Genome reduction boosts heterologous gene expression in XXXX .

@entity855 @entity26731 @entity15250 @entity1319
BACKGROUND: The implementation of novel platform organisms to be used as microbial cell factories in industrial applications is currently the subject of intense research. Ongoing efforts include the adoption of @entity26731 variants with a reduced genome as the functional chassis for biotechnological purposes. In these strains, dispensable functions removed @entity1319 (1.1% of the genome) and a number of open reading frames expected to improve genotypic and phenotypic stability of the cells upon deletion (3.2% of the genome). RESULTS: In this study, two previously constructed multiple-deletion @entity15250 strains were systematically evaluated as microbial cell factories for heterologous protein production and compared to the parental bacterium (strain @entity26731 ) with regards to several industrially-relevant physiological traits. Energetic parameters were quantified at different controlled growth rates in continuous cultivations and both strains had a higher @entity855 content, increased adenylate energy charges, and diminished maintenance demands than the wild-type strain. Under all the conditions tested the mutants also grew faster, had enhanced biomass yields and showed higher viability, and displayed increased plasmid stability than the parental strain. In addition to small-scale shaken-flask cultivations, the performance of the genome-streamlined strains was evaluated in larger scale bioreactor batch cultivations taking a step towards industrial growth conditions. When the production of the green fluorescent protein (used as a model heterologous protein) was assessed in these cultures, the mutants reached a recombinant protein yield with respect to biomass up to 40% higher than that of @entity26731 . CONCLUSIONS: The two streamlined-genome derivatives of @entity26731 outcompeted the parental strain in every industrially-relevant trait assessed, particularly under the working conditions of a bioreactor. Our results demonstrate that these genome-streamlined bacteria are not only robust microbial cell factories on their own, but also a promising foundation for further biotechnological applications.
