Biodegradation of water-soluble polymers by wastewater microorganisms

For water-soluble polymers (WSPs) that enter environmental systems at their end-of-life, biodegradability is a key functionality. We used respirometric laboratory tests to study the biodegradation of poly(amino acids), poly(ethylene glycol), and poly(vinyl alcohol. We varied key protocol steps of commonly used testing methods, which were originally established for small molecules, and tested for effects on WSP biodegradation such as avoiding aeration of the wastewater inoculate prior to WSP addition, WSP incubation with filter-sterilized wastewater prior to biodegradation testing, and lowering WSP concentration. Combining the above-mentioned protocol variations substantially affected the results of the biodegradation testing for the two poly(amino acids) tested herein (i.e., poly(lysine) and poly(aspartic acid)). Our study presents promising biodegradation dynamics for poly(amino acids) and highlights the importance, strengths, and limitations of respirometric laboratory methods for WSPs biodegradation testing. Sequencing was performed at the Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna under the project ID JMF-2311-02