Thalassomonas loyana sp. nov., a causative agent of the white plague-like disease of corals on the Eilat coral reef

Researchers identified a novel bacterial species, Thalassomonas loyana, isolated from diseased coral (Favia favus) collected from the Eilat coral reef in the Red Sea. This gram-negative, motile rod-shaped bacterium with a single polar flagellum was the causative agent of white plague-like disease in coral samples and could reproduce the disease in controlled aquarium experiments. Through 16S rRNA gene sequencing and phenotypic analysis, the strain CBMAI 722T was classified within the family Colwelliaceae, with Thalassomonas ganghwensis as its nearest relative at 95% sequence similarity. T. loyana differs from other Thalassomonas species by lacking oxidase activity, producing alginase and amylase, utilizing cellobiose and L-arginine, and possessing a DNA G+C content of 39.3 mol%. The bacterium grew in synthetic seawater without organic supplements and displayed specific fatty acid profiles distinguishing it from related species. This discovery represents the first documented association of a Colwelliaceae family member with coral white plague-like disease, highlighting bacteria's emerging role in coral reef infections alongside other environmental stressors threatening global coral ecosystems.

Key findings

• Thalassomonas loyana sp. nov. is a novel bacterial species isolated from diseased coral in the Eilat reef that causes white plague-like disease
• The bacterium belongs to family Colwelliaceae and differs from related Thalassomonas species by lacking oxidase activity but producing alginase
• T. loyana exhibits a DNA G+C content of 39.3 mol% and displays distinctive fatty acid profiles and carbon source utilization patterns
• This is the first report linking a Colwelliaceae family member to coral white plague-like disease