[Metabolic engineering of for thymidine production].

Thymidine, as a crucial precursor of anti-AIDS drugs (e.g., zidovudine and stavudine), has wide application potential in the pharmaceutical industry.

Co-utilization of carbon sources in microorganisms for the bioproduction of chemicals.

Carbon source is crucial for the cell growth and metabolism in microorganisms, and its utilization significantly affects the synthesis efficiency of target products in microbial cell factories. Compared with a single carbon source, co-utilizing carbon sources provide an alternative approach to optimize the utilization of different carbon sources for efficient biosynthesis of many chemicals with higher titer/yield/productivity. However, the efficiency of bioproduction is significantly limited by the sequential utilization of a preferred carbon source and secondary carbon sources, attributed to carbon catabolite repression (CCR).

Phenotype-genotype mapping reveals the betaine-triggered L-arginine overproduction mechanism in Escherichia coli.

The production phenotype improvement of industrial microbes is extremely needed and challenging. Environmental factors optimization provides insightful ideas to trigger the superior production phenotype by activating potential genetic determiners. Here, phenotype-genotype mapping was used to dissect the betaine-triggered L-arginine overproduction mechanism and mine beneficial genes for further improving production phenotype.

Metabolic reprogramming and biosensor-assisted mutagenesis screening for high-level production of L-arginine in Escherichia coli.

L-arginine is a value-added amino acid with promising applications in the pharmaceutical and nutraceutical industries. Further unleashing the potential of microbial cell factories to make L-arginine production more competitive remains challenging due to the sophisticated intracellular interaction networks and the insufficient knowledge of global metabolic regulation. Here, we combined multilevel rational metabolic engineering with biosensor-assisted mutagenesis screening to exploit the L-arginine production potential of Escherichia coli.

Reconstructing a recycling and nonauxotroph biosynthetic pathway in Escherichia coli toward highly efficient production of L-citrulline.

L-citrulline is a high-value amino acid with promising application in medicinal and food industries. Construction of highly efficient microbial cell factories for L-citrulline production is still an open issue due to complex metabolic flux distribution and L-arginine auxotrophy. In this study, we constructed a nonauxotrophic cell factory in Escherichia coli for high-titer L-citrulline production by coupling modular engineering strategies with dynamic pathway regulation.

Metabolic engineering of Escherichia coli for efficient osmotic stress-free production of compatible solute hydroxyectoine.

Compatible solutes are key for the ability of halophilic bacteria to resist high osmotic stress. They have received wide attention from researchers for their excellent osmotic protection properties. Hydroxyectoine is a particularly important compatible solute, but its production by microbes faces several challenges, including low titer/yield, the presence of the byproduct ectoine, and the requirement of high salinity.

Flux redistribution of central carbon metabolism for efficient production of l-tryptophan in Escherichia coli.

Microbial production of l-tryptophan (l-trp) has received considerable attention because of its diverse applications in food additives and pharmaceuticals. Overexpression of rate-limiting enzymes and blockage of competing pathways can effectively promote microbial production of l-trp. However, the biosynthetic process remains suboptimal due to imbalanced flux distribution between central carbon and tryptophan metabolism, presenting a major challenge to further improvement of l-trp yield.

Identification and biochemical characterisation of a novel methionine aminopeptidase from the taiga tick Ixodes persulcatus.

Methionine aminopeptidases (MetAPs), which remove the initiator methionine from nascent peptides, are essential in all organisms and considered to be a valuable targets for the treatment of various diseases, including cancer, malaria, and bacterial infections. However, MetAPs have not been reported in hard ticks (family Ixodidae), and their bioinformatics characterisation in tick's genome sequences is limited. In this study, we cloned, identified, and characterised a novel MetAP from Ixodes persulcatus, a vector for pathogens causing Lyme borreliosis and tick-borne encephalitis.

High-yield production of L-valine in engineered Escherichia coli by a novel two-stage fermentation.

L-valine is an essential amino acid and an important amino acid in the food and feed industry. The relatively low titer and low fermentation yield currently limit the large-scale application of L-valine. Here, we constructed a chromosomally engineered Escherichia coli to efficiently produce L-valine.

Highly Efficient Production of l-Histidine from Glucose by Metabolically Engineered .

l-Histidine is a functional amino acid with numerous therapeutic and ergogenic properties. It is one of the few amino acids that is not produced on a large scale by microbial fermentation due to the lack of an efficient microbial cell factory. In this study, we demonstrated the engineering of wild-type to overproduce histidine from glucose.

Multiple-step chromosomal integration of divided segments from a large DNA fragment via CRISPR/Cas9 in Escherichia coli.

Although CRISPR/Cas9-mediated gene editing technology has developed vastly in Escherichia coli, the chromosomal integration of large DNA fragment is still challenging compared with gene deletion and small fragment integration. Moreover, to guarantee sufficient Cas9-induced double-strand breaks, it is usually necessary to design several gRNAs to select the appropriate one. Accordingly, we established a practical daily routine in the laboratory work, involving multiple-step chromosomal integration of the divided segments from a large DNA fragment.

Metabolic engineering of Escherichia coli for high-yield uridine production.

Uridine is a kind of pyrimidine nucleoside that has been widely applied in the pharmaceutical industry. Although microbial fermentation is a promising method for industrial production of uridine, an efficient microbial cell factory is still lacking. In this study, we constructed a metabolically engineered Escherichia coli capable of high-yield uridine production.

Metabolic engineering of Bacillus subtilis for the co-production of uridine and acetoin.

In this study, a uridine and acetoin co-production pathway was designed and engineered in Bacillus subtilis for the first time. A positive correlation between acetoin and uridine production was observed and investigated. By disrupting acetoin reductase/2,3-butanediol dehydrogenasegenebdhA, the acetoin and uridine yield was increased while 2,3-butanediol formation was markedly reduced.

Improvement of uridine production of Bacillus subtilis by atmospheric and room temperature plasma mutagenesis and high-throughput screening.

In the present study, a novel breeding strategy of atmospheric and room temperature plasma (ARTP) mutagenesis was used to improve the uridine production of engineered Bacillus subtilis TD12np. A high-throughput screening method was established using both resistant plates and 96-well microplates to select the ideal mutants with diverse phenotypes. Mutant F126 accumulated 5.

Synthesis and magnetic properties of manganite multiple heterostructure nanoribbons.

The fabrication and applications of two-dimensional complex oxide heterostructures have gained great attention. However, the achievement of these materials in one-dimensional form with multiple interfaces is still elusive. Here, we report the growth of manganite CaMn(3)O(6)/CaMn(2)O(4) heterostructure nanoribbons via the use of CaMnO(3) powders as the precursor for the molten-salt process.

Automated method for optimization of electric field distributions and optical parameters in thin-film polarizers.

An efficient method based on the modified needle optimization technique is proposed to design high-power laser thin-film polarizers. In order to minimize the influence of the standing-wave electric field on the laser-induced damage threshold of the polarizers, a crucial optimization parameter, the maximum electric field intensity in the high-refractive-index layers, is included in the proposed merit function. The electric field distribution and optical performance obtained by the proposed method are studied.