A prerequisite for the transition toward a biobased economy is the identification and development of efficient enzymes for the usage of renewable resources as raw material. Therefore, different xylanolytic enzymes are important for efficient enzymatic hydrolysis of xylan-heteropolymers. A powerful tool to overcome the limited enzymatic toolbox lies in exhausting the potential of unexplored habitats. By screening a Vietnamese fungal culture collection of 295 undiscovered fungal isolates, 12 highly active xylan degraders were identified. One of the best xylanase producing strains proved to be an Aspergillus sydowii strain from shrimp shell (Fsh102), showing a specific activity of 0.6 U/mg. Illumina dye sequencing was used to identify our Fsh102 strain and determine differences to the A. sydowii CBS 593.65 reference strain. With activity based in-gel zymography and subsequent mass spectrometric identification, three potential proteins responsible for xylan degradation were identified. Two of these proteins were cloned from the cDNA and, furthermore, expressed heterologously in Escherichia coli and characterized. Both xylanases, were entirely different from each other, including glycoside hydrolases (GH) families, folds, substrate specificity, and inhibition patterns. The specific enzyme activity applying 0.1% birch xylan of both purified enzymes were determined with 181.1 ± 37.8 or 121.5 ± 10.9 U/mg for xylanase I and xylanase II, respectively. Xylanase I belongs to the GH11 family, while xylanase II is member of the GH10 family. Both enzymes showed typical endo-xylanase activity, the main products of xylanase I are xylobiose, xylotriose, and xylohexose, while xylobiose, xylotriose, and xylopentose are formed by xylanase II. Additionally, xylanase II showed remarkable activity toward xylotriose. Xylanase I is stable when stored up to 30°C and pH value of 9, while xylanase II started to lose significant activity stored at pH 9 after exceeding 3 days of storage. Xylanase II displayed about 40% activity when stored at 50°C for 24 h. The enzymes are tolerant toward mesophilic temperatures, while acting in a broad pH range. With site directed mutagenesis, the active site residues in both enzymes were confirmed. The presented activity and stability justify the classification of both xylanases as highly interesting for further development.

向生物经济转型的先决条件是识别和开发高效酶，以可再生资源为原材料。因此，不同的木聚糖分解酶对于木聚糖杂聚物的有效酶水解非常重要。克服有限的酶工具箱的一个强大工具在于耗尽未开发栖息地的潜力。通过筛选越南真菌培养物，其中包含 295 种未发现的真菌分离株，鉴定出 12 种高活性木聚糖降解剂。事实证明，最好的木聚糖酶生产菌株之一是休氏曲霉来自虾壳的菌株 (Fsh102)，显示出 0.6 U/mg 的比活性。Illumina 染料测序用于鉴定我们的 Fsh102 菌株并确定与西多维阿.CBS 593.65 参考菌株。通过基于活性的凝胶内酶谱分析和随后的质谱鉴定，鉴定出负责木聚糖降解的三种潜在蛋白质。其中两个蛋白质是从 cDNA 中克隆出来的，并且在大肠杆菌并进行了表征。两种木聚糖酶彼此完全不同，包括糖苷水解酶 (GH) 家族、折叠、底物特异性和抑制模式。使用 0.1% 桦木木聚糖测定两种纯化酶的比酶活性，木聚糖酶 I 和木聚糖酶 II 分别为 181.1 ± 37.8 或 121.5 ± 10.9 U/mg。木聚糖酶 I 属于 GH11 家族，而木聚糖酶 II 属于 GH10 家族。两种酶都表现出典型的内切木聚糖酶活性，木聚糖酶I的主要产物是木二糖、木三糖和木己糖，而木聚糖酶II形成木二糖、木三糖和木五糖。此外，木聚糖酶 II 对木三糖表现出显着的活性。木聚糖酶 I 在 30°C、pH 值 9 的储存条件下保持稳定，而木聚糖酶 II 在 pH 9 的条件下储存超过 3 天后开始失去显着活性。木聚糖酶 II 在 50°C 保存 24 小时时显示出约 40% 的活性。这些酶能够耐受中温温度，同时在较宽的 pH 范围内发挥作用。通过定点诱变，确认了两种酶的活性位点残基。所呈现的活性和稳定性证明这两种木聚糖酶的分类是非常值得进一步开发的。