Functional genomics analysis reveals the biosynthesis pathways of important cellular components (alginate and fucoidan) of Saccharina

Phenylboronic Acid-Functionalized Micelles Dual-Targeting Boronic Acid Transporter and Polysaccharides for siRNA Delivery into Brown Algae

Brown algae play essential roles ecologically, practically, and evolutionarily because they maintain coastal areas, capture carbon dioxide, and produce valuable chemicals such as therapeutic drugs. To unlock their full potential, understanding the unique molecular biology of brown algae is imperative. Genetic engineering tools that regulate homeostasis in brown algae are essential for determining their biological mechanisms in detail. However, few methodologies have been developed to control gene expression due to the robust structural barriers of brown algae. To address this issue, we designed peptide-based, small interfering RNA (siRNA)-loaded micelles decorated with phenylboronic acid (PBA) ligands. The PBA ligands facilitated the cellular uptake of the micelles into a model brown alga, Ectocarpus siliculosus (E. Siliculosus), through chemical interaction with polysaccharides in the cell wall and biological recognition by boronic acid transporters on the plasma membrane. The micelles, featuring "kill two birds with one stone" ligands, effectively induced gene silencing related to auxin biosynthesis. As a result, the growth of E. siliculosus was temporarily inhibited without persistent genome editing. This study demonstrated the potential for exploring the characteristics of brown algae through a simple yet effective approach and presented a feasible system for delivering siRNA in brown algae.

The Draft Genome of the "Golden Tide" Seaweed, Sargassum horneri: Characterization and Comparative Analysis

Sargassum horneri, a prevalent species of brown algae found along the coast of the northwest Pacific Ocean, holds significant importance as a valuable source of bioactive compounds. However, its rapid growth can lead to the formation of a destructive "golden tide", causing severe damage to the local economy and coastal ecosystems. In this study, we carried out de novo whole-genome sequencing of S. horneri using next-generation sequencing to unravel the genetic information of this alga. By utilizing a reference-guided de novo assembly pipeline with a closely related species, we successfully established a final assembled genome with a total length of 385 Mb. Repetitive sequences made up approximately 30.6% of this genome. Among the identified putative genes, around 87.03% showed homology with entries in the NCBI non-redundant protein database, with Ectocarpus siliculosus being the most closely related species for approximately one-third of these genes. One gene encoding an alkaline phosphatase family protein was found to exhibit positive selection, which could give a clue for the formation of S. horneri golden tides. Additionally, we characterized putative genes involved in fucoidan biosynthesis metabolism, a significant pathway in S. horneri. This study represents the first genome-wide characterization of a S. horneri species, providing crucial insights for future investigations, such as ecological genomic analyses.

Mannuronate C-5 epimerases and their use in alginate modification

Alginate is a polysaccharide consisting of β-D-mannuronate (M) and α-L-guluronate (G) produced by brown algae and some bacterial species. Alginate has a wide range of industrial and pharmaceutical applications, owing mainly to its gelling and viscosifying properties. Alginates with high G content are considered more valuable since the G residues can form hydrogels with divalent cations. Alginates are modified by lyases, acetylases, and epimerases. Alginate lyases are produced by alginate-producing organisms and by organisms that use alginate as a carbon source. Acetylation protects alginate from lyases and epimerases. Following biosynthesis, alginate C-5 epimerases convert M to G residues at the polymer level. Alginate epimerases have been found in brown algae and alginate-producing bacteria, predominantly Azotobacter and Pseudomonas species. The best characterised epimerases are the extracellular family of AlgE1-7 from Azotobacter vinelandii (Av). AlgE1-7 all consist of combinations of one or two catalytic A-modules and one to seven regulatory R-modules, but even though they are sequentially and structurally similar, they create different epimerisation patterns. This makes the AlgE enzymes promising for tailoring of alginates to have the desired properties. The present review describes the current state of knowledge regarding alginate-active enzymes with focus on epimerases, characterisation of the epimerase reaction, and how alginate epimerases can be used in alginate production.

