title: Wavelength-normalized spectroscopic analysis ofStaphylococcus aureusandPseudomonas aeruginosagrowth rates.
abstract: Optical density (OD) measurements are the standard approach used in microbiology for characterizing bacteria concentrations in culture media. OD is based on measuring the optical absorbance of a sample at a single wavelength, and any error will propagate through all calculations, leading to reproducibility issues. Here, we use the conventional OD technique to measure the growth rates of two different species of bacteria,Pseudomonas aeruginosaandStaphylococcus aureus.The same samples are also analyzed over the entire UV-Vis wavelength spectrum, allowing a distinctly different strategy for data analysis to be performed. Specifically, instead of only analyzing a single wavelength, a multi-wavelength normalization process is implemented. When the OD method is used, the detected signal does not follow the log growth curve. In contrast, the multi-wavelength normalization process minimizes the impact of bacteria byproducts and environmental noise on the signal, thereby accurately quantifying growth rates with high fidelity at low concentrations.
authors.affiliation: Department of Biomedical Engineering, University of Southern California, 3651 Watt Way, Los Angeles, CA 90089, USA.
authors.forename: Samantha E
authors.initials: SE
authors.lastname: McBirney
authors.affiliation: School of Pharmacy, University of Southern California, 1985 Zonal Avenue, CA 90089, USA.
authors.forename: Kristy
authors.initials: K
authors.lastname: Trinh
authors.affiliation: School of Pharmacy, University of Southern California, 1985 Zonal Avenue, CA 90089, USA.
authors.forename: Annie
authors.initials: A
authors.lastname: Wong-Beringer
authors.affiliation: Department of Biomedical Engineering, University of Southern California, 3651 Watt Way, Los Angeles, CA 90089, USA; Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, 3651 Watt Way, Los Angeles, CA 90089, USA.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Armani
keywords: (120.1880) Detection; (170.1530) Cell analysis; (300.6550) Spectroscopy, visible