Degradability of poly(ether-urethanes) and poly(ether-urethane)/acrylic hybrids by bacterial consortia of soil

Abstract

An enrichment culture strategy was used to obtain natural consortia from soil in order to study the biodegradability of poly(ether-urethanes) (PUE). PUE were synthesized with different aliphatic diisocyanate group, termed PUIPDI and PUHMDI. In addition, PUE/acrylic hybrids, termed PUH90:DEA10 and PUH70:DEA30 consisted of PUHMDI and increasing ratio of 2-(diethylamino)ethyl methacrylate (DEA) were tested. PUIPDI was biodeteriorated through urea-bond hydrolysis by a consortium dominated by Acinetobacter. A higher biodeterioration rate was demonstrated for PUHMDI, which exhibited large surface holes and a greater weight loss. The hydrolysis of ester-urethane bonds and the oxidation of soft-segment ether bonds were the key reactions identified, possibly by Acinetobacter, Mycobacterium, Sphingopyxis and Pseudomonas, which were present in this consortium. Diverse metabolic functions were also predicted. The addition of DEA favored the biodegradability of PUH:DEA hybrids demonstrated by the increased weight loss, swelling degree and the hydrolysis of DEA-ester bond. Urethane and ether bonds degradation were also detected. PUH:DEA hybrids selected even bacterial consortia, most likely by allowing better access to the nutrients. Pseudomonadaceae and Bradyrhizobiaceae families got relevance in these consortia and their outstanding features were cell mobility and quorum sensing. This work has provided a deeper insight into PUE biodegradation by proposing the chemical mechanisms, bacterial taxa and functions that could be implicated.