Biocatalytic quantification of α‐glucan in marine particulate organic matter

Abstract

Marine algae drive the marine carbon cycle, converting carbon dioxide into organic material. A major component of this produced biomass is a variety of glycans. Marine α-glucans include a range of storage glycans from red and green algae, bacteria, fungi, and animals. Although these compounds are likely to account for a high amount of the carbon stored in the oceans they have not been quantified in marine samples so far. Here we present a method to extract and quantify α-glucans (and compare it with the β-glucan laminarin) in particulate organic matter from algal cultures and environmental samples using sequential physicochemical extraction and enzymes as α-glucan-specific probes. This enzymatic assay is more specific and less susceptible to side reactions than chemical hydrolysis. Using HPAEC-PAD to detect the hydrolysis products allows for a glycan quantification in particulate marine samples down to a concentration of ≈2 µg/L. We measured glucans in three cultured microalgae as well as in marine particulate organic matter from the North Sea and western North Atlantic Ocean. While the β-glucan laminarin from diatoms and brown algae is an essential component of marine carbon turnover, our results further indicate the significant contribution of starch-like α-glucans to marine particulate organic matter. Henceforth, the combination of glycan-linkage-specific enzymes and chromatographic hydrolysis product detection can provide a powerful tool in the exploration of marine glycans and their role in the global carbon cycle.

Automated Synthesis of Algal Fucoidan Oligosaccharides

“…The microbial degradation of fucoidan involves hundreds of enzymes. , Enhancing our understanding of fucoidan-active CAZymes and their substrate tolerances will advance our mechanistic understanding of how certain fucoidan structures resist degradation, leading to carbon sequestration. Furthermore, characterized enzymes can serve as biocatalytic assays to assist in the detection and quantification of fucoidan in the environment. , …”

“…Furthermore, characterized enzymes can serve as biocatalytic assays to assist in the detection and quantification of fucoidan in the environment. 80,81 CAZymes of the glycoside hydrolase family 107 (GH107) cleave in midchain glycosidic bonds of algal fucoidans. 82 All current GH107 members are endo-fucoidanases targeting either α-1,3 or α-1,4 fucosyl linkages.…”

Alpha-glucans from bacterial necromass indicate an intra-population loop within the marine carbon cycle

“…Polysaccharide extraction was performed from 3 and 0.2 μm bloom membrane filters of the spring bloom samples and from bacterial single-cultures. Analysis of the extracts was carried out as described 93 . In short, membrane filters were cut into small pieces and extracted using hot ddH 2 O with sonication treatment and debris was removed via centrifugation (4500 × g , 15 min).…”

Architecture, Function, Regulation, and Evolution of α-Glucans Metabolic Enzymes in Prokaryotes

“…This is well represented by cellulose, the most abundant biomolecule in the biosphere, and the main component of the plant cell wall (Figure A,B). β-Glucans can play other functions, including (i) cellulose as a fibrous structural component of bacterial biofilms, it forms a mechanically strong hydrogel with high water adsorption capabilities, (ii) cyclic β-glucans act as messengers in plant-microbe interactions, (iii) internal and external energy storages . The fungal cell wall is composed of a polysaccharide-based three-dimensional network that is continuously adapting to growth and environmental conditions and is essential for cell survival (1).…”