Institute of Biochemistry, Department of Biotechnology and Enzyme Catalysis, Greifswald University, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany.
Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria.
Appl Microbiol Biotechnol. 2018 Aug;102(16):6987-6996. doi: 10.1007/s00253-018-9142-y. Epub 2018 Jun 12.
Carbohydrates are the product of carbon dioxide fixation by algae in the ocean. Their polysaccharides are depolymerized by marine bacteria, with a vast array of carbohydrate-active enzymes. These enzymes are important tools to establish biotechnological processes based on algal biomass. Green tides, which cover coastal areas with huge amounts of algae from the genus Ulva, represent a globally rising problem, but also an opportunity because their biomass could be used in biorefinery processes. One major component of their cell walls is the anionic polysaccharide ulvan for which the enzymatic depolymerization remains largely unknown. Ulvan lyases catalyze the initial depolymerization step of this polysaccharide, but only a few of these enzymes have been described. Here, we report the cloning, overexpression, purification, and detailed biochemical characterization of the endolytic ulvan lyase from Formosa agariphila KMM 3901 which is a member of the polysaccharide lyase family PL28. The identified biochemical parameters of the ulvan lyase reflect adaptation to the temperate ocean where the bacterium was isolated from a macroalgal surface. The NaCl concentration has a high influence on the turnover number of the enzyme and the affinity to ulvan. Divalent cations were shown to be essential for enzyme activity with Ca likely being the native cofactor of the ulvan lyase. This study contributes to the understanding of ulvan lyases, which will be useful for future biorefinery applications of the abundant marine polysaccharide ulvan.
碳水化合物是海洋中藻类固定二氧化碳的产物。它们的多糖被海洋细菌解聚，这些细菌拥有大量的碳水化合物活性酶。这些酶是建立基于藻类生物质的生物技术过程的重要工具。绿潮是一个全球性的问题，因为它们会在沿海地区覆盖大量的浒苔属藻类，但这也是一个机会，因为它们的生物质可以用于生物炼制过程。其细胞壁的一个主要成分是阴离子多糖岩藻聚糖，其酶解聚在很大程度上尚不清楚。岩藻聚糖裂解酶催化这种多糖的初始解聚步骤，但只有少数几种酶被描述过。在这里，我们报告了 Formosa agariphila KMM 3901 内切岩藻聚糖酶的克隆、过表达、纯化和详细的生化特性，该酶属于多糖裂解酶家族 PL28。鉴定出的岩藻聚糖酶的生化参数反映了其对温带海洋的适应，该细菌是从大型海藻表面分离出来的。NaCl 浓度对酶的周转率和对岩藻聚糖的亲和力有很大影响。二价阳离子对酶活性是必需的，Ca 可能是岩藻聚糖裂解酶的天然辅因子。这项研究有助于理解岩藻聚糖酶，这对于未来丰富的海洋多糖岩藻聚糖的生物炼制应用将是有用的。
