The diversity of 71 rhizobial strains belonging to the genus Ensifer, isolated from root nodules of woody legumes growing in southern Ethiopia, was studied using multilocus sequence analysis (MLSA) and phenotypic approaches. Phylogenetic analyses based on core genes revealed that 43 strains were clustered in seven distinct and consistent positions (genospecies I-VII), while another 25 strains w...

Nitrogen availability in dead wood is highly restricted and associations with N-fixing bacteria are thought to enable wood-decaying fungi to meet their nitrogen requirements for vegetative and generative growth. We assessed the diversity of nifH (dinitrogenase reductase) genes in dead wood of the common temperate tree species Fagus sylvatica and Picea abies from differently managed forest plots...

The association of wild grasses with diazotrophic bacteria in Brazilian biomes is poorly understood. The isolation and characterization of bacteria associated with wild grasses can contribute to understand the diazotrophic ecology as well as to identify bacteria with biotechnological applications. In this study, we isolated and characterized diazotrophic bacterial isolates from Oryza glumaepatu...

Arid regions pose a serious problem for crop production by suppressing plant growth. The use of plant growth promoting rhizobacteria (PGPR) as bioinoculant may be promising to enhance the crop yield in arid conditions. In the present investigation, four strains of cultivable bacteria associated with the rhizosphere of Saccharum L. grown in arid region were isolated using N-free media. Assessmen...

In many environments, biological nitrogen fixation can alleviate nitrogen limitation. The high rates of N(2) fixation often observed in cyanobacterial mats suggest that N(2) fixation may be an important source of N. In this study, organisms expressing nifH were identified in a Lyngbya sp.- and two Microcoleus chthonoplastes-dominated cyanobacterial mats. The pattern of nitrogenase activity was ...

A cultivation-independent approach was used to identify potentially nitrogen-fixing endophytes in seven sweet potato varieties collected in Uganda and Kenya. Nitrogenase reductase genes (nifH) were amplified by PCR, and amplicons were cloned in Escherichia coli. Clones were grouped by restriction fragment length polymorphism analysis, and representative nifH genes were sequenced. The resulting ...

Nitrogen (N) cycling microbial communities in marine sediments are extremely diverse, and it is unknown whether this diversity reflects extensive functional redundancy. Sedimentary denitrifiers remove significant amounts of N from the coastal ocean and diazotrophs are typically regarded as inconsequential. Recently, N fixation has been shown to be a potentially important source of N in estuarin...

Coevolution of the symbiotic systems of termites is investigated by comparing the phylogeny of the gut microorganisms among diverse termites. Some major constituents of the gut community, such as Treponema-like spirochetes and the Bacteroides group, showed complex evolutionary history due to their multiple phylogenetic positions. Groups of methanogenic archaea in the guts are distinct between l...