Kordia algicida gen. nov., sp. nov., an algicidal bacterium isolated from red tide

Researchers isolated a novel bacterium designated strain OT-1T from seawater during a red tide outbreak in Masan Bay, Korea. This bacterium demonstrated algicidal activity, killing and lysing multiple marine microalgae species including Skeletonema costatum, Thalassiosira sp., Heterosigma akashiwo, and Cochlodinium polykrikoides. Phylogenetic analysis of 16S rRNA gene sequences revealed the isolate formed a distinct lineage within the family Flavobacteriaceae, showing less than 93% sequence similarity to any previously named species. The bacterium is Gram-negative, yellow-pigmented, non-motile, strictly aerobic, and requires sodium, calcium, and magnesium ions for growth. Chemotaxonomic analysis identified characteristic branched fatty acids, menaquinone 6 as the respiratory quinone, and a DNA G+C content of 34 mol%. Based on comprehensive polyphasic evidence including phylogenetic, morphological, physiological, and biochemical characteristics, the authors propose this isolate as a new genus and species: Kordia algicida gen. nov., sp. nov. This discovery is significant because algicidal bacteria could potentially be useful in controlling harmful algal blooms in coastal waters.

Key findings

• Strain OT-1T is a novel bacterium with algicidal activity capable of killing multiple harmful microalgal species responsible for red tides
• Phylogenetic analysis based on 16S rRNA sequences showed <93% similarity to known species, establishing it as a new genus within Flavobacteriaceae
• The bacterium requires sea salt ions (Na+, Ca2+, Mg2+) for growth and grows optimally at 3% NaCl, 30°C, and pH 7-8
• Chemotaxonomic characteristics including iso-branched fatty acids, menaquinone 6, and 34 mol% DNA G+C content support placement in family Flavobacteriaceae
• The authors propose the name Kordia algicida gen. nov., sp. nov., with potential applications for controlling harmful algal blooms