Analysis of high-molecular weight polyethylene glycol degradation by Pseudomonas sp.

• Comprehensive PEG biodegradation study by combing SEC-MALS-VISC and MALDI-TOF MS • Pseudomonas sp. grows on PEG from 6,000 to 40,000 g mol −1 as the sole carbon source • Rapid growth on PEG 6,000 g mol −1 indicates internal degradation • Growth on PEG 20,000 and 40,000 g mol −1 is increasingly delayed • PEG metabolization occurs at the hydroxyethylene terminus Polyethylene glycol (PEG) has widespread applications in pharmacy, medicine, and cosmetics, but its biological degradation is not completely understood, especially because of the complex analytics required for determining changes in molar mass and side or end groups, respectively. Here, we describe the activity of Pseudomonas sp. on PEG with molar masses of 6,000, 20,000 and 40,000 g mol −1 . The molar mass distribution after degradation was analyzed by size-exclusion chromatography (SEC) with different detection methods as well as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and the differences between the results demonstrated. Further, the influence of the complex bacterial cultivation medium on analysis results was discussed. MALDI-TOF MS analysis revealed hydroxyethylene end-units on the PEG-terminus after bacterial degradation providing hints on the bacterial degradation pathway via end-unit scissioning followed by oxidation of the cleaved unit.