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Green algae, particularly Ulva species, are rich in complex polysaccharides, such as ulvan, which have significant potential for biotechnological applications. However, the biochemical properties of ulvan depolymerised products remain underexplored. The enzymatic depolymerisation of ulvan has garnered attention owing to its cost advantages over alternative methods. Nevertheless, the biochemical characterisation of ulvan lyases, specifically those belonging to the polysaccharide lyase family 25 (PL25), is limited. In this study, we identified and biochemically characterised a novel PL25 ulvan lyase, PaUL25, which functions optimally at pH 10. Additionally, we explored the alpha (α)-glucosidase inhibitory properties of ulvan depolymerised products. PaUL25 exhibited optimum activity at 35 °C in Tris-HCl buffer (pH 10). Moreover, enzyme activity was enhanced by more than 150% in the presence of Mn2+ metal ions at and below concentrations of 10 mM. The endolytic action of PaUL25 produced ulvan oligosaccharides with degrees of polymerisation of 2 and 4 as its end products. Partially and completely hydrolysed ulvan oligosaccharides exhibited α-glucosidase inhibitory activity, with half inhibitory concentration IC50 values of 3.21 ± 0.13 and 2.51 ± 0.19 mg/mL, respectively. These findings expand our understanding of PL25 and highlight the pharmaceutical potential of ulvan oligosaccharides, particularly as antidiabetic agents. [ABSTRACT FROM AUTHOR]

In this study, we report the molecular and enzymatic characterisation of Spg103, a novel bifunctional β-glucanase from the marine bacterium Streptomyces sp. J103. Recombinant Spg103 (rSpg103) functioned optimally at 60 °C and pH 6. Notably, Spg103 exhibited distinct stability properties, with increased activity in the presence of Na+ and EDTA. Spg103 displays both lichenase and cellobiohydrolase activity. Despite possessing a GH5 cellulase domain, FN3 and CBM3 domains characteristic of cellulases and CBHs, biochemical assays showed that rSpg103 exhibited higher activity towards mixed β-1,3-1,4-glucan such as barley β-glucan and lichenan than towards beta-1,4-linkages. The endolytic activity of the enzyme was confirmed by TLC and UPLC-MS analyses, which identified cellotriose as the main hydrolysis product. In addition, Spg103 exhibited an exo-type activity, selectively releasing cellobiose units from cellooligosaccharides, which is characteristic of cellobiohydrolases. These results demonstrate the potential of Spg103 for a variety of biotechnological applications, particularly those requiring tailor-made enzymatic degradation of mixed-linked β-glucans. This study provides a basis for further structural and functional investigations of the bifunctional enzyme and highlights Spg103 as a promising candidate for industrial applications. [ABSTRACT FROM AUTHOR]

Agarases produce agar oligosaccharides with various structures exhibiting diverse physiological activities. α-Neoagaro-oligosaccharide hydrolase (α-NAOSH) specifically cleaves even-numbered neoagaro-oligosaccharides, producing 3,6-anhydro-l-galactose (l-AHG) and odd-numbered agaro-oligosaccharides (OAOSs). In this study, α-NAOSH from the agar-degrading marine bacterium Gilvimarinus agarilyticus JEA5 (Gaa117) was purified and characterized using an E. coli expression system to produce OAOSs and determine their bioactivity. Recombinant Gaa117 (rGaa117) showed maximum activity at pH 6.0 and 35 °C. rGaa117 retained >80% of its initial activity after 120 min at 30 °C. The activity was enhanced in the presence of Mn2+. Km, Vmax, and Kcat/Km values of the enzyme were 22.64 mM, 246.3 U/mg, and 15 s−1/mM, respectively. rGaa117 hydrolyzed neoagarobiose, neoagarotetraose, and neoagarohexaose, producing OAOSs that commonly contained l-AHG. Neoagarobiose and neoagarotetraose mixtures, designated NAO24, and mixtures of l-AHG and agarotriose, designated AO13, were obtained using recombinant rGaa16B (β-agarase) and rGaa117, respectively, and their antioxidant activities were compared. AO13 showed higher hydrogen peroxide-scavenging activity than NAO24 in human dermal fibroblasts in vitro because of structural differences: AOSs have d-galactose at the non-reducing end, whereas NAOSs have l-AHG. In conclusion, OAOSs exhibited high ROS-scavenging activity in H2O2-induced human dermal fibroblasts. They may be applicable in cosmetics and pharmaceuticals for prevention of skin aging. [ABSTRACT FROM AUTHOR]

The development of serum-free media (SFM) is critical to advance cell culture techniques used in viral vaccine production and address the ethical concerns and contamination risks associated with fetal bovine serum (FBS). This study evaluated the effects of marine microalgal extracts and growth factor cocktails on the activity of Madin-Darby canine kidney (MDCK) and Vero cells. Five marine microalgal species were used: Spirulina platensis (SP), Dunaliella salina (DS), Haematococcus pluvialis (HP), Nannochloropsis salina (NS), and Tetraselmis sp. (TS). DS and SP extracts significantly increased the proliferation rate of both MDCK and Vero cells. DS had a proliferation rate of 149.56% and 195.50% in MDCK and Vero cells, respectively, compared with that in serum-free medium (SFM). Notably, DS and SP extracts significantly increased superoxide dismutase (SOD) activity, which was 118.61% in MDCK cells and 130.08% in Vero cells for DS, and 108.72% in MDCK cells and 125.63% in Vero cells for SP, indicating a reduction in intracellular oxidative stress. Marine microalgal extracts, especially DS and SP, are feasible alternatives to FBS in cell culture as they promote cell proliferation, ensure safety, and supply essential nutrients while reducing oxidative stress. [ABSTRACT FROM AUTHOR]

