Light sensitivity of methanogenic archaebacteria.

Representatives of four families of methanogenic archaebacteria (archaea), Methanobacterium thermoautotrophicum delta H, Methanobacterium thermoautotrophicum Marburg, Methanosarcina acetivorans, Methanococcus voltae, and Methanomicrobium mobile, were found to be light sensitive. The facultative anaerobic eubacteria Escherichia coli and Salmonella typhimurium, however, were tolerant of light when grown anaerobically under identical light conditions. Interference filters were used to show that growth of the methanogens is inhibited by light in the blue end of the visible spectrum (370 to 430 nm).