Engineering Escherichia coli to produce aromatic chemicals from ethylene glycol.

Microbial overproduction of aromatic chemicals has gained considerable industrial interest and various metabolic engineering approaches have been employed in recent years to address the associated challenges. So far, most studies have used sugars (mostly glucose) or glycerol as the primary carbon source. In this study, we used ethylene glycol (EG) as the main carbon substrate. EG could be obtained from the degradation of plastic and cellulosic wastes. As a proof of concept, Escherichia coli was engineered to transform EG into L-tyrosine, a valuable aromatic amino acid. Under the best fermentation condition, the strain produced 2 g/L L-tyrosine from 10 g/L EG, outperforming glucose (the most common sugar feedstock) in the same experimental conditions. To prove the concept that EG can be converted into different aromatic chemicals, E. coli was further engineered with a similar approach to synthesize other valuable aromatic chemicals, L-phenylalanine and p-coumaric acid. Finally, waste polyethylene terephthalate (PET) bottles were degraded using acid hydrolysis and the resulting monomer EG was transformed into L-tyrosine using the engineered E. coli, yielding a comparable titer to that obtained using commercial EG. The strains developed in this study should be valuable to the community for producing valuable aromatics from EG.

Producing aromatic amino acid from corn husk by using polyols as intermediates.

Agricultural biomass remains as one of the commonly found waste on Earth. Although valorisation of these wastes has been studied in detail, the fermentation-based processes still need improvement due to the high cost of hydrolysing enzymes, and the presence of growth inhibitors which constrains the fermentation to produce high-value products. To address these challenges, we developed an integrated process in this study combining abiotic- and bio-catalysis to produce l-tyrosine from corn husk. The first step involved a one-pot hydrolytic hydrogenation tandem reaction without the use of the expensive enzymes, which yielded a mixture of polyols and sugars. Without any purification, these crude hydrolysates can be almost completely utilized by an engineered Escherichia coli strain, which did not exhibit any growth inhibition. The strain produced 0.44 g/L l-tyrosine from 10 g/L crude corn husk hydrolysates, demonstrating the feasibility of converting agricultural biomass into a valuable aromatic amino acid via an integrated process.

C2 feedstock-based biomanufacturing of value-added chemicals.

Engineering microbes to produce value-added chemicals from C6/C5 sugars sometimes requires long biosynthetic pathways, which causes carbon loss due to involving multiple metabolic branch nodes, leading to a lower product yield. Using C2 feedstocks derived from gaseous, cellulosic, and plastic wastes could establish shorter biosynthetic pathways to produce some target chemicals, for example, acetyl-CoA-derived natural products. Utilizing these waste-derived feedstocks would also contribute to reducing the carbon footprint of the chemical industry. In this review, we highlighted the promising waste-processing technologies that could provide C2 feedstocks that are compatible with microbial fermentation. We also analyzed the recent metabolic engineering works in which the microorganisms/fermentation processes were modified/optimized to utilize acetate, ethanol, or ethylene glycol more efficiently.

Development of a novel 7 immune-related genes prognostic model for oral cancer: A study based on TCGA database.

Oral squamous cell carcinoma (OSCC) is an aggressive tumor whose prognosis has little improvement in the last three decades. Various immune-related genes have been suggested as significant roles in the development and progression of malignant cancers. In this study, we acquired and integrated differentially expressed genes of OSCC patients, including immune-related genes and transcription factors (TFs), from The Cancer Genome Atlas (TCGA) database. TF-mediated network was established to exploring the regulatory mechanisms of prognostic immune-related genes. A 7 immune-related genes prognostic model for OSCC was obtained, including CGB8, CTLA4, TNFRSF19, CCL26, NRG1, TPM2 and PLAU, which was further proved to be an independent prognostic indicator after adjusting for other clinical factors. The immune-related genes prognostic index was significantly negatively correlated to the infiltration abundances of B cells (P < 0.05) and CD8+ T cells (P < 0.05). The novel proposed immune-based prognostic model not only provided a promising biomarker and a way to monitor the long-term treatment of OSCC, but also gave a new insight into a potential immunotherapy strategy.

Galactose 1-phosphate accumulates to high levels in galactose-treated cells due to low GALT activity and absence of product inhibition of GALK.

Classic Galactosaemia is a genetic disorder, characterised by galactose intolerance in newborns. It occurs due to recessive mutations in the galactose-1-phosphate uridylyltransferase (GALT) gene. One of the main alterations caused by GALT deficiency is the accumulation of galactose 1-phosphate (Gal-1P) in cells. Studies have suggested that Gal-1P exerts cellular toxicity, possibly by inhibiting cellular metabolism. However, the exact significance of Gal-1P in disease pathogenesis remains unclear. In this study, we tested the hypothesis that Gal-1P inhibits cellular glucose utilisation by competing with substrates in the glycolytic pathway. We also investigated the metabolism of both galactose and glucose in GALT-expressing HEK293T and 143B cells to identify critical reactions steps contributing to the metabolic toxicity of galactose. Notably, we found that galactose-treated HEK293T and 143B cells, which express endogenous GALT, accumulate markedly high intracellular Gal-1P concentrations. Despite very high intracellular Gal-1P concentrations, no inhibition of cellular glucose uptake and no significant changes in the intracellular concentrations of glycolytic metabolites were observed. This indicates that Gal-1P does not exert an inhibitory effect on glycolysis in cells and rules out one potential hypothesis for cellular Gal-1P toxicity. We also investigated the mechanism responsible for the observed Gal-1P accumulation. Our results suggest that Gal-1P accumulation is a result of both low GALT activity and the absence of product inhibition by Gal-1P on galactokinase (GALK1), the enzyme responsible for phosphorylating galactose to Gal-1P. These findings provide a better understanding of the disease mechanisms underlying Classic Galactoaemia.