Geometrical-optics approach to measure the optical density of bacterial cultures using a LED-based photometer

Massimiliano Lucidi; Marco Marsan; Francesco Pudda; Mattia Pirolo; Emanuela Frangipani; Paolo Visca; Gabriella Cincotti

doi:10.1364/BOE.10.005600

Geometrical-optics approach to measure the optical density of bacterial cultures using a LED-based photometer

Biomed Opt Express. 2019 Oct 8;10(11):5600-5610. doi: 10.1364/BOE.10.005600. eCollection 2019 Nov 1.

Authors

Massimiliano Lucidi¹, Marco Marsan¹, Francesco Pudda¹, Mattia Pirolo², Emanuela Frangipani³, Paolo Visca², Gabriella Cincotti¹

Affiliations

¹ Engineering Department, University Roma Tre, via Vito Volterra 62, 00146 Rome, Italy.
² Department of Science, University Roma Tre, viale Marconi 446, 00146 Rome, Italy.
³ Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, Italy.

Abstract

We develop a suitable geometrical-optics approach and demonstrate that it is possible to measure the optical density (OD) of bacterial cultures using a light emitting diode (LED)-based photometer. We measure both attenuation and spot-size variation, and we compensate for diffraction and stray-light impairment related to the incoherent source and large detection area. The approach is validated for different concentrations of two bacterial species, Escherichia coli and Staphylococcus aureus, that present different shapes and clustering organization.