Studies on Acetobacter diazotrophicus : Analysis of Nif and Related Genes and Contributions to Sugarcane Nutrition

The recent identification of A. diazotrophicus as an endophyte of sugarcane raises the possibility of a new classification of symbiosis, one in which, like the Rhizobium/Legume symbiosis, the plant partner supplies photosynthate to support bacterial nitrogen fixation and the bacterium provides fixed nitrogen for plant growth (Cavalcante, Dobereiner 1988). Our goals in studying A. diazotrophicus were to analyze the bacterial genes responsible for nitrogen fixation and its regulation and to establish whether A. diazotrophicus colonizing sterile sugarcane plants contributes significant fixed nitrogen to the plant to enhance its growth in N-limiting growth conditions.