Figure 2.

Artificial UV aging accelerated the rate of biodegradation of oxo-LDPE compared with LDPE as a result of changes in molecular weight. (a) CO₂ production from R. rhodochrous (n = 5) grown with no supplied carbon (open black diamond) on unaged LDPE (open red circle) and unaged oxo-LDPE (open blue square) compared to 450 h UV-irradiated plastic of both LDPE (solid red circles) or oxo-LDPE (solid blue squares). UV exposure of oxo-LDPE significantly affected CO₂ production (p < 0.001), while there was only a small increasing trend in CO₂ production between UV-treated LDPE and unaged plastics (p = 0.26). (b) The molecular weight (kDa) of LDPE (red open circles) and oxo-LDPE (blue solid squares), as measured by gel permeation chromatography, compared to UV exposure time (n = 3). (c) The concentration of CO₂ measured at 35 days for R. rhodochrous grown on LDPE (red) or oxo-LDPE (blue) after UV irradiation (n = 5, error bars represent standard error) compared to the molecular weight of the sample revealed a clear link between molecular weight and CO₂ production. The length of UV irradiation exposure is cited alongside each data point.