Physiology of nitrogen fixation by Aerobacter aerogenes.

Skinner (1928) tested 23 strains of Bacteriumn aerogenes (Aerobacter aerogenes) and reported that two, and possibly a third, assimilated gaseous nitrogen when cultured in liquid medium, a claim confirmed 27 years later by Hamilton and Wilson (1955) using the N" isotopic method. Their experiments indicated that A. aerogenes incorporated significant amounts of tracer and that anaerobically, in a well buffered medium, fixed sufficient nitrogen to be measured by a semimicro-Kjeldahl method. We have extended this result to a total of 7 strains. Jensen (1956) independently obtained fixation by 2 of 3 strains of the organism isolated from water. For obvious reasons the numerous studies that deal with the physiology of the aerobacter have not included investigations concerned with this only recently established characteristic. The work reported in this paper deals with this aspect of the physiology of this organism.