Assembly and synthesis of the extracellular matrix in brown algae

In brown algae, the extracellular matrix (ECM) and its constitutive polymers play crucial roles in specialized functions, including algal growth and development. In this review we offer an integrative view of ECM construction in brown algae. We briefly report the chemical composition of its main constituents, and how these are interlinked in a structural model. We examine the ECM assembly at the tissue and cell level, with consideration on its structure in vivo and on the putative subcellular sites for the synthesis of its main constituents. We further discuss the biosynthetic pathways of two major polysaccharides, alginates and sulfated fucans, and the progress made beyond the candidate genes with the biochemical validation of encoded proteins. Key enzymes involved in the elongation of the glycan chains are still unknown and predictions have been made at the gene level. Here, we offer a re-examination of some glycosyltransferases and sulfotransferases from published genomes. Overall, our analysis suggests novel investigations to be performed at both the cellular and biochemical levels. First, to depict the location of polysaccharide structures in tissues. Secondly, to identify putative actors in the ECM synthesis to be functionally studied in the future.

Brown algal cell walls and development

Brown algae are complex multicellular eukaryotes whose cells possess a cell wall, which is an important structure that regulates cell size and shape. Alginate and fucose-containing sulfated polysaccharides (FCSPs) are two carbohydrate types that have major roles in influencing the mechanical properties of the cell wall (i.e. increasing or decreasing wall stiffness), which in turn regulate cell expansion, division, adhesion, and other processes; however, how brown algal cell wall structure regulates its mechanical properties, and how this relationship influences cellular growth and organismal development, is not well-understood. This chapter is focused on reviewing what we currently know about how the roles of alginates and FCSPs in brown algal developmental processes, as well as how they influence the structural and mechanical properties of cell walls. Additionally, we discuss how brown algal mutants may be leveraged to learn more about the underlying mechanisms that regulate cell wall structure, mechanics, and developmental processes, and finally we propose questions to guide future research with the use of emerging technologies.

Research Progress on the Protective Effect of Brown Algae-Derived Polysaccharides on Metabolic Diseases and Intestinal Barrier Injury

In the human body, the intestine is the largest digestive and immune organ, where nutrients are digested and absorbed, and this organ plays a key role in host immunity. In recent years, intestinal health issues have gained attention and many studies have shown that oxidative stress, inflammation, intestinal barrier damage, and an imbalance of intestinal microbiota may cause a range of intestinal diseases, as well as other problems. Brown algae polysaccharides, mainly including alginate, fucoidan, and laminaran, are food-derived natural products that have received wide attention from scholars owing to their good biological activity and low toxic side effects. It has been found that brown algae polysaccharides can repair intestinal physical, chemical, immune and biological barrier damage. Principally, this review describes the protective effects and mechanisms of brown algae-derived polysaccharides on intestinal health, as indicated by the ability of polysaccharides to maintain intestinal barrier integrity, inhibit lipid peroxidation-associated damage, and suppress inflammatory cytokines. Furthermore, our review aims to provide new ideas on the prevention and treatment of intestinal diseases and act as a reference for the development of fucoidan as a functional product for intestinal protection.

The Cell Wall Polysaccharides Biosynthesis in Seaweeds: A Molecular Perspective

Cell wall polysaccharides (CWPS) of seaweeds play crucial roles in mechanical shear resistance, cell-cell adhesion and the interactions with changeable marine environments. They have diverse applications in food, cosmetics, agriculture, pharmaceuticals and therapeutics. The recent boost of multi-omics sequence analysis has rapidly progressed the mining of presumed genes encoding enzymes involved in CWPS biosynthesis pathways. In this review, we summarize the biosynthetic pathways of alginate, fucoidan, agar, carrageenan and ulvan in seaweeds referred to the literatures on published genomes and biochemical characterization of encoded enzymes. Some transcriptomic data were briefly reported to discuss the correlation between gene expression levels and CWPS contents. Mannuronan C-5 epimerase (MC5E) and carbohydrate sulfotransferase (CST) are crucial enzymes for alginate and sulfated CWPS, respectively. Nonetheless, most CWPS-relevant genes were merely investigated by gene mining and phylogenetic analysis. We offer an integrative view of CWPS biosynthesis from a molecular perspective and discuss about the underlying regulation mechanism. However, a clear understanding of the relationship between chemical structure and bioactivities of CWPS is limited, and reverse genetic manipulation and effective gene editing tools need to be developed in future.

