Dept. of Civil, Chemical, Environmental and Material Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy.
Dept. of Civil, Chemical, Environmental and Material Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy.
Sci Total Environ. 2023 Nov 10;898:165485. doi: 10.1016/j.scitotenv.2023.165485. Epub 2023 Jul 11.
The use of biodegradable plastics is constantly raising, increasing the likeliness for these polymers to end up in the environment. Environmental applications foreseeing the intentional release of biodegradable plastics have been also recently proposed, e.g., for polyhydroxyalkanoates (PHAs) acting as slow hydrogen releasing compounds to stimulate microbial reductive dehalogenation processes. However, the effects of their release into the environment on the ecosystems still need to be thoroughly explored. In this work, the use of PHAs to enhance the microbial reductive dechlorination of polychlorobiphenyls (PCBs) and their impact on the metabolic and compositional features of the resident microbial community have been investigated in laboratory microcosms of a polluted marine sediment from Mar Piccolo (Taranto, Italy), and compared with recent findings on a different contaminated marine sediment from Pialassa della Baiona (Ravenna, Italy). A decreased biostimulation efficiency of PHAs on PCBs reductive dechlorination was observed in the sediment from Mar Piccolo, with respect to the sediment from Pialassa della Baiona, suggesting that the sediments' physical-chemical characteristics and/or the biodiversity and composition of its microbial community might play a key role in determining the outcome of this biostimulation strategy. Regardless of the sediment origin, PHAs were found to have a specific and pervasive effect on the sediment microbial community, reducing its biodiversity, defining a newly arranged microbial core of primary degraders and consequently affecting, in a site-specific way, the abundance of subdominant bacteria, possibly cross-feeders. Such potential to dramatically change the structure of autochthonous microbial communities should be carefully considered, since it might have secondary effects, e.g., on the natural biogeochemical cycles.
可生物降解塑料的使用不断增加，这些聚合物最终进入环境的可能性也在增加。最近还提出了一些环境应用，旨在故意释放可生物降解塑料，例如聚羟基烷酸酯 (PHA) 作为缓慢释放氢的化合物，以刺激微生物的还原脱卤过程。然而，它们释放到环境中对生态系统的影响仍需要彻底探索。在这项工作中，使用 PHAs 来增强多氯联苯 (PCBs) 的微生物还原脱氯作用，以及它们对污染海洋沉积物中居民微生物群落的代谢和组成特征的影响，在来自意大利塔兰托的 Mar Piccolo 的污染海洋沉积物的实验室微宇宙中进行了研究，并与来自意大利拉文纳的 Pialassa della Baiona 的不同污染海洋沉积物的最新发现进行了比较。与来自 Pialassa della Baiona 的沉积物相比，Mar Piccolo 沉积物中 PHAs 对 PCB 还原脱氯的生物刺激效率降低，这表明沉积物的物理化学特性和/或其微生物群落的生物多样性和组成可能在决定这种生物刺激策略的结果方面发挥关键作用。无论沉积物的来源如何，PHA 都被发现对沉积物微生物群落具有特定且普遍的影响，降低了其生物多样性，定义了一个新的主要降解菌核心，从而以特定于地点的方式影响亚优势细菌（可能是交叉喂养者）的丰度。这种剧烈改变本土微生物群落结构的潜力应该仔细考虑，因为它可能会产生二次影响，例如对自然生物地球化学循环的影响。
