Molecular phylogeny of two Aliinostoc isolates from a paddy field

Rice has been the staple food of the Iranian population, and nitrogen availability is usually a limiting factor to high yields in paddy fields. Among the nitrogen-fixing microorganisms, cyanobacteria play a major role in the nitrogen fixation process. In the present work, two nitrogen-fixing cyanobacteria isolated from a paddy field in Golestan Province, Iran, were analyzed using a polyphasic approach including morphological and molecular analyses. Complete 16S rRNA gene sequences were analyzed phylogenetically coupled with the 16S-23S internal transcribed spacer (ITS) secondary structures. Sequences of the rbc L, tuf A, psb A and rpo C1 genes were investigated as additional determinants. The 16S rRNA phylogenetic analysis grouped the new isolates into the cluster of the genus Aliinostoc , which was supported by rbc L, tuf A, psb A and rpo C1 phylogenetic trees. The 16S-23S ITS-folded structures of the D1-D1′ and Box-B regions differentiated the isolates from published Aliinostoc . These findings contribute to extend the knowledge on biodiversity of the nitrogen-fixing genus Aliinostoc sparsely characterized in Iran.