Catabolic pathway acquisition by rhizosphere bacteria readily enables growth with a root exudate component but does not affect root colonization.

Horizontal gene transfer (HGT) is a fundamental evolutionary process that plays a key role in bacterial evolution. The likelihood of a successful transfer event is expected to depend on the precise balance of costs and benefits resulting from pathway acquisition. Most experimental analyses of HGT have focused on phenotypes that have large fitness benefits under appropriate selective conditions, such as antibiotic resistance.

Evaluation of chromosomal insertion loci in the Pseudomonas putida KT2440 genome for predictable biosystems design.

The development of strains for industrial production of fuels and chemicals will require the integration of heterologous genes and pathways into the chromosome. Finding the most appropriate integration site to maximize strain performance is an essential part of the strain design process. We characterized seven chromosomal loci in KT2440 for integration of a fluorescent protein expression construct.

Biotechnology of cyanobacterial isoprene production.

Heterologous cyanobacterial production of isoprene (CH) presents an opportunity to develop renewable resources for fuel and industrial chemicals. Isoprene can be generated photosynthetically in these microorganisms from dimethylallyl-diphosphate (DMAPP) by the recombinant enzyme isoprene synthase (ISPS), as a transgenic product of the isoprenoid biosynthetic pathway. The present work sought to combine recent enhancements in the cellular level of reactant (DMAPP) and enzyme (ISPS), as a means in the further development of this technology.

Engineering isoprene synthesis in cyanobacteria.

The renewable production of isoprene (Isp) hydrocarbons, to serve as fuel and synthetic chemistry feedstock, has attracted interest in the field recently. Isp (C H ) is naturally produced from sunlight, CO and H O photosynthetically in terrestrial plant chloroplasts via the terpenoid biosynthetic pathway and emitted in the atmosphere as a response to heat stress. Efforts to institute a high capacity continuous and renewable process have included heterologous expression of the Isp synthesis pathway in photosynthetic microorganisms.

Engineering Isoprene Synthase Expression and Activity in Cyanobacteria.

Efforts to heterologously produce quantities of isoprene hydrocarbons (CH) renewably from CO and HO through the photosynthesis of cyanobacteria face barriers, including low levels of recombinant enzyme accumulation compounded by their slow innate catalytic activity. The present work sought to alleviate the "expression level" barrier upon placing the isoprene synthase (IspS) enzyme in different fusion configurations with the cpcB protein, the highly expressed β-subunit of phycocyanin. Different cpcB*IspS fusion constructs were made, distinguished by the absence or presence of linker amino acids between the two proteins.

Role of isopentenyl-diphosphate isomerase in heterologous cyanobacterial (Synechocystis) isoprene production.

Heterologous production of isoprene (CH) hydrocarbons in cyanobacteria, emanating from sunlight, CO, and water, is now attracting increasing attention. The concept entails application of an isoprene synthase transgene from terrestrial plants, heterologously expressed in cyanobacteria, aiming to reprogram carbon flux in the terpenoid biosynthetic pathway toward formation and spontaneous release of this volatile chemical from the cell and liquid culture. However, flux manipulations and carbon-partitioning reactions between isoprene (the product) and native terpenoid biosynthesis for cellular needs are not yet optimized for isoprene yield.