Summary auto-generated
Researchers isolated eleven non-pigmented, Gram-negative bacterial strains from the thallus of the brown alga Fucus evanescens collected from the Kurile Islands in the Pacific Ocean. These marine bacteria were rod-shaped with single polar flagella and exhibited high genetic relatedness (91%) to each other. The strains belonged to the genus Pseudoalteromonas within the γ-subclass of Proteobacteria, based on 16S rDNA analysis. They displayed DNA G-C content of 42.9-43.3 mol% and showed only 27-54% genetic relatedness to other known Pseudoalteromonas species. The bacteria demonstrated diverse enzymatic activities including bacteriolytic, proteolytic, and haemolytic properties, and synthesized multiple glycoside hydrolases (fucoidanases, laminaranases, alginases, agarases, and others) that degrade algal polysaccharides. Phenotypically, the strains were halophilic, requiring 0.5-15% NaCl for growth, with optimal growth at 28-30°C and pH 7.5-8.0. Based on genetic evidence and phenotypic characteristics, the researchers designated these isolates as a novel species, Pseudoalteromonas issachenkonii sp. nov., with type strain KMM 3549T.
Key findings
- Eleven conspecific bacterial strains isolated from degraded brown alga tissue represent a new species, Pseudoalteromonas issachenkonii, based on 91% DNA-DNA hybridization between isolates and only 27-54% relatedness to other Pseudoalteromonas species
- P. issachenkonii produces multiple glycoside hydrolases including fucoidanases, laminaranases, and alginases that enable degradation of algal polysaccharides and thallus material
- The novel species exhibits halophilic, bacteriolytic, and haemolytic properties, grows optimally at 28-30°C and pH 7.5-8.0, and tolerates NaCl concentrations up to 15%
- 16S rDNA sequence analysis confirmed the bacteria belong to the γ-subclass of Proteobacteria and form a robust clade with P. tetraodonis within the Pseudoalteromonas genus
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Abstract
Eleven non-pigmented strains of Gram-negative, aerobic, marine bacteria with polar flagella were isolated from the thallus of the brown alga Fucus evanescens collected in the Kraternaya Bight of the Kurile Islands in the Pacific Ocean. These organisms were conspecific and exhibited high levels of genetic relatedness (up to 91%). The G+C contents of the DNAs of these strains were 42.9--43.3 mol%. These halophilic bacteria had bacteriolytic, proteolytic and haemolytic activities and degraded algal polysaccharides, synthesizing a number of glycoside hydrolases (fucoidanases, laminaranases, alginases, agarases, pullulanases, beta-glucosidases, beta-galactosidases, beta-N-acetylglucosaminidases and beta-xylosidases). By 16S rDNA analysis, the bacteria were shown to belong to the genus Pseudoalteromonas, a member of the gamma-subclass of the Proteobacteria. DNA from the strains isolated from the brown alga showed 27--54% genetic relatedness with respect to DNAs of other type strains of the genus Pseudoalteromonas. The phenotypic characteristics, together with the genetic evidence, indicate that this group of epiphytic bacteria represents a distinct species, Pseudoalteromonas issachenkonii sp. nov., for which the type strain is KMM 3549(T) (=LMG 19697(T)=CIP 106858(T)).