Abstract

Specific features of the enzymatic degradation of chitosan with depolymerization degrees (DD) of 85 and 50% by microbial chitinases and chitosanases were studied in terms of the conversion degree, molecular-weight distribution (MWD), and antimicrobial activity of the generated reaction products. The enzyme complex produced by the strain B. thuringiensis B-387, which is characterized by high chitosanase production (>4.5 U mL^–1), degraded the polymer to soluble, low molecular weight chitooligosaccharides (CHOs, M_w ≤ 2 kDa), along with a minor yield (~5%) of alkali-precipitated oligochitosans (M_w 2–16 kDa). The hydrolytic complexes produced by B. atrophaeus IB-33-1 and Cohnella sp. IB-P192, which mainly comprise chitinases (0.3–0.5 U mL^–1), demonstrated the lowest rate and degree of chitosan (DD 85%) hydrolysis. The selection of an enzyme : substrate ratio in the range of 2–5 units/g (based on chitosanase) made it possible to reduce the hydrolysis depth of the initial polymer and to increase the yield of oligochitosans with a M_w of ~15–17 kDa to 30% for chitosan (DD 85%) depolymerization by the enzyme complex from B. thuringiensis B-387. The decrease in the bactericidal and fungicidal effect of the oligomers that formed during the destruction of chitosan with varying deacetylation degrees (DD 85% and 50%) by enzyme complexes displaying high chitosanase activity was, as a rule, more distinct than that achieved with the use of chitinases. However, in some cases, there were both nonspecific and specific enhancements of the antimicrobial action of hydrolytic products in comparison with the initial polymer, which was determined by individual sensitivity of bacterial and micromycetes strains.

中文翻译：

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微生物几丁质酶和壳聚糖酶解聚壳聚糖对生成的壳寡聚体的抗菌活性的影响

摘要

研究了微生物几丁质酶和壳聚糖酶对解聚度 (DD) 为 85% 和 50% 的壳聚糖的酶促降解的转化率、分子量分布 (MWD) 和生成的反应产物的抗菌活性的具体特征。苏云金芽孢杆菌B-387菌株产生的酶复合物，其特点是壳聚糖酶产量高 (>4.5 U mL ^–1 )，将聚合物降解为可溶性低分子量壳寡糖 (CHOs，M _w ≤ 2 kDa)，以及少量 (~5%) 的碱沉淀寡聚壳聚糖 (M _w 2–16 kDa)。B. atrophaeus IB-33-1 和Cohnella产生的水解复合物sp. IB-P192 主要包含几丁质酶 (0.3–0.5 U mL ^–1 )，显示出最低的壳聚糖 (DD 85%) 水解速率和程度。酶：底物比在 2–5 单位/g 范围内（基于壳聚糖酶）的选择可以降低初始聚合物的水解深度并提高 M _w约 15–的壳寡糖产量。17 kDa 至 30% 的壳聚糖 (DD 85%) 由来自苏云金芽孢杆菌的酶复合物解聚B-387。显示高壳聚糖酶活性的酶复合物破坏具有不同脱乙酰度（DD 85% 和 50%）的壳聚糖期间形成的低聚物的杀菌和杀真菌作用的降低通常比使用使用几丁质酶。然而，在某些情况下，与初始聚合物相比，水解产物的抗菌作用存在非特异性和特异性增强，这是由细菌和微菌菌株的个体敏感性决定的。