Botany Department, Faculty of Science, Tanta University, 31527 Tanta, Egypt.
Botany Department, Faculty of Science, Tanta University, 31527 Tanta, Egypt; Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China.
Int J Biol Macromol. 2022 Jan 31;196:35-45. doi: 10.1016/j.ijbiomac.2021.12.033. Epub 2021 Dec 15.
The exploitation of chitinous materials seems to be an infinite treasure. To this end, using shellfish waste as the sole carbon/nitrogen source solves environmental challenges while lowering microbial chitinase production costs. Bioconversion of shellfish chitin wastes such as shrimp shells has recently been investigated for the production of enzymes and bioactive materials in order to maximize the utilization of chitin-containing seafood processing wastes. In this study, the bioconversion of chitin to chitosan by Alcaligenes faecalis Alca F2018 revealed the highest chitin deacetylase (CDA) activity of 40.6 U/μg. The resulted low K and high V values explain the high affinity of the purified CDA to the p-nitroacetanilide substrate. CDA with a molecular weight of 66 KDa was purified from F2018 strain, with a 14.5% yield. FT-IR revealed distinct chitosan peaks and XRD revealed that chitosan samples had lower crystallinity than chitin. TGA analysis revealed that the recovered chitosan samples were more thermally stable. The deacetylation degree percentages of the produced chitosan are in the same range as that of the commercial chitosan, suggesting the promising potential of A. faecalis Alca F2018 to utilize shrimp shells in their raw form in the fermentation media based on its CDA enzyme activity.
甲壳素材料的开发似乎是一座无穷无尽的宝藏。为此，利用贝类废物作为唯一的碳/氮源，既解决了环境挑战，又降低了微生物甲壳素酶的生产成本。最近，人们研究了利用贝类废弃物（如虾壳）进行生物转化，以生产酶和生物活性物质，从而最大限度地利用含甲壳素的海鲜加工废弃物。在本研究中，通过 Alcaligenes faecalis Alca F2018 将甲壳素生物转化为壳聚糖，发现其甲壳素脱乙酰酶（CDA）活性最高，达到 40.6 U/μg。低 K 和高 V 值表明纯化的 CDA 对 p-硝基乙酰苯胺底物具有高亲和力。分子量为 66 kDa 的 CDA 从 F2018 菌株中纯化得到，产率为 14.5%。FT-IR 显示出明显的壳聚糖峰，XRD 显示壳聚糖样品的结晶度低于甲壳素。TGA 分析表明，回收的壳聚糖样品具有更高的热稳定性。所生产壳聚糖的脱乙酰度百分比与商业壳聚糖相当，这表明 A. faecalis Alca F2018 具有利用虾壳作为发酵培养基中原始原料的巨大潜力，这与其 CDA 酶活性有关。
