Characterisation of a novel laminarinase from Microbulbifer sp. ALW1 and the antioxidant activity of its hydrolysates

Abstract

Laminarin and its derived oligosaccharides have diverse bioactivities. The b-1,3-glucanase in marine bacteria can be employed as a tool to digest laminarin in the cell wall of brown algae. Here, we cloned, expressed and characterised a b-1,3-glucanase (laminarinase), MaLamNA, from the previously characterised marine bacterium Microbulbifer sp. ALW1, phylogenetically distinct from the glycoside hydrolase families of characterised laminarinases. The recombinant laminarinase was heterologously expressed and purified from Pichia pastoris GS115 cells with a molecular mass of 57.3 kDa. MaLamNA exerted its hydrolytic activity specifically against laminarin, with the highest activity at 45°C and pH 4.5-5.5, respectively, and demonstrated high stability against extreme acidic and alkaline pH exposure. The addition of reducing agent dithiothreitol could significantly enhance the activity of MaLamNA. The hydrolytic products of laminarin by MaLamNA exhibited more effective antioxidant activities than the undigested laminarin. These characteristics of MaLamNA provide clues to its industrial application for laminarin bioresource development.

Transcriptome Analysis Reveals the Algicidal Mechanism of Brevibacillus laterosporus against Microcystis aeruginosa through Multiple Metabolic Pathways

“…Hydrolases in algae-lysing bacteria can dissolve the cell wall of cyanobacteria and kill the algal cells. Hu et al [ 21 ] found a β1,3-glucanase in the marine bacteria Microbulbifer sp. ALW1 can digest laminarin in the cell wall of brown algae.…”

Characterisation of marine bacterium Microbulbifer sp. ALW1 with Laminaria japonica degradation capability

“…The reducing sugars produced during incubation with ALW1 cells were probably utilised by the strain to support the cell growth. The ALW1 cells or its related enzymes could be used to produce oligosaccharides or monosaccharides (Hu et al 2021 ; Jiang et al 2019 ; Li et al 2022b ; Zhu et al 2016b ). Algal oligosaccharides have antitumour, antihypertensive, antioxidant and whitening effects, and they also can suppress IgE production, improve the intestinal microflora, and promote cell proliferation and plant growth (Chen et al 2019 ; Jagtap et al 2022 ; Zhu et al 2021 ).…”

“…The polysaccharides tested included alginate, laminarin, fucoidan and cellulose. Enzyme activity was determined following the procedures of the 3,5-dinitrosalicylic acid (DNS) method (Hu et al 2021 ; Jiang et al 2019 ; Li et al 2021a ; Miller 1959 ). The reaction was initiated by adding 2 mL of the crude enzymes to 2 mL of 5 mg/mL individual substrate in 50 mM Na 2 HPO 4 -NaH 2 PO 4 (pH 7.0).…”

“…A collection of enzymes has been isolated from microorganisms and reported to function against the diverse polysaccharide constituents of seaweed cell wall, including alginate (Gao et al 2021 ; Zhu et al 2016b ), agar (Park et al 2020 ; Zhu et al 2016b , c ), carrageenan (Zhu et al 2018 ), laminarin (Hu et al 2021 ), fucoidan (Sichert et al 2020 ) and cellulose (Li et al 2021a ). Complete genomic analysis has also been implemented to understand the genetic elements imparting the polysaccharide degradation ability of seaweed-associated bacteria (Sun et al 2016 ; Zhu et al 2016a ).…”

Potential Prebiotic and Anti-Obesity Effects of Codium fragile Extract

“…These polysaccharides are structurally atypical compared to terrestrial glycans and are resistant to gastric acid, gastrointestinal absorption and host digestive enzymes [7]. In addition, enzymatic hydrolysis of seaweed-derived carbohydrates and proteins promotes changes in physicochemical properties and enhances the efficacy of bioactivities such as antioxidant activity [8,9]. Marine algae polysaccharides can be used as prebiotics for gut microbiota, which partially degrade them into other bioactive compounds, such as oligosaccharides and short chain fatty acids (SCFAs) acting as food sources for these organisms and allowing them to proliferate [10][11][12][13][14].…”