Standard Candles for Dating Microbial Lineages

Molecular clock analyses are challenging for microbial phylogenies, due to a lack of fossil calibrations that can reliably provide absolute time constraints. An alternative source of temporal constraints for microbial groups is provided by the inheritance of proteins that are specific for the utilization of eukaryote-derived substrates, which have often been dispersed across the Tree of Life via horizontal gene transfer. In particular, animal, algal, and plant-derived substrates are often produced by groups with more precisely known divergence times, providing an older-bound on their availability within microbial environments. Therefore, these ages can serve as "standard candles" for dating microbial groups across the Tree of Life, expanding the reach of informative molecular clock investigations. Here, we formally develop the concept of substrate standard candles and describe how they can be propagated and applied using both microbial species trees and individual gene family phylogenies. We also provide detailed evaluations of several candidate standard candles and discuss their suitability in light of their often complex evolutionary and metabolic histories.

Floridean Starch and Floridoside Metabolic Pathways of Neoporphyra haitanensis and Their Regulatory Mechanism under Continuous Darkness

Floridean starch and floridoside are the main storage carbohydrates of red algae. However, their complete metabolic pathways and the origin, function, and regulatory mechanism of their pathway genes have not been fully elucidated. In this study, we identified their metabolic pathway genes and analyzed the changes in related gene expression and metabolite content in Neoporphyra haitanensis under continuous dark conditions. Our results showed that genes from different sources, including eukaryotic hosts, cyanobacteria, and bacteria, were combined to construct floridean starch and floridoside metabolic pathways in N. haitanensis. Moreover, compared with those in the control, under continuous dark conditions, floridean starch biosynthesis genes and some degradation genes were significantly upregulated with no significant change in floridean starch content, whereas floridoside degradation genes were significantly upregulated with a significant decrease in floridoside content. This implies that floridean starch content is maintained but floridoside is consumed in N. haitanensis under dark conditions. This study elucidates the "floridean starch-floridoside" metabolic network and its gene origins in N. haitanensis for the first time.

Bioproduction of biomacromolecules for antiviral applications

The societal damage brought on by viral epidemics indicates that next-generation antiviral treatments must be developed and deployed. Biomacromolecules are a diverse class of compounds that can potentially exhibit potent antiviral activity. Their efficacy and mechanisms of action are dependent upon multiple structural factors, including molecular weight, degree and position of sulfation, and backbone stereochemistry. Extracting biomacromolecules from animals and plants for healthcare applications is undesirable, as these methods are unable to yield products with well-defined chemical structures. Modern advances utilizing recombinant microbes and metabolic pathway engineering can be a key step towards large-scale bioproduction of tailored biomacromolecules for targeted antiviral applications.

Comparative Transcriptome Analysis Reveals Candidate Genes Related to Structural and Storage Carbohydrate Biosynthesis in Kelp Saccharina japonica (Laminariales, Phaeophyceae)

Saccharina japonica is a brown macroalga that has been commercially cultivated in China for almost a century. As a natural raw material, it is widely used in the food and pharmaceutical industries, and it may potentially be useful for biofuel production. However, little is known about the genes involved in carbohydrate biosynthesis, and their regulation is less understood. In this study, the analysis of growth traits and alginate and mannitol contents suggested that sporophyte development could be divided into four stages. Accordingly, we performed transcriptome analysis of the S. japonica sporophyte. In total, 589 million clean reads were generated, and 4,514 novel genes were identified. Gene expression analysis revealed that 2,542 genes were differentially expressed. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that these genes were significantly enriched in "Carbon metabolism," "Photosynthesis," and "Photosynthesis-antenna proteins" pathways, which are important for metabolism of various carbohydrates during sporophyte development. Systematic analysis identified the genes encoding enzymes for the biosynthesis of cell wall carbohydrates (including alginate, fucoidan, and cellulose) and cytoplasm storage carbohydrates (mannitol, laminarin, and trehalose). Among them, some key genes associated with carbohydrate content were further identified based on detailed expression profiling, representing good candidates for further functional studies. This study provides a global view of the carbohydrate metabolism process and an important resource for functional genomics studies in S. japonica. The results obtained lay the basis for elucidating the molecular mechanism of carbohydrate biosynthesis and for genetic breeding of carbohydrates-related traits in kelp.

