Summary auto-generated
Researchers identified and characterized a marine bacterium isolated from red-spotted culture beds of Laminaria japonica (kelp), which causes red spot disease of the seaweed's seeds. Five bacterial isolates were aerobic, polarly flagellated Gram-negative rods that produced a prodigiosin-like red pigment and exhibited unique bacteriolytic activity against both Gram-positive and Gram-negative bacteria—a trait never before observed in Alteromonas or related species. Phenotypic characteristics resembled Pseudoalteromonas rubra but differed in 10 key traits, including bacteriolytic activity, growth temperature preferences, and carbohydrate utilization patterns. DNA-DNA hybridization experiments and 16S rRNA gene sequence analysis confirmed the isolates represented a distinct species separate from other Pseudoalteromonas and Alteromonas species, with DNA G+C content of 44-46 mol%. The researchers propose the name Pseudoalteromonas bacteriolytica sp. nov. for this new species, with IAM 14595T designated as the type strain. The bacterium's bacteriolytic activity likely enables survival in nutrient-poor marine environments.
Key findings
- Five bacterial isolates from diseased Laminaria japonica kelp represent a novel species, Pseudoalteromonas bacteriolytica, characterized by unique bacteriolytic activity against diverse bacterial species never before reported in this genus.
- DNA-DNA hybridization and 16S rRNA phylogenetic analysis confirmed the isolates form a distinct clade within Pseudoalteromonas, phylogenetically distant from P. rubra and other related species.
- The new species differs from P. rubra in 10 phenotypic traits including bacteriolytic activity, growth at 37°C, organic growth factor requirements, and utilization of various carbon sources.
- G+C content of 44-46 mol% and low 16S rRNA sequence homology (87.7-90.3%) with other Pseudoalteromonas species support recognition as a separate species.
- The bacteriolytic enzymes produced by P. bacteriolytica represent an ecological adaptation for survival in oligotrophic (nutrient-poor) marine environments.
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Abstract
An aerobic, polarly flagellated marine bacterium that produces a prodigiosinlike pigment was isolated from the red-spotted culture beds of Laminaria japonica. Five isolates had unique bacteriolytic activity for both Gram-positive and -negative bacteria, which had never been observed among Alteromonas or related species. The isolates were identified as the causative agent of red spot disease of L. japonica seeds. The phenotypic features of the isolates were similar to these of Pseudoalteromonas rubra ATCC 29570T, but they could be differentiated using 10 traits (growth at 37°C, requirement for organic growth factors, bacteriolytic activity, utilization of sucrose, N-acetylglucosamine, fumarate, succinate, D-galactose, L-proline and acetate). The G+C content of DNAs from the isolates was 44–46 mol%. The isolates constitute a new species, distinct from the other Alteromonas and Pseudoalteromonas species, as shown by DNA-DNA hybridization experiments and phylogenetic clustering of 16S rRNA gene sequences, for which the name Pseudoalteromonas bacteriolytica sp. nov. (type strain = IAM 14595T) is proposed. A set of phenotypic features which differentiate this new species from closely related Pseudoalteromonas and Alteromonas species is provided.