Strong promoters might not be optimal to obtain maximum metabolic flux towards desired products, whereas modulating gene expression with multiple regulatory parts is an option to obtain optimal expression strength. Therefore, we assessed the difference of impact on beta-carotene production between modulating isoprenoid gene expression with multiple regulatory parts and strong promoter, to improve beta-carotene production through combined modulation of essential isoprenoid genes. Eight isoprenoid genes were modulated with six artificial regulatory parts having a wide range of strengths to assess their effects on beta-carotene production. Optimal strength for each isoprenoid gene expression was identified, leading to 1.2 to 3.5-fold increase in beta-carotene production. In contrast to previous reports, our work suggests that modulating dxr, ispG and ispH genes with appropriate strengths increase beta-carotene production. Beta-carotene yield reached 17.59 mg/g after combined modulation of dxs and idi genes, 8-fold higher than that of the parent strain. Modulating gene expression with multiple regulatory parts was better than strong promoter, providing a new gene modulation strategy for targeted biosynthesis.
Escherichia coli ; genetics ; metabolism ; Gene Expression Regulation ; Promoter Regions, Genetic ; Terpenes ; metabolism ; beta Carotene ; biosynthesis

As an important model industrial microorganism, Escherichia coli has been widely used in pharmaceutical, chemical industry and agriculture. In the past 30 years, a variety of new strategies and techniques, including artificial intelligence, gene editing, metabolic pathway assembly, and dynamic regulation have been used to design, construct, and optimize E. coli cell factories, which remarkably improved the efficiency for biotechnological production of chemicals. In this review, three key aspects for constructing E. coli cell factories, including pathway design, pathway assembly and regulation, and optimization of global cellular performance, are summarized. The technologies that have played important roles in metabolic engineering of E. coli, as well as their future applications, are discussed.
Artificial Intelligence ; Escherichia coli/genetics* ; Gene Editing ; Metabolic Engineering ; Metabolic Networks and Pathways/genetics*

新冠病毒感染疫情严重威胁着世界各国人民的生命健康。目前，对病毒感染的防治研究主要集中在抑制病毒与分子受体的结合上。AXL作为新发现的严重急性呼吸综合征冠状病毒2型（SARS-CoV-2）受体，在协助病毒感染人体呼吸系统中发挥着重要作用，是未来临床干预的潜在靶点。本研究对已发表的单细胞测序数据进行整理和分析，发现AXL在年轻人肺细胞中的表达水平明显高于老年人。人胚肺二倍体成纤维细胞（2BS）是衰老研究的公认细胞株。本文采用2BS细胞构建复制性细胞衰老模型，发现年轻细胞中AXL的蛋白水平明显高于衰老细胞，据此推测年轻人感染的风险可能更高，需要注意防护。我们发现一种羊栖菜褐藻多糖硫酸酯组分（SFW-3）可显著下调年轻2BS细胞中AXL的表达水平，表明SFW-3具有一定的抗SARS-CoV-2感染的研究价值，同时表明2BS细胞株也可作为潜在的SARS-CoV-2体外感染模型。
Humans ; SARS-CoV-2 ; Sargassum/metabolism* ; Diploidy ; Sulfates/metabolism* ; COVID-19 ; Polysaccharides/pharmacology* ; Lung

Objective: To establish a real-time fluorescence recombinase acid amplification (RAA) method for the detection of adenovirus type 3(HAdV-3)without extraction nucleic acid. Methods: According to the conserved sequence of adenovirus type 3 gene, a pair of primers and a probe were designed, and a real-time fluorescence RAA without extracting nucleic acid was established and optimizing the condition of DNA-free extraction. The sensitivity of the method was analyzed by a series of dilution and the specificity of the method was evaluated by detecting the original samples of other respiratory viruses. The clinical samples of HAdV-3 were detected and compared with the traditional real-time fluorescence quantitative PCR method for nucleic acid extraction. Results: The sensitivity of the real-time fluorescence RAA method was as high as that of qPCR in the detection of 10 series diluted HAdV-3 strains. The highest corresponding CT value of qPCR was 36.87. The sensitivity of the real-time fluorescence RAA method was similar to that of the real-time fluorescence quantitative PCR method . There was no cross-reaction to other common types of respiratory viruses. The two method were used to detect 56 clinical samples at the same time, and the result were completely consistent. Conclusions We provide the first report of the real-time fluorescent RAA assays for the detection of HAdV-3 without extracting nucleic acid and it has high sensitivity and specificity. Is suitable for rapid detection of HAdV-3 in clinical laboratories and on-site unite.