Abstract: The P and S velocity ratio, V P /V S , is a seismic property that is convertible to Poisson’s ratio, a widely-analyzed physical property of elastic materials. The lateral variation in the V P /V S ratios of the upper crust of the southern Korean Peninsula is investigated based on the travel times of P and S waves of local events with epicentral distances of 50km or less and focal depths of 25km or less. The dense seismic networks in the Korean Peninsula allow us to investigate the regional variation of V P /V S ratios. These V P /V S ratios are estimated to be 1.60–1.91 with an average of 1.69. The V P /V S ratios are as high as 1.73–1.91 in the Gyeongsang basin, Jeju island and offshore region of the eastern Okcheon belt, but have relatively low values of 1.64–1.72 in Precambrian massif regions. The stability of the V P /V S ratios is tested with randomly-resampled travel-time data, the results of which suggest nearly constant V P /V S ratios with increasing depth in the upper crust. The influences of plausible errors on origin times and arrival times are quantified to verify the V P /V S estimates. The V P /V S ratios are correlated with geological and tectonic structures. Comparisons with known seismic and geophysical properties suggest that structural features observed on the surface may extend at least to the mantle lid. [Copyright &y& Elsevier]

We recently identified a β-agarase, Gaa16B, in the marine bacterium Gilvimarinus agarilyticus JEA5. Gaa16B, belonging to the glycoside hydrolase 16 family of β-agarases, shows less than 70.9% amino acid similarity with previously characterized agarases. Recombinant Gaa16B lacking the carbohydrate-binding region (rGaa16Bc) was overexpressed in Escherichia coli and purified. Activity assays revealed the optimal temperature and pH of rGaa16Bc to be 55 °C and pH 6–7, respectively, and the protein was highly stable at 55 °C for 90 min. Additionally, rGaa16Bc activity was strongly enhanced (2.3-fold) in the presence of 2.5 mM MnCl2. The Km and Vmax of rGaa16Bc for agarose were 6.4 mg/mL and 953 U/mg, respectively. Thin-layer chromatography analysis revealed that rGaa16Bc can hydrolyze agarose into neoagarotetraose and neoagarobiose. Partial hydrolysis products (PHPs) of rGaa16Bc had an average molecular weight of 88–102 kDa and exhibited > 60% hyaluronidase inhibition activity at a concentration of 1 mg/mL, whereas the completely hydrolyzed product (CHP) showed no hyaluronidase at the same concentration. The biochemical properties of Gaa16B suggest that it could be useful for producing functional neoagaro-oligosaccharides. Additionally, the PHP of rGaa16Bc may be useful in promoting its utilization, which is limited due to the gel strength of agar. [ABSTRACT FROM AUTHOR]

Ulvan is a complex sulfated polysaccharide in the cell walls of green algae with extensive applications in food, pharmaceutical, and agricultural industries, prompting extensive studies on ulvan, its oligosaccharides, monosaccharides, and cost-effective depolymerization methods. Our primary objectives were to investigate novel ulvan-utilizing marine bacteria, perform recombinant engineering of genes responsible for ulvan depolymerization, and determine their potential industrial applications. Samples were collected from Jeju Island, which is a South Korean region with significant excessive green algal growth, especially that of Ulva species. The marine bacterium Pseudoalteromonas agarivorans efficiently uses ulvan as its primary carbon source, indicating its potential for ulvan degradation. Through whole-genome sequencing the paul40 gene, which is a polysaccharide lyase family 40 (PL40) member, was identified and subsequently engineered into the pET-16b vector for expression as a His-tagged 95 kDa fusion protein. The ulvan depolymerization process was evaluated and confirmed using various analytical techniques including dinitrosalicylic acid assay, thin-layer chromatography, and gel permeation chromatography. Optimal enzyme activity occurred at 35°C, pH 8.0 in phosphate buffer, and 2.5 mM of NaCl. Furthermore, enzyme characterization and specific activity measurements were performed. This study is the first to report hyaluronidase and elastase inhibition by ulvan and its derivatives along with the characterization of an ulvan lyase enzyme from the PL40 family., One-Sentence Summary: This study reports the identification and recombinant expression of a novel ulvan-degrading enzyme from Pseudoalteromonas agarivorans, demonstrating its potential for cosmetic industrial applications by revealing ulvan's and partially hydrolyzed ulvan's hyaluronidase and elastase inhibition properties., (© The Author(s) 2025. Published by Oxford University Press on behalf of Society of Industrial Microbiology and Biotechnology.)

The agarase gene gaa16a was identified from a draft genome sequence of Gilvimarinus agarilyticus JEA5, an agar-utilizing marine bacterium. Recently, three agarase-producing bacteria, G. chinensis , G. polysaccharolyticus , and G. agarilyticus , in the genus Gilvimarinus were reported. However, there have been no reports of the molecular characteristics and biochemical properties of these agarases. In this study, we analyzed the molecular characteristics and biochemical properties of agarases in Gilvimarinus . Gaa16A comprised a 1,323-bp open reading frame encoding 441 amino acids. The predicted molecular mass and isoelectric point were 49 kDa and 4.9, respectively. The amino acid sequence of Gaa16A showed features typical of glycosyl hydrolase family 16 (GH16) β-agarases, including a GH16 domain, carbohydrate-binding region (RICIN domain), and signal peptide. Recombinant Gaa16A (excluding the signal peptide and carbohydrate-binding region, rGaa16A) was expressed as a fused protein with maltose-binding protein at its N-terminus in Escherichia coli . rGaa16A had maximum activity at 55°C and pH 7.0 and 103 U/mg of specific activity in the presence of 2.5 mM CaCl₂. The enzyme hydrolyzed agarose to yield neoagarotetraose as the main product. This enzyme may be useful for industrial production of functional neoagaro-oligosaccharides.