Barbara Reinhold-Hurek

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Ammonia-oxidizing archaea (AOA) play an important role in nitrification and many studies exploit their amoA genes as marker for their diversity and abundance. We present an archaeal amoA consensus phylogeny based on all publicly available sequences (status June 2010) and provide evidence for the diversification of AOA into four previously recognized(More)
As current research activities have focused on symbiotic or parasitic plant-microbe interactions, other types of associations between plants and microorganisms are often overlooked. Endophytic bacteria colonize inner host tissues, sometimes in high numbers, without damaging the host or eliciting strong defense responses. Unlike endosymbionts they are not(More)
The invasive properties of Azoarcus sp. strain BH72, an endorhizospheric isolate of Kallar grass, on gnotobiotically grown seedlings of Oryza sativa IR36 and Leptochloa fusca (L.) Kunth were studied. Additionally, Azoarcus spp. were localized in roots of field-grown Kallar grass. To facilitate localization and to assure identity of bacteria, genetically(More)
Six closely related N2-fixing bacterial strains were isolated from surface-sterilized roots and stems of four different rice varieties. The strains were identified as Serratia marcescens by 16S rRNA gene analysis. One strain, IRBG500, chosen for further analysis showed acetylene reduction activity (ARA) only when inoculated into media containing low levels(More)
Azoarcus sp. strain BH72, a mutualistic endophyte of rice and other grasses, is of agrobiotechnological interest because it supplies biologically fixed nitrogen to its host and colonizes plants in remarkably high numbers without eliciting disease symptoms. The complete genome sequence is 4,376,040-bp long and contains 3,992 predicted protein-coding(More)
Roots are the primary site of interaction between plants and microorganisms. To meet food demands in changing climates, improved yields and stress resistance are increasingly important, stimulating efforts to identify factors that affect plant productivity. The role of bacterial endophytes that reside inside plants remains largely unexplored, because(More)
The extent to which the N2-fixing bacterial endophyte Azoarcus sp. strain BH72 in the rhizosphere of Kallar grass can provide fixed nitrogen to the plant was assessed by evaluating inoculated plants grown in the greenhouse and uninoculated plants taken from the natural environment. The inoculum consisted of either wild-type bacteria or nifK- mutant strain(More)
N2-fixing bacteria such as Azoarcus spp., Herbaspirillum spp, and Acetobacter diazotrophicus can infect the interior of gramineous plants without causing symptoms of plant disease but do not survive in soil. Like phytopathogens, they can penetrate into central tissues and spread systemically. There is no evidence for an endosymbiosis in living plant cells;(More)
Nitrogenase is a functionally constant protein catalyzing N2 reduction, which is found in many phylogenetic lineages of Archaea and Bacteria. A phylogenetic analysis of nif genes may provide insights into the evolution of the bacterial genomes. Moreover, it may be used to study diazotrophic communities, when classical isolation techniques may fail to detect(More)
Adherence of bacteria to eukaryotic cells is essential for the initiation of infection in many animal and human pathogens, e.g. Neisseria gonorrhoeae and Pseudomonas aeruginosa. Adhesion-mediating type IV pili, filamentous surface appendages formed by pilin subunits, are crucial virulence factors. Here, we report that type IV pilus-dependent adhesion is(More)