Bioinformatic Characterization of Sulfotransferase Provides New Insights for the Exploitation of Sulfated Polysaccharides in Caulerpa

Caulerpa is an unusual algal genus from Caulerpaceae (Chlorophyta, Bryopsidales). Species from this family produce a wide range of metabolites suitable for biotechnology applications. Among these, sulfated polysaccharides (SPs) are often highly desirable for pharmaceutical and nutraceutical applications. Here, we provide a classification of sulfotransferases from Caulerpa; these important enzymes catalyze the nodal step for the biosynthesis of SPs. For this, we performed phylogenetic, genomic, expression analyses and prediction of the protein structure on sulfotransferases from Caulerpa. Sequences, domains and structures of sulfotransferases generally shared common characteristics with other plants and algae. However, we found an extensive duplication of sulfotransferase gene family, which is unique among the green algae. Expression analysis revealed specific transcript abundance in the pinnae and rachis of the alga. The unique genomic features could be utilized for the production of complex SPs, which require multiple and specific sulfation reactions. The expansion of this gene family in Caulerpaceae would have resulted in a number of proteins characterizing the unique SPs found in these algae. We provide a putative biosynthetic pathway of SPs, indicating the unique characteristics of this pathway in Caulerpa species. These data may help in the future selection of Caulerpa species for both commercial applications and genetic studies to improve the synthesis of valuable products from Caulerpa.

Transcriptomic and Proteomic Analysis of Mannitol-metabolism-associated Genes in Saccharina japonica

As a carbon-storage compound and osmoprotectant in brown algae, mannitol is synthesized and then accumulated at high levels in Saccharina japonica (Sja); however, the underlying control mechanisms have not been studied. Our analysis of genomic and transcriptomic data from Sja shows that mannitol metabolism is a cyclic pathway composed of four distinct steps. A mannitol-1-phosphate dehydrogenase (M1PDH2) and two mannitol-1-phosphatases (M1Pase1 and MIPase2) work together or in combination to exhibit full enzymatic properties. Based on comprehensive transcriptomic data from different tissues, generations, and sexes as well as under different stress conditions, coupled with droplet digital PCR (ddPCR) and proteomic confirmation, we suggest that SjaM1Pase1 plays a major role in mannitol biosynthesis and that the basic mannitol anabolism and the carbohydrate pool dynamics are responsible for carbon storage and anti-stress mechanism. Our proteomic data indicate that mannitol metabolism remains constant during diurnal cycle in Sja. In addition, we discover that mannitol-metabolism-associated (MMA) genes show differential expression between the multicellular filamentous (gametophyte) and large parenchymal thallus (sporophyte) generations and respond differentially to environmental stresses, such as hyposaline and hyperthermia conditions. Our results indicate that the ecophysiological significance of such differentially expressed genes may be attributable to the evolution of heteromorphic generations (filamentous and thallus) and environmental adaptation of Laminariales.

Genome-wide analysis of the Saccharina japonica sulfotransferase genes and their transcriptional profiles during whole developmental periods and under abiotic stresses

BACKGROUND

As a unique sulfated polysaccharide, fucoidan is an important component of cell wall in brown seaweeds. Its biochemical properties are determined by the positions and quantity of sulfate groups. Sulfotransferases (STs) catalyze the sulfation process, which transfer the sulfuryl groups to carbohydrate backbones and are crucial for fucoidan biosynthesis. Nevertheless, the structures and functions of STs in brown seaweeds are rarely investigated.

RESULTS

There are a total of 44 ST genes identified from our genome and transcriptome analysis of Saccharina japonica, which were located in the 17 scaffolds and 11 contigs. The S. japonica ST genes have abundant introns and alternative splicing sites, and five tandem duplicated gene clusters were identified. Generally, the ST genes could be classified into five groups (Group I ~ V) based on phylogenetic analysis. Accordingly, the ST proteins, which were encoded by genes within the same group, contained similar conserved motifs. Members of the S. japonica ST gene family show various expression patterns in different tissues and developmental stages. Transcriptional profiles indicate that the transcriptional levels of more than half of the ST genes are higher in kelp basal blades than in distal blades. Except for ST5 and ST28, most ST genes are down-regulated with the kelp development stages. The expression levels of nine ST genes were detected by real-time quantitative PCR, which demonstrates that they responded to low salinity and drought stresses.

CONCLUSIONS

Various characteristics of the STs allow the feasibilities of S. japonica to synthesize fucoidans with different sulfate groups. This enables the kelp the potential to adapt to the costal environments and meet the needs of S. japonica growth.

