Rani T Swaroopa, Takahashi Daisuke, Mukherjee Saumashish, Uemura Matsuo, Madhuprakash Jogi, Podile Appa Rao
Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500046, Telangana, India; GITAM School of Science, GITAM deemed (to be) University, Rudrarum, Sangareddy District, 502329, Telangana, India.
Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakuraku, Saitama 338-8570, Japan.
Carbohydr Polym. 2025 Apr 1;353:123272. doi: 10.1016/j.carbpol.2025.123272. Epub 2025 Jan 14.
Chitin's robust structure poses significant challenges for degradation, necessitating the study of microbial processes in chitin-rich environments. We assessed the chitinolytic bacterium Chitiniphilus shinanonensis DSM 23277 (SAY3) for converting chitin biomass into valuable saccharides using various substrates (chitin flakes, α-chitin, and β-chitin) in shake flask cultures. The bacterium successfully grew on all substrates, achieving complete degradation, although chitin flakes required more time. Maximum growth was observed on β-chitin, followed by α-chitin and chitin flakes. Scanning electron microscopy confirmed bacterial colonization and potential hydrolytic activity on chitin flakes. Proteomic analysis via nanoLC-MS/MS identified 32 chitin-degrading enzymes distributed across secretome, periplasmic, and intracellular fractions, with a notable expression of glycoside hydrolases (families 18, 19, and 20), carbohydrate esterases (family 4), and auxiliary activity proteins (family 10). Among the family 18 chitinases, ChiM, ChiI, and ChiL were significantly upregulated on all chitinous substrates compared to glucose. The chitin-active-secretome exhibited optimal activity at pH 8.0 and 45 °C in 50 mM Tris-HCl. Moreover, the chitin-active-secretome effectively degraded chitin flakes, α-chitin, and β-chitin into chitobiose and GlcNAc, with β-chitin yielding the highest chitobiose levels. The diverse chitin-degrading enzymes of C. shinanonensis efficiently utilize recalcitrant chitin as a carbon and energy source, underscoring its industrial potential for chitin degradation.
几丁质坚固的结构给其降解带来了重大挑战，因此有必要研究富含几丁质环境中的微生物过程。我们评估了几丁质分解菌信州几丁质杆菌DSM 23277（SAY3）在摇瓶培养中利用各种底物（几丁质薄片、α-几丁质和β-几丁质）将几丁质生物质转化为有价值糖类的能力。该细菌在所有底物上均能成功生长并实现完全降解，不过几丁质薄片所需时间更长。在β-几丁质上观察到最大生长量，其次是α-几丁质和几丁质薄片。扫描电子显微镜证实了细菌在几丁质薄片上的定殖和潜在水解活性。通过nanoLC-MS/MS进行的蛋白质组分析鉴定出32种几丁质降解酶，分布在分泌组、周质和细胞内部分，糖苷水解酶（第18、19和20家族）、碳水化合物酯酶（第4家族）和辅助活性蛋白（第10家族）有显著表达。在第18家族的几丁质酶中，与葡萄糖相比，ChiM、ChiI和ChiL在所有含几丁质的底物上均显著上调。几丁质活性分泌组在50 mM Tris-HCl中于pH 8.0和45°C时表现出最佳活性。此外，几丁质活性分泌组能有效地将几丁质薄片、α-几丁质和β-几丁质降解为壳二糖和N-乙酰葡糖胺，β-几丁质产生的壳二糖水平最高。信州几丁质杆菌多样的几丁质降解酶能有效利用顽固的几丁质作为碳源和能源，突出了其在几丁质降解方面的工业潜力。
