Figure 2.

Quantification of H₂O₂ levels in non-inoculated culture media over time. (a) A standard curve was generated using stabilized H₂O₂ to quantify the H₂O₂ concentration in the media samples. (b) The concentration of H₂O₂ in non-inoculated YES and YEP culture media containing 15% or 1% carbon sources and initially supplemented to 30 mM H₂O₂ was monitored every 24 h for three days. The H₂O₂ concentration declined slowly over time in the YES media, the 1% peptone YEP media, and the water control, but plummeted sharply in YEP medium with 15% peptone (82.8% reduction in 72 h). This indicates that peptone molecules can potentially react with or inactivate H₂O₂.