Fucoidans: Downstream Processes and Recent Applications

Fucoidans are multifunctional marine macromolecules that are subjected to numerous and various downstream processes during their production. These processes were considered the most important abiotic factors affecting fucoidan chemical skeletons, quality, physicochemical properties, biological properties and industrial applications. Since a universal protocol for fucoidans production has not been established yet, all the currently used processes were presented and justified. The current article complements our previous articles in the fucoidans field, provides an updated overview regarding the different downstream processes, including pre-treatment, extraction, purification and enzymatic modification processes, and shows the recent non-traditional applications of fucoidans in relation to their characters.

Transcriptome sequencing of Saccharina japonica sporophytes during whole developmental periods reveals regulatory networks underlying alginate and mannitol biosynthesis

BACKGROUND

Alginate is an important cell wall component and mannitol is a soluble storage carbon substance in the brown seaweed Saccharina japonica. Their contents vary with kelp developmental periods and harvesting time. Alginate and mannitol regulatory networks and molecular mechanisms are largely unknown.

RESULTS

With WGCNA and trend analysis of 20,940 known genes and 4264 new genes produced from transcriptome sequencing of 30 kelp samples from different stages and tissues, we deduced that ribosomal proteins, light harvesting complex proteins and "imm upregulated 3" gene family are closely associated with the meristematic growth and kelp maturity. Moreover, 134 and 6 genes directly involved in the alginate and mannitol metabolism were identified, respectively. Mannose-6-phosphate isomerase (MPI2), phosphomannomutase (PMM1), GDP-mannose 6-dehydrogenase (GMD3) and mannuronate C5-epimerase (MC5E70 and MC5E122) are closely related with the high content of alginate in the distal blade. Mannitol accumulation in the basal blade might be ascribed to high expression of mannitol-1-phosphate dehydrogenase (M1PDH1) and mannitol-1-phosphatase (M1Pase) (in biosynthesis direction) and low expression of mannitol-2-dehydrogenase (M2DH) and Fructokinase (FK) (in degradation direction). Oxidative phosphorylation and photosynthesis provide ATP and NADH for mannitol metabolism whereas glycosylated cycle and tricarboxylic acid (TCA) cycle produce GTP for alginate biosynthesis. RNA/protein synthesis and transportation might affect alginate complex polymerization and secretion processes. Cryptochrome (CRY-DASH), xanthophyll cycle, photosynthesis and carbon fixation influence the production of intermediate metabolite of fructose-6-phosphate, contributing to high content of mannitol in the basal blade.

CONCLUSIONS

The network of co-responsive DNA synthesis, repair and proteolysis are presumed to be involved in alginate polymerization and secretion, while upstream light-responsive reactions are important for mannitol accumulation in meristem of kelp. Our transcriptome analysis provides new insights into the transcriptional regulatory networks underlying the biosynthesis of alginate and mannitol during S. japonica developments.

Is geographical variation driving the transcriptomic responses to multiple stressors in the kelp Saccharina latissima?

BACKGROUND

Kelps (Laminariales, Phaeophyceae) are brown macroalgae of utmost ecological, and increasingly economic, importance on temperate to polar rocky shores. Omics approaches in brown algae are still scarce and knowledge of their acclimation mechanisms to the changing conditions experienced in coastal environments can benefit from the application of RNA-sequencing. Despite evidence of ecotypic differentiation, transcriptomic responses from distinct geographical locations have, to our knowledge, never been studied in the sugar kelp Saccharina latissima so far.

RESULTS

In this study we investigated gene expression responses using RNA-sequencing of S. latissima from environments with contrasting temperature and salinity conditions - Roscoff, in temperate eastern Atlantic, and Spitsbergen in the Arctic. Juvenile sporophytes derived from uniparental stock cultures from both locations were pre-cultivated at 8 °C and SA 30. Sporophytes acclimated to 0 °C, 8 °C and 15 °C were exposed to a low salinity treatment (SA 20) for 24 h. Hyposalinity had a greater impact at the transcriptomic level than the temperature alone, and its effects were modulated by temperature. Namely, photosynthesis and pigment synthesis were extensively repressed by low salinity at low temperatures. Although some responses were shared among sporophytes from the different sites, marked differences were revealed by principal component analysis, differential expression and GO enrichment. The interaction between low temperature and low salinity drove the largest changes in gene expression in sporophytes from Roscoff while specimens from Spitsbergen required more metabolic adjustment at higher temperatures. Moreover, genes related to cell wall adjustment were differentially expressed between Spitsbergen and Roscoff control samples.

