Atanasova Nikolina, Paunova-Krasteva Tsvetelina, Kambourova Margarita, Boyadzhieva Ivanka
Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 26, 1113 Sofia, Bulgaria.
BioTech (Basel). 2023 Mar 14;12(1):23. doi: 10.3390/biotech12010023.
The tremendous problem with plastic waste accumulation has determined an interest in biodegradation by effective degraders and their enzymes, such as thermophilic enzymes, which are characterized by high catalytic rates, thermostability, and optimum temperatures close to the melting points of some plastics. In the present work, we report on the ability of a thermophilic lipase, by strain 7, to degrade Ɛ-polycaprolactone (PCL), as well as the enzyme purification, the characterization of its physicochemical properties, the product degradation, and its disruptive effect on the PCL surface. The pure enzyme showed the highest reported optimum temperature at 55 °C and a pH of 7.5, while its half-life at 60 °C was more than five hours. Its substrate specificity referred the enzyme to the subgroup of lipases in the esterase group. A strong inhibitory effect was observed by detergents, inhibitors, and Fe while Ca enhanced its activity. The monomer Ɛ-caprolactone was a main product of the enzyme degradation. Similar elution profiles of the products received after treatment with ultra-concentrate and pure enzyme were observed. The significant changes in PCL appearance comprising the formation of shallower or deeper in-folds were observed after a week of incubation. The valuable enzyme properties of the lipase from strain 7, which caused a comparatively quick degradation of PCL, suggests further possible exploration of the enzyme for effective and environment-friendly degradation of PCL wastes in the area of thermal basins, or in thermophilic remediation processes.
塑料垃圾堆积这一巨大问题引发了人们对利用高效降解菌及其酶进行生物降解的兴趣，比如嗜热酶，其特点是催化速率高、热稳定性好，且最适温度接近某些塑料的熔点。在本研究中，我们报告了菌株7产生的嗜热脂肪酶降解聚己内酯（PCL）的能力，以及该酶的纯化、理化性质表征、产物降解情况及其对PCL表面的破坏作用。纯酶的最高报道最适温度为55℃，最适pH为7.5，其在60℃的半衰期超过5小时。其底物特异性表明该酶属于酯酶组中脂肪酶的亚组。洗涤剂、抑制剂和铁对其有强烈抑制作用，而钙可增强其活性。单体ε-己内酯是该酶降解的主要产物。观察到用超浓缩物和纯酶处理后得到的产物具有相似的洗脱曲线。孵育一周后，观察到PCL外观发生了显著变化，包括形成了较浅或较深的褶皱。菌株7产生的脂肪酶具有宝贵的酶学性质，能相对快速地降解PCL，这表明在热盆地地区或嗜热修复过程中，进一步探索该酶用于有效且环境友好地降解PCL废物具有可能性。
