ACIB - Austrian Centre of Industrial Biotechnology GmbH , Konrad Lorenz Strasse 20, 3430 Tulln an der Donau, Austria.
BASF SE , Carl-Bosch-Strasse 38, 67056 Ludwigshafen am Rhein, Germany.
Environ Sci Technol. 2017 Apr 18;51(8):4596-4605. doi: 10.1021/acs.est.7b00062. Epub 2017 Apr 7.
Water-soluble polyesters are used in a range of applications today and enter wastewater treatment plants after product utilization. However, little is known about extracellular enzymes and aquatic microorganisms involved in polyester biodegradation and mineralization. In this study, structurally different ionic phthalic acid based polyesters (the number-average molecular weights (M) 1770 to 10 000 g/mol and semi crystalline with crystallinity below 1%) were synthesized in various combinations. Typical wastewater microorganisms like Pseudomonas sp. were chosen for in-silico screening toward polyester hydrolyzing enzymes. Based on the in-silico search, a cutinase from Pseudomonas pseudoalcaligenes (PpCutA) and a putative lipase from Pseudomonas pelagia (PpelaLip) were identified. The enzymes PpCutA and PpelaLip were demonstrated to hydrolyze all structurally different polyesters. Activities on all the polyesters were also confirmed with the strains P. pseudoalcaligenes and P. pelagia. Parameters identified to enhance hydrolysis included increased water solubility and polyester hydrophilicity as well as shorter diol chain lengths. For example, polyesters containing 1,2-ethanediol were hydrolyzed faster than polyesters containing 1,8-octanediol. Interestingly, the same trend was observed in biodegradation experiments. This information is important to gain a better mechanistic understanding of biodegradation processes of polyesters in WWTPs where the extracellular enzymatic hydrolysis seems to be the limiting step.
水溶性聚酯在当今有广泛的应用，在产品使用后会进入废水处理厂。然而，对于参与聚酯生物降解和矿化的细胞外酶和水生微生物知之甚少。在这项研究中，合成了不同结构的离子邻苯二甲酸基聚酯（数均分子量（M）为 1770 至 10000 g/mol，半结晶，结晶度低于 1%），并进行了各种组合。选择了典型的废水微生物，如假单胞菌，用于聚酯水解酶的计算机筛选。根据计算机搜索，从假单胞菌假产碱杆菌（PpCutA）和假栖热菌（PpelaLip）中鉴定出一种角质酶和一种假定的脂肪酶。PpCutA 和 PpelaLip 酶被证明可以水解所有结构不同的聚酯。假单胞菌假产碱杆菌和假栖热菌也证实了这些酶对所有聚酯的活性。确定的增强水解的参数包括增加水溶性和聚酯亲水性以及缩短二醇链长。例如，含有 1,2-乙二醇的聚酯比含有 1,8-辛二醇的聚酯水解速度更快。有趣的是，在生物降解实验中也观察到了同样的趋势。这些信息对于更好地了解 WWTP 中聚酯生物降解过程的机制非常重要，因为细胞外酶水解似乎是限制步骤。