CONCLUSIONS

Our study reveals interactive effects of temperature and salinity on transcriptomic profiles in S. latissima. Moreover, our data suggest that under identical culture conditions sporophytes from different locations diverge in their transcriptomic responses. This is probably connected to variations in temperature and salinity in their respective environment of origin. The current transcriptomic results support the plastic response pattern in sugar kelp which is a species with several reported ecotypes. Our data provide the baseline for a better understanding of the underlying processes of physiological plasticity and may help in the future to identify strains adapted to specific environments and its genetic control.

Genome-Scale Metabolic Networks Shed Light on the Carotenoid Biosynthesis Pathway in the Brown Algae Saccharina japonica and Cladosiphon okamuranus

Understanding growth mechanisms in brown algae is a current scientific and economic challenge that can benefit from the modeling of their metabolic networks. The sequencing of the genomes of Saccharina japonica and Cladosiphon okamuranus has provided the necessary data for the reconstruction of Genome-Scale Metabolic Networks (GSMNs). The same in silico method deployed for the GSMN reconstruction of Ectocarpus siliculosus to investigate the metabolic capabilities of these two algae, was used. Integrating metabolic profiling data from the literature, we provided functional GSMNs composed of an average of 2230 metabolites and 3370 reactions. Based on these GSMNs and previously published work, we propose a model for the biosynthetic pathways of the main carotenoids in these two algae. We highlight, on the one hand, the reactions and enzymes that have been preserved through evolution and, on the other hand, the specificities related to brown algae. Our data further indicate that, if abscisic acid is produced by Saccharina japonica, its biosynthesis pathway seems to be different in its final steps from that described in land plants. Thus, our work illustrates the potential of GSMNs reconstructions for formalizing hypotheses that can be further tested using targeted biochemical approaches.

Evolution of Complex Thallus Alga: Genome Sequencing of Saccharina japonica

Saccharina, as one of the most important brown algae (Phaeophyceae) with multicellular thallus, has a very remarkable evolutionary history, and globally accounts for most of the economic marine aquaculture production worldwide. Here, we present the 580.5 million base pairs of genome sequence of Saccharina japonica, whose current assembly contains 35,725 protein-coding genes. In a comparative analysis with Ectocarpus siliculosus, the integrated virus sequence suggested the genome evolutionary footprints, which derived from their co-ancestry and experienced genomic arrangements. Furthermore, the gene expansion was found to be an important strategy for functional evolution, especially with regard to extracelluar components, stress-related genes, and vanadium-dependent haloperoxidases, and we proposed a hypothesis that gene duplication events were the main driving force for the evolution history from multicellular filamentous algae to thallus algae. The sequenced Saccharina genome paves the way for further molecular studies and is useful for genome-assisted breeding of S. japonica and other related algae species.

Fucoidan Sulfatases from Marine Bacterium Wenyingzhuangia fucanilytica CZ1127T

Fucoidans belong to a structurally heterogeneous class of sulfated polysaccharides isolated from brown algae. They have a wide spectrum of biological activities. The complex structures of these polysaccharides hinder structure-activity relationships determination. Fucoidan sulfatases can make useful tools for the determination of the fine chemical structure of fucoidans. In this study, identification and preparation of two recombinant sulfatases able to catalyze the cleavage of sulfate groups from fragments of fucoidan molecules is described for the first time. Two genes of sulfatases swf1 and swf4 of the marine bacterium Wenyingzhuangia fucanilytica CZ1127^T were cloned and the proteins were produced in Escherichia coli cells. Sulfatases SWF1 and SWF4 are assigned to S1_17 and S1_25 subfamilies of formylglycine-dependent enzymes of S1 family (SulfAtlas). Some molecular and biochemical characteristics of recombinant fucoidan sulfatases have been studied. Detailed specificity and catalytic features of sulfatases were determined using various sulfated fucooligosaccharides. Structures of products produced by SWF1 and SWF4 were established by nuclear magnetic resonance (NMR) spectroscopy. Based on the obtained data, the enzymes are classified as fucoidan exo-2O-sulfatase (SWF1) and fucoidan exo-3O-sulfatase (SWF4). In addition, we demonstrated the sequential action of sulfatases on 2,3-di-O-sulfated fucooligosacchrides, which indicates an exolitic degradation pathway of fucoidan by a marine bacterium W. fucanilytica CZ1127^T.