Fig. 3.

Relative change in initial and final concentrations of polypropylene glycols (PPGs) and C₈ alkyl polyethoxylates (AEOs) in surfactant amended cell cultures between inoculation (t₀) and stationary phase (t_s, 51 h). a The sum of all PPG and C₈ AEO polyglycol species. b Relative change in each individual ethoxylate/propoxylate. Error bars correspond to standard deviations between triplicate measurements, and statistical significance for biotic cells (p < 0.1) is denoted by (*) compared to abiotic controls only and (**) compared to both killed and abiotic controls