The Biogeochemistry of Marine Polysaccharides: Sources, Inventories, and Bacterial Drivers of the Carbohydrate Cycle

Abstract

Polysaccharides are major components of macroalgal and phytoplankton biomass and constitute a large fraction of the organic matter produced and degraded in the ocean. Until recently, however, our knowledge of marine polysaccharides was limited due to their great structural complexity, the correspondingly complicated enzymatic machinery used by microbial communities to degrade them, and a lack of readily applied means to isolate and characterize polysaccharides in detail. Advances in carbohydrate chemistry, bioinformatics, molecular ecology, and microbiology have led to new insights into the structures of polysaccharides, the means by which they are degraded by bacteria, and the ecology of polysaccharide production and decomposition. Here, we survey current knowledge, discuss recent advances, and present a new conceptual model linking polysaccharide structural complexity and abundance to microbially driven mechanisms of polysaccharide processing. We conclude by highlighting specific future research foci that will shed light on this central but poorly characterized component of the marine carbon cycle. Expected final online publication date for the Annual Review of Marine Science, Volume 13 is January 3, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Polysaccharide degradation by the Bacteroidetes: mechanisms and nomenclature

“…The proficiency of the Bacteroidetes in polysaccharide degradation, and the view of PULs as synergistic gene clusters whose CAZyme functions essentially describe the structure of the target polysaccharide, has also enabled estimations of the global diversity of glycans in Nature in bioinformatic meta-studies (Lapébie et al, 2019). Specifically, the inventory of PULs from marine bacteria is helping to generate an increasingly nuanced view of the structure and abundance of marine polysaccharides (Becker et al, 2017;Becker et al, 2020;Arnosti et al, 2021). Furthermore, the convenient PUL clustering of synergistic CAZyme genes targeting a particular polysaccharide has facilitated the discovery of new CAZyme functions, which has great implications for both fundamental understanding of microorganisms and enzymes, but also for industry aiming to develop more sustainable methods for conversion of renewable biomass.…”

Potential and expression of carbohydrate utilization by marine fungi in the global ocean

“…To fill that critical gap in knowledge, we performed a global-ocean multi-omics analysis on the presence (metagenomes-metaG) and expression (metatranscriptomes-metaT) of carbohydrate active enzymes (CAZymes). We focused on CAZymes because (i) they are the main group of enzymes involved in cleaving carbohydrates which together with proteins are the major macromolecules in organisms and in marine snow [ 3 ], (ii) we recently found CAZymes to be key enzymes in the degradation of organic matter by pelagic heterotrophic prokaryotes in the ocean [ 2 , 40 ], and (iii) a large number of published microbial CAZyme gene profiles/catalogs are available from various environments [ 2 , 14 , 21 , 28 , 40 ].…”

CAZymes in Maribacter dokdonensis 62–1 From the Patagonian Shelf: Genomics and Physiology Compared to Related Flavobacteria and a Co-occurring Alteromonas Strain

“…Continental shelves are productive marine systems, where photosynthesis by pelagic phytoplankton and benthic macroalgae yields considerable amounts of organic matter. Polysaccharides constitute a major fraction of the algae-derived organic matter, with important roles in nutrient cycles and microbial metabolism (Hehemann et al, 2014;Arnosti et al, 2021). Consequently, diverse bacteria are specialized for the degradation of algal polysaccharides, colonization of algal surfaces and other types of biological interactions (van der Loos et al, 2019;Ferrer-González et al, 2020;Wolter et al, 2021).…”