Efficient L-valine production using systematically metabolic engineered Klebsiella oxytoca.

L-Valine, a branched-chain amino acid with diversified applications, is biosynthesized with α-acetolactate as the key precursor. In this study, the metabolic flux in Klebsiella oxytoca PDL-K5, a Risk Group 1 organism producing 2,3-butanediol as the major fermentation product, was rearranged to L-valine production by introducing exogenous L-valine biosynthesis pathway and blocking endogenous 2,3-butanediol generation at the metabolic branch point α-acetolactate. After further enhancing L-valine efflux, strengthening pyruvate polymerization and selecting of key enzymes for L-valine synthesis, a plasmid-free K.

[Responses of soil microbial community structure to litter inputs.].

Litter decomposition is one of the most important ecosystem processes, which plays a critical role in regu-lating nutrient cycling and energy flow in terrestrial ecosystems. The influence of litter inputs on soil microbial community is helpful for understanding the relationship between soil microbial diversity and terrestrial ecosystem function. We conducted a meta-analysis to examine how litter inputs affect soil microbial activity (fungi, bacteria, actinomycetes) and microbial biomass carbon, nitrogen in China.

2,3-Butanediol synthesis from glucose supplies NADH for elimination of toxic acetate produced during overflow metabolism.

Overflow metabolism-caused acetate accumulation is a major problem that restricts industrial applications of various bacteria. 2,3-Butanediol (2,3-BD) synthesis in microorganisms is an ancient metabolic process with unidentified functions. We demonstrate here that acetate increases and then decreases during the growth of a bacterium Enterobacter cloacae subsp.

Pyruvate Production from Whey Powder by Metabolic Engineered .

Pyruvate is an important platform material widely used in food, pharmaceutical, and chemical industries. Pyruvatetolerant PDL-0 was chosen as a chassis for pyruvate production via metabolic engineering. Genes related to by-product generation were knocked out to decrease the production of 2,3-butantediol, acetate, ethanol, and succinate.

Efficient 2,3-butanediol production from whey powder using metabolically engineered Klebsiella oxytoca.

Background: Whey is a major pollutant generated by the dairy industry. To decrease environmental pollution caused by the industrial release of whey, new prospects for its utilization need to be urgently explored. Here, we investigated the possibility of using whey powder to produce 2,3-butanediol (BDO), an important platform chemical.

Comparison of transcatheter arterial chemoembolization combined with radiofrequency ablation or microwave ablation for the treatment of unresectable hepatocellular carcinoma: a systemic review and meta-analysis.

Transcatheter arterial chemoembolization (TACE), radiofrequency ablation (RFA), and microwave ablation (MWA) are regarded as effective therapies for treating unresectable hepatocellular carcinoma (HCC). We conducted this study to compare the efficiency and safety of TACE combined with RFA (TR group) or MWA (TM group). PubMed, the Cochrane Library, Ovid Medline, Web of Science, Scopus, Embase, ScienceDirect, and Google Scholar were searched.

Metabolic Engineering of for Production of Acetoin.

Acetoin is a potential platform compound for a variety of chemicals. MW3, a thermophilic and generally regarded as safe (GRAS) microorganism, can produce 2,3-butanediol with a high concentration, yield, and productivity. In this study, MW3 was metabolic engineered for acetoin production.

Engineering of glycerol utilization in Gluconobacter oxydans 621H for biocatalyst preparation in a low-cost way.

Background: Whole cells of Gluconobacter oxydans are widely used in various biocatalytic processes. Sorbitol at high concentrations is commonly used in complex media to prepare biocatalysts. Exploiting an alternative process for preparation of biocatalysts with low cost substrates is of importance for industrial applications.

d-2-Hydroxyglutarate dehydrogenase plays a dual role in l-serine biosynthesis and d-malate utilization in the bacterium .

is a very large bacterial genus in which several species can use d-malate for growth. However, the enzymes that can metabolize d-malate, such as d-malate dehydrogenase, appear to be absent in most species. d-3-Phosphoglycerate dehydrogenase (SerA) can catalyze the production of d-2-hydroxyglutarate (d-2-HG) from 2-ketoglutarate to support d-3-phosphoglycerate dehydrogenation, which is the initial reaction in bacterial l-serine biosynthesis.