A new fermentative pseudomonad, Pseudomonas formicans, n. sp.

Only two of the many previously described species of the genus Pseudomonas wil grow and metabolize sugars under strictly anaerobic conditions. Certain others can make use of substitute hydrogen acceptors, such as nitrates or nitrites, but only Pseudomonas lindneri and Pseudomonas fermetas are truly fermentative organisms (Kluyver and Hoppenbrouwers, 1931; Kuhr, 1932). The former carries out an alcoholic fermentation similar to that of yeast, and the latter, now thought to be identical with Prote hydrophilus (Sanarelli, 1891) and perhaps better called Pseudomonas hydrophila (Stanier, 1943; Miles and Miles, 1951), has a butylene glycol or Aerobacter-type of fermentation. The anaerobic metabolism of these two organisms is so distinctive that Kluyver and van Niel (1936) suggested that they be assigned two separate genera, called Zymomonas and Aeromonas, respectively. In 1942 Doudoroff showed that certain facultatively anaerobic luminous bacteria of the genera Photobacterium and Achromobacter possessed a mixed acid type of fermentation similar to that of Escherichia coli. Since there exists evidence that these luminous bacteria are polarly flagellated (Molisch, 1912; Breed et al., 1948; and Johnson et al., 1943), Duodoroff's observations suggested that an E. coli type of fermentation might appear among other polar flagellates as well.