Sinorhizobium nodules in alfalfa roots.
(Image from A. Becker & E.G. Biondi, University of Florence)
In a study published May 15, 2012 in BMC Microbiology, researchers from Florida State University conducted a comparative genomic study using the DOE JGI’s Integrated Microbial Genomes (IMG) portal to look for open reading frames (ORFs) -- the part of a gene that codes for a protein -- in S. meliloti that are involved in nitrogen fixation.
The team conducted their search by comparing ORFs from nitrogen-fixing bacteria with those from closely-related but non-nitrogen-fixing bacteria such as plant or mammalian pathogens. They reported that their comparative genomics method “rediscovered” 19 ORFs that had previously been shown to be important for nodulation and/or nitrogen fixation. They were also able to identify nine S. meliloti ORFs that may play a role in forming a symbiotic relationship between bacterium and plant host. “The comparative genomics method described above might be very effective for identifying factors… that have not yet been studied by classical transposon mutagenesis screens,” they wrote.