Liaqat Fakhra, Akgün İsmail Hakki, Khazi Mahammed Ilyas, Eltem Rengin
Department of Biotechnology, Graduate School of Natural and Applied Sciences, Ege University, Izmir, Turkiye.
Department of Bioengineering, Faculty of Engineering, Ege University, Izmir, Turkiye.
J Basic Microbiol. 2023 Mar;63(3-4):404-416. doi: 10.1002/jobm.202200123. Epub 2022 Jul 18.
Chitosanases are potential candidates for chitooligosaccharides (COS) production-based industries, therefore, the discovery of chitosanases having commercial potential will remain a priority worldwide. This study aims to characterize different chitosanases of Bacillus strains for COS production. Six different indigenous Bacillus strains (B. cereus EGE-B-6.1m, B. cereus EGE-B-2.5m, B. cereus EGE-B-5.5m, B. cereus EGE-B-10.4i, B. thuringiensis EGE-B-3.5m, and B. mojavensis EGE-B-5.2i) were used to purify and characterize chitosanases. All purified chitosanases have a similar molecular weight (37 kDa) as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, other characteristics such as optimum temperature and pH, kinetic parameters (K and V ), temperature, and pH stabilities were dissimilar among the strains of different Bacillus species and within the same species. Furthermore, chitosanases of all strains were able to successfully hydrolyze chitosan to COS and oligomers of the degree of polymerization 2-6 were detected with chitobiose and chitotriose as major hydrolysis products. The relative yields of COS were in a range of 19%-31% and chitosanase of B. thuringiensis EGE-B-3.5m turned out to be the best enzyme in terms of its characteristics and COS production potential with maximum relative yield (31%). Results revealed that Bacillus chitosanases could be used directly for efficient bioconversion of chitosan into COS and will be valuable for large-scale production of biologically active COS.
壳聚糖酶是基于壳寡糖（COS）生产行业的潜在候选酶，因此，发现具有商业潜力的壳聚糖酶仍将是全球的首要任务。本研究旨在对芽孢杆菌菌株的不同壳聚糖酶进行表征以用于COS生产。使用六种不同的本地芽孢杆菌菌株（蜡样芽孢杆菌EGE - B - 6.1m、蜡样芽孢杆菌EGE - B - 2.5m、蜡样芽孢杆菌EGE - B - 5.5m、蜡样芽孢杆菌EGE - B - 10.4i、苏云金芽孢杆菌EGE - B - 3.5m和莫哈韦芽孢杆菌EGE - B - 5.2i）来纯化和表征壳聚糖酶。通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳测定，所有纯化的壳聚糖酶具有相似的分子量（37 kDa）。然而，不同芽孢杆菌属菌株之间以及同一菌株内的其他特性，如最适温度和pH、动力学参数（K和V）、温度和pH稳定性是不同的。此外，所有菌株的壳聚糖酶都能够成功地将壳聚糖水解为COS，并且检测到聚合度为2 - 6的低聚物，其中壳二糖和壳三糖是主要水解产物。COS的相对产量在19% - 31%范围内，苏云金芽孢杆菌EGE - B - 3.5m的壳聚糖酶在特性和COS生产潜力方面表现最佳，相对产量最高（31%）。结果表明，芽孢杆菌壳聚糖酶可直接用于壳聚糖向COS的高效生物转化，对于生物活性COS的大规模生产具有重要价值。
