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

Abstract

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.

Functional stability despite high taxonomic turnover characterizes the Ulva microbiome across a 2,000 km salinity gradient

“…4). Similarly, proline biosynthesis at low salinity can be conducted by Alteraurantiacibacter and Rubripirellula (5-8 PSU), at medium salinity by Litorimonas A (8-18 PSU), and was gradually taken over by Neomegalonema (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and Leucothrix and Litorimonas at high salinity (30-36 PSU). In addition, most MAGs shared a set of core genes that are necessary for essential functions, including nucleotide metabolism, fatty acid biosynthesis, energy metabolism (F-type ATPases, succinate dehydrogenases, etc.…”

“…4 gives a complete overview of the presence or absence of KEGG modules in the metagenomic assembled genomes of 26 taxa that are characteristic to a specific salinity 15 region (horohalinicum 5-8 PSU, mesohaline 8-18 PSU, polyhaline 18-30 PSU, or euhaline 30-36 PSU). Pantothenate (vitamin B 5 ), for example, can be produced at low to medium salinity (5-18 PSU) by an unknown Saprospiraceae (MAG591), but at medium to high salinity (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36) this function in the community was taken over by Robiginitomaculum and another unknown Saprospiraceae (MAG149) (Fig. 4).…”

“…Metagenomic functional profiling in, for example, Sargassum spp. 18,19 , Pyropia haitanensis 20 , and Nereocystis luetkeana 21 highlighted the importance of the bacterial biofilm in terms of vitamin production, polysaccharide degradation, and nutrient cycling. However, these studies were based on a relatively small number of replicates (between 3-7 samples) and therefore do not capture differences across environments.…”

Polysaccharides from the Sargassum and Brown Algae Genus: Extraction, Purification, and Their Potential Therapeutic Applications

“…The large extensions of the macroalgae can capture large amounts of CO 2 , most of which are converted to polysaccharides, which play a key role in carbon cycling [4]. The most important polysaccharides are mainly laminarins, alginates, carrageenan, and fucoidans [5,6].…”