The Structure and Function of the Sargassum fusiforme Microbiome under Different Conditions

Brown macroalgae, a key component of the vegetated coastal ecosystems, can sequester a large amount of CO2, which is mainly converted to polysaccharides. These polysaccharides confer complex structures and are difficult to be degraded by microbial communities. On the surface of brown macroalgae in which bacteria lived, the diversity and encoded enzymes of these bacteria involved in carbon cycling remain largely unknown. In this study, we used metagenomic sequencing to survey bacteria communities associated with the Sargassum fusiforme under different conditions and investigated the structure and function of these bacteria. A total of 5308 species were discovered in all 15 samples from different conditions. Most of these species belonged to the phylum Proteobacteria. Many S. fusiforme-associated bacteria could decompose algal polysaccharides under different conditions. Our method could enhance the ability to understand the microbiome community. To the best of our knowledge, this is the first report regarding metagenomics in S. fusiforme. The co-occurrence network provides insights into the relationship of the polysaccharide degradation enzymes (PDEs). These data provide a reference for the cultivation of S. fusiforme and the understanding of the marine carbon cycle.