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17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Session Details: Tuesday 29 November 2011 Plenary Session 3 0900 - 1030 Authors: Wayne G. Reeve 1 and Nikos Kyrpidis 2 1 Centre for Rhizobium Studies, School of Biological Sciences and Biotechnology, Murdoch University, South Street, Murdoch 6150, Australia. 2 DOE Joint Genome Institute
, Walnut Creek, CA, USA Presentation Title: The GEBA - Root Nodule Bacteria Community Sequencing Project Presentation Time: 0900 - 0930 Genome sequencing has revolutionized understanding of microorganisms and the roles they play in important processes such as pathogenesis, energy production, bioremediation, global nutrient cycles, and the origins, evolution, and diversity of life. However, there are significant gaps in microbial genome sequence availability especially associated with environmental genomics. The currently available microbe genome sequences show a highly biased phylogenetic distribution compared to the extent of microbial diversity known today. This bias has resulted in a major gap in our knowledge of microbial genome complexity and our understanding of the evolution, physiology, and metabolic capacity of microbes. There is a strong need for a large-scale systematic effort to sequence genomes to fill in genomic gaps in the tree of life. To this end the Genomic Encyclopedia of Bacteria and Archaea – Root Nodule Bacteria (GEBA-RNB) initiative at the Joint Genome Institute aims to sequence 100 RNB strains of commercial, genetic and ecological importance. This project will support the systematic sequence-based studies and understanding of the biogeographical effects on species evolution as well as the mechanisms of symbiotic nitrogen fixation by RNB. Shared genetic mechanisms between fungal and bacterial root endosymbioses exist and a detailed understanding of endosymbionts will be beneficial to drive bioenergy development from trees. The GEBA-RNB project is based on collaboration between JGI and an international consortium from 15 countries coordinated by the Centre for Rhizobium Studies at Murdoch University. 34 2011

17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Session Details: Tuesday 29 November 2011 Plenary Session 3 0900 - 1030 Authors: Hao Ding 1 , Cynthia Yip 1 , Barney A. Geddes 2 , Ivan J. Oresnik 2 , and Michael F. Hynes 1 1 University of Calgary, Biological Sciences, Calgary AB, Canada T2N 1N4 2 University of Manitoba, Microbiology, Winnipeg MB, Canada R3T 2N2 Presentation Title: Glycerol utilization by Rhizobium leguminosarum requires an ABC transporter and affects competition for nodulation Presentation Time: 0930 - 1000 Plasmid curing has shown that the ability to use glycerol as a carbon source is plasmid-encoded in Rhizobium leguminosarum (Baldani et al. 1992, Yost et al. 2006). We isolated the locus responsible for glycerol utilization from plasmid pRleVF39c in R. leguminosarum bv. viciae VF39. This region was analyzed by DNA sequencing and mutagenesis. The locus encompasses a gene encoding GlpR (a DeoR regulator), genes encoding an ABC transporter, and genes glpK and glpD, encoding a kinase and dehydrogenase. All the genes except the regulatory gene glpR were organized into a single operon, and were required for growth on glycerol. The glp operon was strongly induced by both glycerol and glycerol-3-phosphate, as well as by pea seed exudate. GlpR repressed the operon in the absence of inducer. Mutation of genes coding for the ABC transporter abolished all transport of glycerol in transport assays using radiolabelled glycerol. This confirms that, unlike in other organisms like Escherichia coli and Pseudomonas aeruginosa, which use facilitated diffusion, glycerol uptake occurs by an active process in R. leguminosarum. Since the glp locus is highly conserved in all sequenced R. leguminosarum and R. etli strains, as well as in Sinorhizobium spp. and Agrobacterium spp. and other alphaproteobacteria, this process for glycerol uptake is probably widespread. Mutants unable to use glycerol were deficient in competitiveness for nodulation of peas compared to wild-type, indicating that glycerol catabolism confers an advantage to the bacterium in the rhizosphere or in the infection thread. Baldani JI, Weaver R, Hynes MF, & Eardly B (1992) Utilization of carbon substrates, electrophoretic enzyme patterns, and symbiotic performance of clover rhizobia cured of plasmids. Appl Environ Microbiol 58:2308-2314 Yost CK, Rath AM, Noel TC, & Hynes MF (2006) Characterization of genes involved in erythritol catabolism in Rhizobium leguminosarum bv. viciae. . Microbiology 152:2061-2074 35 2011

17 th <strong>International</strong> Congress on <strong>Nitrogen</strong> <strong>Fixation</strong><br />

Fremantle, Western Australia<br />

27 November – 1 December 2011<br />

Session Details: Tuesday 29 November 2011<br />

Plenary Session 3<br />

0900 - 1030<br />

Authors: Wayne G. Reeve 1 and Nikos Kyrpidis 2<br />

1 Centre for Rhizobium Studies, School of Biological Sciences and Biotechnology,<br />

Murdoch University, South Street, Murdoch 6150, Australia.<br />

2 DOE Joint Genome Institute
, Walnut Creek, CA, USA<br />

Presentation Title: The GEBA - Root Nodule Bacteria Community Sequencing Project<br />

Presentation Time: 0900 - 0930<br />

Genome sequencing has revolutionized understanding of microorganisms and the roles they play in important<br />

processes such as pathogenesis, energy production, bioremediation, global nutrient cycles, and the origins,<br />

evolution, and diversity of life. However, there are significant gaps in microbial genome sequence availability<br />

especially associated with environmental genomics. The currently available microbe genome sequences show a<br />

highly biased phylogenetic distribution compared to the extent of microbial diversity known today. This bias has<br />

resulted in a major gap in our knowledge of microbial genome complexity and our understanding of the evolution,<br />

physiology, and metabolic capacity of microbes. There is a strong need for a large-scale systematic effort to<br />

sequence genomes to fill in genomic gaps in the tree of life. To this end the Genomic Encyclopedia of Bacteria<br />

and Archaea – Root Nodule Bacteria (GEBA-RNB) initiative at the Joint Genome Institute aims to sequence 100<br />

RNB strains of commercial, genetic and ecological importance. This project will support the systematic<br />

sequence-based studies and understanding of the biogeographical effects on species evolution as well as the<br />

mechanisms of symbiotic nitrogen fixation by RNB. Shared genetic mechanisms between fungal and bacterial<br />

root endosymbioses exist and a detailed understanding of endosymbionts will be beneficial to drive bioenergy<br />

development from trees. The GEBA-RNB project is based on collaboration between JGI and an international<br />

consortium from 15 countries coordinated by the Centre for Rhizobium Studies at Murdoch University.<br />

34<br />

2011

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