Comparative genomic analysis of cyanobacteria as amphibian food sources: insights into high-temperature tolerance potential

Abstract Hot-springs represent one of the most accessible yet extreme environments on the Earth’s surface. We isolated and characterized two novel cyanobacterial strains of the genus Leptolyngbya, L . sp. Akita and L . sp. Seranma from geothermal hot-springs in Japan. These strains showed distinct morphological features; L . sp. Akita exhibited linear filamentous structures and blue-green color when cultured under white light, whereas L . sp. Seranma exhibited loosely coiled structures and a brown color under the same conditions. Whole-genome sequencing and comprehensive genomic analyses of their genomes identified the acquisition of gene clusters related to metabolic processes, which may be associated with strain-specific phenotypes. In addition, intestinal metagenomic analysis of tadpoles ( Buergeria buergeri and B. japonica ) sympatrically living with these strains in the hot-springs suggested that the tadpoles utilized these Leptolyngbya as temporal or regular foods in high-temperature environments. These findings provide insights into the ecological significance of these cyanobacteria in extreme environments and their potential applications in biotechnology and the ecological conservation of primary consumers, including amphibians.