Viewing the considerable potential of marine agar as a source for the sustainable production of energy as well as nature-derived pharmaceutics, this work investigated the catalytic activity of three novel GH50 agarases from the mesophilic marine bacterium Microbulbifer elongatus PORT2 isolated from Indonesian coastal seawaters. The GH50 agarases AgaA50, AgaB50, and AgaC50 were identified through genome analysis; the corresponding genes were cloned and expressed in Escherichia coli BL21 (DE3). All recombinant agarases hydrolyzed β-p-nitrophenyl galactopyranoside, indicating β-glycosidase characteristics. AgaA50 and AgaB50 were able to cleave diverse natural agar species derived from Indonesian agarophytes, indicating a promising tolerance of these enzymes for substrate modifications. All three GH50 agarases degraded agarose, albeit with remarkable diversity in their catalytic activity and mode of action. AgaA50 and AgaC50 exerted exolytic activity releasing differently sized neoagarobioses, while AgaB50 showed additional endolytic activity in dependence on the substrate size. Surprisingly, AgaA50 and AgaB50 revealed considerable thermostability, retaining over 75% activity after 1-h incubation at 50 °C. Considering the thermal properties of agar, this makes these enzymes promising candidates for industrial processing.

鉴于海洋琼脂作为可持续生产能源和天然药物来源的巨大潜力，这项工作研究了从印度尼西亚沿海海水中分离出的中温海洋细菌Microbulbifer elongatus PORT2 中的三种新型 GH50 琼脂酶的催化活性。通过基因组分析鉴定出GH50琼脂酶AgaA50、AgaB50和AgaC50；相应的基因被克隆并在大肠杆菌BL21（DE3）中表达。所有重组琼脂酶都水解 β- p-硝基苯基吡喃半乳糖苷，表明β-糖苷酶特性。AgaA50 和 AgaB50 能够切割来自印度尼西亚琼脂植物的多种天然琼脂物种，这表明这些酶对底物修饰具有良好的耐受性。所有三种 GH50 琼脂酶均可降解琼脂糖，尽管它们的催化活性和作用方式具有显着的多样性。AgaA50 和 AgaC50 发挥外切活性，释放不同大小的新琼脂糖，而 AgaB50 根据底物大小表现出额外的内切活性。令人惊讶的是，AgaA50 和 AgaB50 显示出相当大的热稳定性，在 50 °C 孵育 1 小时后仍保持超过 75% 的活性。考虑到琼脂的热特性，这使得这些酶有望成为工业加工的候选者。