Enabling anoxic acetate assimilation by electrode-driven respiration in the obligate aerobe, Pseudomonas putida.

This study examined the obligate aerobe, Pseudomonas putida, using acetate as the sole carbon and energy source, and respiration via an anode as the terminal electron acceptor under anoxic conditions. P. putida showed significantly different acetate assimilation in a closed-circuit microbial fuel cell (CC-MFC) compared to an open circuit MFC (OC-MFC).

Supply of proton enhances CO electrosynthesis for acetate and volatile fatty acid productions.

The microbial electrosynthesis is a platform to supply protons and electrons to improve the conversion efficiency and production rate for the valorization of C1 gas. This study examined proton migration and electron transfer of the electrode and microbe by using various external parameters in the electrosynthesis of CO. The CO electrosynthesis achieved almost double of coulombic efficiency than the conventional CO electrosynthesis.

Development of Klebsiella pneumoniae J2B as microbial cell factory for the production of 1,3-propanediol from glucose.

1,3-Propanediol (1,3-PDO) is an important platform chemical which has a wide application in food, cosmetics, pharmaceutical and textile industries. Its biological production using recombinant Escherichia coli with glucose as carbon source has been commercialized by DuPont, but E. coli cannot synthesize coenzyme B which is an essential and expensive cofactor of glycerol dehydratase, a core enzyme in 1,3-PDO biosynthesis.

Development of 3-hydroxypropionic-acid-tolerant strain of Escherichia coli W and role of minor global regulator yieP.

3-Hydroxypropionic acid (3-HP) is an important platform chemical, but its toxic effect at high concentrations (> 200 mM) is a serious challenge for commercial production. In this study, a highly 3-HP-tolerant strain of Escherichia coli W (tolerance concentration: 400 mM in M9 minimal medium and 800 mM when yeast extract was added) was developed by adaptive laboratory evolution (ALE) with glycerol as the carbon source. Genome analysis of the adapted strain (designated as E.

Metabolic engineering of Klebsiella pneumoniae J2B for co-production of 3-hydroxypropionic acid and 1,3-propanediol from glycerol: Reduction of acetate and other by-products.

Production of 3-hydroxypropionic acid (3-HP) or 1,3-propanediol (1,3-PDO) production from glycerol is challenging due to the problems associated with cofactor regeneration, coenzyme B synthesis, and the instability of pathway enzymes. To address these complications, simultaneous production of 3-HP and 1,3-PDO, instead of individual production of each compound, was attempted. With over-expression of an aldehyde dehydrogenase, recombinant Klebsiella pneumoniae could co-produce 3-HP and 1,3-PDO successfully.

Production of 3-hydroxypropionic acid by balancing the pathway enzymes using synthetic cassette architecture.

Biological 3-hydroxypropionic acid (3-HP) production from glycerol is a two-step reaction catalyzed by glycerol dehydratase (GDHt) and aldehyde dehydrogenase (ALDH). Recombinant strains developed for 3-HP production often suffer from the accumulation of a toxic intermediate, 3-hydroxypropionaldehyde (3-HPA). In order to avoid 3-HPA accumulation, balancing of the two enzymatic activities, in the present study, was attempted by employment of synthetic-regulatory cassettes comprising varying-strength promoters and bicistronic ribosome-binding sites (RBSs).

Metabolic engineering of Klebsiella pneumoniae J2B for the production of 1,3-propanediol from glucose.

The production of 1,3-propanediol (1,3-PDO) from glucose was investigated using Klebsiella pneumoniae J2B, which converts glycerol to 1,3-PDO and synthesize an essential coenzyme B. In order to connect the glycolytic pathway with the pathway of 1,3-PDO synthesis from glycerol, i.e.

Co-production of hydrogen and ethanol from glucose in by activation of pentose-phosphate pathway through deletion of phosphoglucose isomerase () and overexpression of glucose-6-phosphate dehydrogenase () and 6-phosphogluconate dehydrogenase ().

Background: Biologically, hydrogen (H) can be produced through dark fermentation and photofermentation. Dark fermentation is fast in rate and simple in reactor design, but H production yield is unsatisfactorily low as <4 mol H/mol glucose. To address this challenge, simultaneous production of H and ethanol has been suggested.

Y19 for constitutive expression of carbon monoxide-dependent hydrogen-production machinery.

Background: Y19 is a good biocatalyst for production of hydrogen (H) from oxidation of carbon monoxide (CO) via the so-called water-gas-shift reaction (WGSR). It has a high H-production activity (23.83 mmol H g cell h) from CO, and can grow well to a high density on various sugars.

Measurement of crude-cell-extract glycerol dehydratase activity in recombinant Escherichia coli using coupled-enzyme reactions.

Glycerol dehydratase (GDHt), which converts glycerol to 3-hydroxypropionaldehyde, is essential to the production of 1,3-propanediol (1,3-PDO) or 3-hydroxypropionic acid (3-HP). A reliable GDHt activity assay in crude-cell extract was developed. In the assay, GDHt converted 1,2-propanediol (1,2-PDO) to propionaldehyde, which was further converted to 1-propionic acid by aldehyde dehydrogenase (KGSADH) or to 1-propanol by yeast-alcohol dehydrogenase (yADH), while the NADH concentration change was monitored spectrophotometrically.

Co-production of hydrogen and ethanol by pfkA-deficient Escherichia coli with activated pentose-phosphate pathway: reduction of pyruvate accumulation.

Background: Fermentative hydrogen (H2) production suffers from low carbon-to-H2 yield, to which problem, co-production of ethanol and H2 has been proposed as a solution. For improved co-production of H2 and ethanol, we developed Escherichia coli BW25113 ΔhycA ΔhyaAB ΔhybBC ΔldhA ΔfrdAB Δpta-ackA ΔpfkA (SH8*) and overexpressed Zwf and Gnd, the key enzymes in the pentose-phosphate (PP) pathway (SH8*_ZG). However, the amount of accumulated pyruvate, which was significant (typically 0.

Co-production of hydrogen and ethanol from glucose by modification of glycolytic pathways in Escherichia coli - from Embden-Meyerhof-Parnas pathway to pentose phosphate pathway.

Hydrogen (H2) production from glucose by dark fermentation suffers from the low yield. As a solution to this problem, co-production of H2 and ethanol, both of which are good biofuels, has been suggested. To this end, using Escherichia coli, activation of pentose phosphate (PP) pathway, which can generate more NADPH than the Embden-Meyhof-Parnas (EMP) pathway, was attempted.

Inducible gene expression system by 3-hydroxypropionic acid.

Background: 3-Hydroxypropionic acid (3-HP) is an important platform chemical that boasts a variety of industrial applications. Gene expression systems inducible by 3-HP, if available, are of great utility for optimization of the pathways of 3-HP production and excretion.

Results: Here we report the presence of unique inducible gene expression systems in Pseudomonas denitrificans and other microorganisms.

Complete genome sequence of novel carbon monoxide oxidizing bacteria Citrobacter amalonaticus Y19, assembled de novo.

We report here the complete genome sequence of Citrobacter amalonaticus Y19 isolated from an anaerobic digester. PacBio single-molecule real-time (SMRT) sequencing was employed, resulting in a single scaffold of 5.58Mb.

Carbon and energy balances of glucose fermentation with hydrogenproducing bacterium Citrobacter amalonaticus Y19.

For the newly isolated H2-producing chemoheterotrophic bacterium Citrobacter amalonaticus Y19, anaerobic glucose metabolism was studied in batch cultivation at varying initial glucose concentrations (3.5- 9.5 g/l).