OPTICAL FIBER-BASED IN-SITU SPECTROSCOPY OF PIGMENTED SINGLE COLONIES

We have adapted a commercially available fiber-optic spectroradiometer with diode array detection to record reflection and absorption spectr a from single, 1-mm-diameter bacterial colonies. A careful assessment of the performance of the spectroradiometer for this application is re ported, In a model study employing colonies from various phototrophic bacteria, we show that the reflectance spectra are reliable within the range of 450 to 820 nm, whereas the transmission spectra yield accura te peak intensities and absorption maxima from 400 to 900 nm, For scre ening of populations of about 10(4) colonies, fiber-optic transmission spectroscopy provides an attractive and inexpensive alternative to pr esent techniques based on charge-coupled device imaging technology.