APPLICATIONS OF IMAGING SPECTROSCOPY IN MOLECULAR-BIOLOGY .2. COLONY SCREENING BASED ON ABSORPTION-SPECTRA

Digital imaging spectroscopy has been used to obtain the grayscale spectrum of colored bacterial colonies directly from petri dishes. Up to 500 individual colony spectra can be simultaneously recorded and processed from a single plate. Spectra can be obtained in the visible to near infrared region (400nm—900nm) with lOnm resolution. Instrument response is normalized through run-time radiometric calibration such that each grayscale spectrum can be converted to the ground-state absorption spectrum of the colony. In this study, mutants of the photosynthetic bacterium Rhodobacter capsulatus have been differentiated by the absorption spectra of their pigment-protein complexes. This imaging technique is applicable to chro-mogenic systems in which colony and/or media color (e.g. indicator plates) provides a quantitative indicator of gene expression. © 1990 Nature Publishing Group.