The focus of our collaborative research program is the identification
and characterization of nif and related regulatory genes of Acetobacte
r diazotrophicus in order to understand what factors influence nitroge
n fixation in this unique diazotroph. To date, the following genes hav
e been isolated from genomic libraries and are being analyzed: nifHDK,
nifA, nifB, nifV, nifE and ntrBC. In addition, Nif mutants have been
constructed by insertional mutagenesis. These mutants are currently be
ing used in inoculation experiments of sterile sugarcane plants to det
ermine whether nitrogen fixed by A. diazotrophicus is significant for
plant nutrition. (C) 1997 Elsevier Science Ltd.