Tran Thi Ngoc, Doan Chien Thang, Nguyen Minh Trung, Nguyen Van Bon, Vo Thi Phuong Khanh, Nguyen Anh Dzung, Wang San-Lang
Department of Chemical and Materials Engineering, Tamkang University, New Taipei City 25137, Taiwan.
Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan.
Polymers (Basel). 2019 Sep 30;11(10):1600. doi: 10.3390/polym11101600.
Marine chitinous byproducts possess significant applications in many fields. In this research, different kinds of fishery chitin-containing byproducts from shrimp (shrimp head powder (SHP) and demineralized shrimp shell powder), crab (demineralized crab shell powder), as well as squid (squid pen powder) were used to provide both carbon and nitrogen (C/N) nutrients for the production of an exochitinase via TKU048, a chitinolytic bacterium isolated from Taiwanese soils. TKU048 expressed the highest exochitinase productivity (45.668 U/mL) on 1.5% SHP-containing medium at 37 °C for 2 days. Molecular weight determination analysis basing on polyacrylamide gel electrophoresis revealed the mass of TKU048 exochitinase was approximately 21 kDa. The characterized exochitinase expressed some interesting properties, for example acidic pH optima (pH 3 and pH 5-7) and a higher temperature optimum (60 °C). Furthermore, the main hydrolysis mechanism of TKU048 exochitinase was -acetyl-β-glucosaminidase-like activity; its most suitable substrate was β-chitin powder. The hydrolysis experiment revealed that TKU048 exochitinase was efficient in the cleavage of β-chitin powder, thereby releasing -acetyl-d-glucosamine (GlcNAc, monomer unit of chitin structure) as the major product with 0.335 mg/mL of GlcNAc concentration and a yield of 73.64% after 96 h of incubation time. Thus, TKU048 exochitinase may have potential in GlcNAc production due to its -acetyl-β-glucosaminidase-like activity.
海洋甲壳素副产品在许多领域都有重要应用。在本研究中，来自虾（虾头粉（SHP）和脱矿虾壳粉）、蟹（脱矿蟹壳粉）以及鱿鱼（鱿鱼笔粉）的不同种类含甲壳素渔业副产品被用于为通过从台湾土壤中分离出的几丁质分解细菌TKU048生产外切几丁质酶提供碳和氮（C/N）养分。TKU048在含1.5% SHP的培养基上于37°C培养2天时表现出最高的外切几丁质酶生产力（45.668 U/mL）。基于聚丙烯酰胺凝胶电泳的分子量测定分析表明，TKU048外切几丁质酶的质量约为21 kDa。所表征的外切几丁质酶表现出一些有趣的特性，例如最适酸性pH值（pH 3和pH 5 - 7）以及较高的最适温度（60°C）。此外，TKU048外切几丁质酶的主要水解机制是类似N - 乙酰 - β - 葡萄糖苷酶的活性；其最合适的底物是β - 甲壳素粉。水解实验表明，TKU048外切几丁质酶在β - 甲壳素粉的裂解方面效率很高，从而释放出N - 乙酰 - D - 葡萄糖胺（GlcNAc，甲壳素结构的单体单元）作为主要产物，在孵育96小时后GlcNAc浓度为0.335 mg/mL，产率为73.64%。因此，由于其类似N - 乙酰 - β - 葡萄糖苷酶的活性，TKU048外切几丁质酶在GlcNAc生产中可能具有潜力。
