The progressive substitution of petroleum-based polymers, such as polyethylene, polyvinylchloride, or polyethylene terephtalate, by so-called bioplastics facilitated the development and production of many new materials. The continuously refined properties of bioplastic compounds and their blends enable various applications. With growing production and utilization of bioplastic products, these materials are increasingly discarded into the environment. Although many of these materials are labeled biodegradable, there is limited information about their degradability under environmental conditions. We tested the enzymatic degradability of five bioplastic compounds with the rapid pH-Stat titration assay at environmentally relevant seawater temperatures between 5 and 30°C and pH 8.2. These plastics, issued from the European Horizon 2020 Project ´Bioplastics Europe´, are based on polylactic acid (PLA), polybutylene succinate (PBS), and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV). Suspensions of microparticles (< 200 µm) were incubated with each of the three hydrolytic enzymes, protease, lipase, and esterase. A PLA-based compound blended with polybutylene adipate terephthalate (PBAT) showed the highest hydrolysis rate of 30 nmol·min^-1 when incubated with lipase at 30°C. All other materials showed low hydrolysis rates of less than 10 nmol·min^-1. Below 20°C, hydrolysis almost ceased. Plate clearing assays with the same enzymes at 37°C and pH 5 and pH 8, respectively, largely confirmed the results of the pH-Stat titration assays. Our findings indicate that there is a potential degradation of most of the materials with at least one of these hydrolytic enzymes. Nonetheless, the rate of enzymatic degradation under environmentally relevant conditions is low, which indicates only a marginal degradability of bioplastics in the marine environment.

所谓的生物塑料逐渐取代石油基聚合物，如聚乙烯、聚氯乙烯或聚对苯二甲酸乙二醇酯，促进了许多新材料的开发和生产。生物塑料化合物及其混合物的不断改进的特性使各种应用成为可能。随着生物塑料产品的生产和利用不断增长，这些材料越来越多地被丢弃到环境中。尽管这些材料中的许多都被标记为可生物降解的，但关于它们在环境条件下的降解性的信息有限。我们在 5 至 30°C 和 pH 8.2 的环境相关海水温度下，使用快速 pH-Stat 滴定法测试了五种生物塑料化合物的酶降解性。这些塑料，由欧洲地平线 2020 项目“欧洲生物塑料”发布，基于聚乳酸 (PLA)、聚丁二酸丁二醇酯 (PBS) 和聚(羟基丁酸酯-共羟基戊酸酯) (PHBV)。将微粒悬浮液 (< 200 µm) 与三种水解酶、蛋白酶、脂肪酶和酯酶中的每一种一起孵育。与聚己二酸对苯二甲酸丁二醇酯 (PBAT) 共混的 PLA 基化合物的水解速率最高，为 30 nmol·min在 30°C 与脂肪酶一起孵育时为^{-1 。}所有其他材料都显示出低于 10 nmol·min ^-1的低水解速率。低于 20°C，水解几乎停止。分别在 37°C 和 pH 5 和 pH 8 下使用相同酶进行的板清除测定在很大程度上证实了 pH-Stat 滴定测定的结果。我们的研究结果表明，大多数材料可能会被这些水解酶中的至少一种降解。尽管如此，在环境相关条件下的酶降解率很低，这表明生物塑料在海洋环境中的降解能力有限。