Why Sequence Variovorax paradoxus?

DOE-JGI will be sequencing two strains of the β-proteobacterium Variovorax paradoxus, which are distinct and especially relevant to DOE. Variovorax species are catabolically very diverse and engage in mutually beneficial interactions with other bacterial species in many biodegradations. For example, a soil methanotroph, only when co-cultured together with a V. paradoxus strain, exhibits high affinity for methane (a potent greenhouse gas), and this trait is not usually observed in laboratory cultures. Similarly, a close relative of Variovorax has been found to be the central, nonphotosynthetic partner within the phototrophic consortium "Chlorochromatium aggregatum.” Since these two groups are already being sequenced at JGI, the V. paradoxus genome sequence will likely have additional value in those efforts.

Variovorax also has the ability to interfere with the communication of other bacteria. Moreover, Variovorax can intimately interact with other biota (e.g., plants) in various ecosystems. It also appears well poised in its metabolic potential to compete for gases and organics typically produced and released into the environment by other biota. Moreover, Variovorax, residing in the area just outside plant roots and/or inside a plant, can promote plant growth via the reduction of ethylene levels, the repression of quorum-sensing-controlled pathogenesis, and the increase of resistance to heavy metals, which greatly benefits phytoremediation. Thus, V. paradoxus is an excellent choice for continued studies on novel biodegradation, as well as microbe/microbe and microbe/plant interactions.

In spite of its ecological importance and high application potential, however, none of the species belonging to the genus has been sequenced. Sequence information from this project will allow researchers to discover the ecological roles of Variovorax in biota involved in diverse types of biodegradation. It will also contribute to our understanding of the evolution and ecology of catabolic pathways for compounds including explosives, energetic materials, and pesticides, such as those found as contaminants at DOE and DoD sites.

Principal Investigators: Jong-In Han (Rensselaer Polytechnic Inst.), Paul Orwin (California State Univ.), Jim C. Spain (Georgia Inst. of Technology), and Jared R. Leadbetter (California Inst. of Technology)