Xie Junjie, Yin Doudou, Ou Junchao, Lu Bo, Liao Siming, Yang Dengfeng, Zhang Hongyan, Shen Naikun
Guangxi Key Laboratory for Polysaccharide Materials and Modifications, School of Marine Sciences and Biotechnology, Guangxi Minzu University, Nanning, China.
Guangxi Key Laboratory of Marine Natural Products and Combinatorial Biosynthesis Chemistry, Guangxi Beibu Gulf Marine Research Center, Guangxi Academy of Sciences, Nanning, China.
Front Microbiol. 2024 Jul 24;15:1427143. doi: 10.3389/fmicb.2024.1427143. eCollection 2024.
Chitin, abundant in marine environments, presents significant challenges in terms of transformation and utilization. A strain, T22.7.1, with notable chitin deacetylation capabilities, was isolated from the rhizosphere of in the North Sea of China. Comparative 16S rDNA sequence analysis showed that the new isolate had the highest sequence similarity (99.79%) with CSLK01-03, followed by DSM 43338, JC435, and 10bc312 (98.97%, 98.81%, and 98.83%, respectively). Subsequent genome sequencing and phylogenetic analysis confirmed that strain T22.7.1 belongs to the species. However, additional taxonomic characterization identified strain T22.7.1 as a novel type strain of distinct from CSLK01-03.
This study refines the taxonomic description of and investigates its application in converting chitin into chitosan. The chitin deacetylase (CDA) activity of strain T22.7.1 was optimized, and the enzyme was isolated and purified from the fermentation products.
Through optimization, the CDA activity of strain T22.7.1 reached 287.02 U/mL, which is 34.88 times greater than the original enzyme's activity (8.0 U/mL). The natural CDA enzyme was purified with a purification factor of 31.83, and the specific activity of the enzyme solution reached 1200.33 U/mg. CDA exhibited good pH and temperature adaptability and stability, along with a wide range of substrate adaptabilities, effectively deacetylating chitin, chitooligosaccharides, N-acetylglucosamine, and other substrates.
Product analysis revealed that CDA treatment increased the deacetylation degree (DD) of natural chitin to 83%, surpassing that of commercial chitosan. Therefore, CDA demonstrates significant potential as an efficient deacetylation tool for natural chitin and chitooligosaccharides, highlighting its applicability in the biorefining of natural polysaccharides.
几丁质在海洋环境中含量丰富，在转化和利用方面面临重大挑战。从中国北海的 根际分离出一株具有显著几丁质脱乙酰化能力的菌株T22.7.1。16S rDNA序列比较分析表明，新分离菌株与CSLK01 - 03的序列相似性最高（99.79%），其次是DSM 43338、JC435和10bc312（分别为98.97%、98.81%和98.83%）。随后的基因组测序和系统发育分析证实菌株T22.7.1属于 物种。然而，进一步的分类学特征鉴定表明菌株T22.7.1是不同于CSLK01 - 03的 新型模式菌株。
本研究完善了 的分类学描述，并研究了其在将几丁质转化为壳聚糖中的应用。对菌株T22.7.1的几丁质脱乙酰酶（CDA）活性进行了优化，并从发酵产物中分离纯化了该酶。
通过优化，菌株T22.7.1的CDA活性达到287.02 U/mL，比原始酶活性（8.0 U/mL）高34.88倍。天然CDA酶的纯化因子为31.83，酶溶液的比活性达到1200.33 U/mg。CDA表现出良好的pH和温度适应性及稳定性，以及广泛的底物适应性，能有效使几丁质、壳寡糖、N - 乙酰葡糖胺等底物脱乙酰化。
产物分析表明，CDA处理使天然几丁质的脱乙酰度（DD）提高到83%，超过了商业壳聚糖。因此，CDA作为天然几丁质和壳寡糖的高效脱乙酰化工具具有巨大潜力，突出了其在天然多糖生物精炼中的适用性。
