pseudoalteromonas, a genus of marine heterotrophic bacteria. Strain KMM 636T was isolated from the Australian sponge Fascaplysinopsis reticulata collected from the Coral Sea. This Gram-negative, rod-shaped bacterium with a single polar flagellum produces distinctive lemon-yellow chromopeptide pigments with cytotoxic and antibacterial properties. It requires 0.5-10% NaCl for growth, with optimum growth at 1-3% NaCl and 25-30°C. Additionally, the researchers reclassified strain NCIMB 2033, previously identified as Pseudoalteromonas aurantia, into a separate species based on polyphasic analysis. DNA-DNA hybridization experiments revealed genetic relatedness ranging from 19-35% between KMM 636T and related type strains, establishing them as distinct species. Phylogenetic analysis of 16S rRNA gene sequences confirmed both strains belong to the gamma-subclass of Proteobacteria within the Pseudoalteromonas genus. Based on phenotypic, chemotaxonomic, and genetic data, strain KMM 636T is proposed as Pseudoalteromonas maricaloris sp. nov., while NCIMB 2033 is reclassified as Pseudoalteromonas flavipulchra sp. nov.
Key findings
- A novel marine bacterium (P. maricaloris) was isolated from an Australian sponge and identified through polyphasic analysis combining phenotypic, chemotaxonomic, genetic, and phylogenetic methods.
- The new species produces unique lemon-yellow chromopeptide pigments with cytotoxic activity against sea urchin eggs and antibacterial activity against multiple bacterial species.
- DNA-DNA hybridization showed P. maricaloris and the reclassified P. flavipulchra are genetically distinct species with only 19-35% relatedness to related type strains.
- The bacterium requires 1-3% NaCl for optimal growth and grows at temperatures between 10-37°C, with optimum at 25-30°C, typical of marine Pseudoalteromonas species.
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Abstract
A marine, Gram-negative, aerobic bacterium that produced cytotoxic, lemon-yellow, chromopeptide pigments that inhibited the development of sea urchin eggs has been isolated from the Australian sponge Fascaplysinopsis reticulata Hentschel. The cells of the organism were rod-shaped with a single polar flagellum and they required NaCl for growth (0.5--10%) with optimum growth at 1--3% NaCl. The temperature for growth was 10--37 degrees C, with optimum growth at 25--30 degrees C. Growth occurred at pH values from 6.0 to 10.0, with optimum growth at pH 6.0--8.0. Major phospholipids were phosphatidylethanolamine, phosphatidylglycerol and lyso-phosphatidylethanolamine. Of 26 fatty acids with 11--19 carbon atoms that were detected, 16:1omega7, 16:0, 17:1omega8 and 18:1omega7 were predominant. The DNA G+C content was 38.9 mol%. All of these phenotypic and chemotaxonomic characters place the organism in the genus Pseudoalteromonas (Gauthier et al., 1995). These data are consistent with the phylogenetic analyses that confirmed that strain KMM 636(T) is a member of the Pseudoalteromonas cluster in the gamma-subclass of the Proteobacteria. DNA--DNA hybridization experiments revealed that the levels of relatedness between the DNA of the strain studied and DNAs of type strains of the species that clustered together (on the basis of 16S rDNA sequences) and [Pseudoalteromonas aurantia] NCIMB 2033 ranged from 19 to 35%, and that the DNA--DNA homology between [P. aurantia] NCIMB 2033 and other phylogenetically and/or phenotypically similar type strains ranged from 32 to 52%. According to the polyphasic evidence presented in this study, it is proposed that strain KMM 636(T) (=LMG 19692(T)=CIP 106859(T)) be classified as Pseudoalteromonas maricaloris sp. nov. and [P. aurantia] NCIMB 2033 be reclassified as Pseudoalteromonas flavipulchra NCIMB 2033(T) (=KMM 3630(T)=LMG 20361(T)) sp. nov.