Soil microorganisms play important roles in nitrogen cycling within forest ecosystems. Current research has revealed that a wider variety of microorganisms, with unexpected diversity in their functions and phylogenies, are involved in the nitrogen cycle than previously thought, including nitrogen-fixing bacteria, ammonia-oxidizing bacteria and archaea, heterotrophic nitrifying microorganisms, a...

We evaluated the regional distributions of six nitrogen (N2)-fixing bacteria in the North Pacific Ocean using quantitative polymerase chain reaction amplification of planktonic nifH genes. Samples were collected on four oceanographic research cruises between March 2002 and May 2005 that spanned a latitudinal range from 12uS and 54uN between 152uW and 170uW. Samples were collected throughout the...

Purple sulfur bacteria are photosynthetic, anaerobic microorganisms that fix carbon dioxide using hydrogen sulfide as an electron donor; many are also nitrogen fixers. Because of t h e ~ r requirements for sulfide or orgamc carbon as electron donors in anoxygenic photosynthesis, these bacteria are generally thought to be l im~ted to shallow, organic-nch, anoxic environments such as subtidal mar...

Over the last several decades, there have been a large number of studies done on the genetics, biochemistry, physiology, ecology, and agronomics of the bacteria forming nitrogen-fixing symbioses with legumes. These bacteria, collectively referred to as the rhizobia, are taxonomically and physiologically diverse members of the a and b subclasses of the Proteobacteria, and mostly comprise members...

To establish compatible rhizobial-legume symbioses, plant roots support bacterial infection via host-derived infection threads (ITs). Here, we report the requirement of plant flotillin-like genes (FLOTs) in Sinorhizobium meliloti infection of its host legume Medicago truncatula. Flotillins in other organisms have roles in viral pathogenesis, endocytosis, and membrane shaping. We identified seve...

TonB-dependent receptors (TBDRs) allow Gram-negative bacteria to uptake scarce resources from competitive environments with very high affinity. Early reports on TBDRs focused on the uptake of siderophore-iron complexes but recent studies have showed that the spectrum of ligands includes sugars, vitamins, heme, and other non-ferrous cations. To investigate the possible roles of TBDRs in nitrogen...

Nitrogen is an essential plant nutrient, widely applied as N-fertilizer to improve yield of agriculturally important crops. An interesting alternative to avoid or reduce the use of N-fertilizers could be the exploitation of plant growth-promoting bacteria (PGPB), capable of enhancing growth and yield of many plant species, several of agronomic and ecological significance. PGPB belong to diverse...

Endophytic nitrogen fixing bacteria were isolated from the leaves, stems and roots of industrial variety (cv. U-Thong 3; UT3), wild and chewing sugarcane plants grown for 6 weeks in nitrogen (N)-free sand. Eighty nine isolates of endophytic bacteria were obtained on N-free agar. An acetylene reduction assay (ARA) detected nitrogenase activity in all 89 isolates. Three isolates from the chewing ...

Abstract The community structure of nitrogen-fixing endophytic bacteria associated with roots of three varieties, Oryza sativa cv. Sprice and cv. Koshihikari and line NERICA 5 (an interspecific hybrid between O. sativa and O. glaberrima) was analyzed using culture-independent molecular techniques. A segment of nifH gene was amplified from crude rice root DNA, cloned to construct nifH library an...

The co-inoculation of mulberry with phosphate solubilizing micro-organisms, nitrogen fixing bacteria and arbuscular mycorrhiza has influenced its macronutrient uptake through leaf. The data revealed that maximum nitrogen (484.12 kg /ha) , phosphorus (59.83 kg /ha) and potassium (244.61 kg/ha) uptake through leaf has taken place due to co-inoculation treatments as compared to the un inoculated t...