Abstract
A bacterium, isolated from human saliva, produced carbon monoxide (CO) when cultured in nutrient broth containing hemin or hemoglobin. The production of CO was detected by gas chromatography, and confirmed by gas chromatography-mass spectrometry and spectrophotometry which revealed an absorption spectrum of CO-hemoglobin. The isolated bacterium was identified as a strain of Proteus vulgaris. Survey of 4 IFO strains of P. vulgaris, 1 IFO strain of P. mirabilis and 2 IFO strains of Morganella morganii (received as P. morganii) showed that all the 7 strains had the ability to produce CO. They produced detectable amounts of CO when cultured in a glucose-peptone medium or in the nutrient broth without the addition of heme compound, and the CO production was distinctly enhanced by the addition of hemin. Morganella morganii IFO 3168, the most active CO producer among the strains tested, produced about 2μmol of CO in the absence of hemin and 6μmol of CO in the presence of 3μmol of hemin. The result suggests that CO production by the Morganella strain is different from the CO production by mammalian tissues where 1mol of protoheme is degraded to 1mol each of CO and biliverdin.
