Irradiation of Escherichia coli in the visible spectrum with a tunable organic-dye laser energy source.

Pulsed laser energy was shown to be effective in inhibiting the growth of Escherichia coli. The irradiation source was derived from a tunable organic-dye laser utilizing rhodamine 6G (590 plus or minus 5 nm) solutions as lasing media. The organisms, suspended in nutrient broth, were irradiated both with and without an exogenous photosensitizer. One photosensitizer (toluidine blue) did not appreciably alter the inhibitory effect observed. In the presence of acridine orange, however, some additional growth occurred.