PT - JOURNAL ARTICLE AU - Ariel Hecht AU - Drew Endy AU - Marc Salit AU - Matthew S. Munson TI - When Wavelengths Collide: Bias in Cell Abundance Measurements due to Expressed Fluorescent Proteins AID - 10.1101/037010 DP - 2016 Jan 01 TA - bioRxiv PG - 037010 4099 - http://biorxiv.org/content/early/2016/01/22/037010.short 4100 - http://biorxiv.org/content/early/2016/01/22/037010.full AB - The abundance of bacteria in liquid culture is commonly inferred by measuring optical density at 600 nm. Red fluorescent proteins (RFP) can strongly absorb light at 600 nm. Increasing RFP expression can falsely inflate apparent cell density and lead to underestimations of mean per-cell fluorescence by up to 10%. Measuring optical density at 700 nm would allow estimation of cell abundance unaffected by the presence of nearly all fluorescent proteins.