Project description:The genome of Cupriavidus necator H16 encodes multiple homologous enzymes predicted to be involved in itaconic acid metabolism. Here, we performed RNA-seq analysis to identify genes and gene clusters that are differentially expressed in response to itaconic acid, as well as the metabolically related compounds methylsuccinic acid and mesaconic acid.
Project description:These data belong to a metabolic engineering project that introduces the reductive glycine pathway for formate assimilation in Cupriavidus necator. As part of this project we performed short-term evolution of the bacterium Cupriavidus necator H16 to grow on glycine as sole carbon and energy source. Some mutations in a putiative glycine transporting systems facilitated growth, and we performed transcriptomics on the evolved strain growing on glycine. Analysis of these transcriptomic data lead us to the discovery of a glycine oxidase (DadA6), which we experimentally demonstrated to play a key role in the glycine assimilation pathay in C. necator.
Project description:Uptake and fixation of CO2 are central to strategies for CO2-based biomanufacturing. Cupriavidus necator H16 has emerged as a promising industrial host for this purpose. Despite its prominence, the ability to engineer C. necator inorganic carbon uptake and fixation is underexplored. Here, we test the role of endogenous and heterologous genes on C. necator inorganic carbon metabolism. Deletion of one of the four carbonic anhydrases in C. necator, β-carbonic anhydrase can, had the most deleterious effect on C. necator autotrophic growth. Replacement of this native uptake system with several classes of dissolved inorganic carbon (DIC) transporters from Cyanobacteria and chemolithoautotrophic bacteria recovered autotrophic growth and supported higher cell densities compared to wild-type (WT) C. necator in saturating CO2 in batch culture. Several heterologous strains with Halothiobacillus neopolitanus DAB2 (hnDAB2) expressed from the chromosome in combination with diverse rubisco homologs grew in CO2 equally or better than the wild-type strain. Our experiments suggest that the primary role of Can carbonic anhydrase during autotrophic growth is for bicarbonate accumulation to support anaplerotic metabolism, and an array of DIC transporters can complement this function. This work demonstrates flexibility in HCO3- uptake and CO2 fixation in C. necator, providing new pathways for CO2-based biomanufacturing.
Project description:Abstract. Microbial gas fermentation remains a promising biotechnology for the production of a variety of industrially relevant chemicals under relatively benign conditions using ubiquitous feedstocks, such as carbon dioxide. Implementation of these gas fermentation processes requires an understanding of the microbial response to different ratios of the gaseous feedstocks (carbon dioxide, oxygen, and hydrogen) supplied to the reactor. Here, we used Cupriavidus necator (strain ATCC 17699 / DSM 428 / KCTC 22496 / NCIMB 10442 / H16 / Stanier 337) as a microbial biocatalyst due to its metabolic diversity, genetic tractability, and ability to grow to high cell densities during aerobic fermentation in bioreactors. Specifically, we investigate whether the supply of different proportions of hydrogen and carbon dioxide in the gas stream (1:1, 3:1, and 8:1 H2:CO2) affects the physiology of C. necator, with a focus on the accumulation of single cell protein (SCP) and poly-3-hydroxybutyrate (PHB) within the microbial biomass. We found that an 8:1 ratio of H2:CO2 led to both the highest overall biomass production and PHB content within the biomass after a seven-day incubation. Intracellular SCP content varied as a function of both length of incubation and gas ratio supplied. We conducted a proteomic analysis to determine whether differences in productivity could be correlated with changes in protein expression over time and across treatment groups. This study highlights the importance of considering gaseous substrate composition and its potential effects on microbial physiology and metabolism during fermentation.