Publications by authors named "Xueqin Lv"

Keeping condensates in liquid-like states throughout the biosynthesis process in microbial cell factories remains an ongoing challenge. Here, we present a light-controlled phase regulator, which maintains the liquid-like features of synthetic condensates on demand throughout the biosynthesis process upon light induction, as demonstrated by various live cell-imaging techniques. Specifically, the tobacco etch virus (TEV) protease controlled by light cleaves intrinsically disordered proteins (IDPs) to alter their valency and concentration for controlled phase transition and programmable fluidity of cellular condensates.

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Terpenoids, also known as isoprenoids, represent the largest and most structurally diverse family of natural products, and their biosynthesis is closely related to cytochrome P450 enzymes (P450s). Given the limitations of direct extraction from natural resources, such as low productivity and environmental concerns, heterologous expression of P450s in microbial cell factories has emerged as a promising, efficient, and sustainable strategy for terpenoid production. The yeast expression system is a preferred selection for terpenoid synthesis because of its inner membrane system, which is required for eukaryotic P450 expression, and the inherent mevalonate pathway providing precursors for terpenoid synthesis.

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Multiscale modeling is a promising approach for understanding cellular behaviors. However, existing multiscale modeling tools require meticulously curated genome-scale metabolic models (GEMs) as inputs, limiting the broad applications of multiscale models due to complex and time-consuming construction processes. To this end, we developed a novel workflow named CarveAdornCurate (CAC) for de novo multiscale modeling.

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L-citrulline is a nonprotein amino acid that plays an important role in human health and has great market demand. Although microbial cell factories have been widely used for biosynthesis, there are still challenges such as genetic instability and low efficiency in the biosynthesis of L-citrulline. In this study, an efficient, plasmid-free, non-inducible L-citrulline-producing strain of BL21(DE3) was engineered by combined strategies.

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Inducible systems are crucial to metabolic engineering and synthetic biology, enabling organisms that function as biosensors and produce valuable compounds. However, almost all inducible systems are strain-specific, limiting comparative analyses and applications across strains rapidly. This study designed and presented a robust workflow for developing the cross-species inducible system.

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High sugar intake has become a global health concern due to its association with various diseases. Mogroside V (MG-V), a zero-calorie sweetener with multiple medical properties, is emerging as a promising sugar substitute. However, its application is hindered by low natural abundance and the inefficiency of conventional plant extraction methods.

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Developing efficient gene regulation tools is essential for optimizing microbial cell factories, but most existing tools only modulate gene expression at the transcriptional level. Regulation at the translational level provides a faster dynamic response, whereas developing a programmable, efficient and multiplexed translational regulation tool remains a challenge. Here, we have developed CRISPRi and CRISPRa systems based on hfCas13X that can regulate gene translation in Bacillus subtilis.

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Enhancing the protein content and production efficiency of is crucial as an alternative protein source. This study screened nongenetically modified yeast strains with high protein content for food ingredient production and explored the underlying mechanisms. Yeast protein levels were found to correlate with RNA, leading to a high-throughput screening method using RNA fluorescence and flow cytometry.

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2'-Fucosyllactose (2'-FL) is the most abundant human milk oligosaccharide and plays significant roles in gut microbiome balance, neural development, and immunoregulation. However, current fermentation schemes using multiple carbon sources increase production cost and metabolism burden. This study reported the development of an engineered Bacillus subtilis strain that produces 2'-FL using glucose as the sole carbon source.

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Generally, the metabolism in microbial organism is an intricate, spatiotemporal process that emerges from gene regulatory networks, which affects the efficiency of product biosynthesis. With the coming age of synthetic biology, spatiotemporal control systems have been explored as versatile strategies to promote product biosynthesis at both spatial and temporal levels. Meanwhile, the designer synthetic compartments provide new and promising approaches to engineerable spatiotemporal control systems to construct high-performance microbial cell factories.

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Article Synopsis
  • This study focuses on the increased production of 7-Dehydrocholesterol (7-DHC), a precursor for vitamin D3, through microbial fermentation techniques.
  • By expressing a particular enzyme and disrupting certain pathways, researchers achieved significant increases in 7-DHC yields, reaching a record 3.80 g/L in a large-scale fermenter within 24 hours.
  • The findings suggest potential for large-scale, cost-effective production methods for 7-DHC, opening doors for further research and commercial applications.
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Long non-coding RNAs were commonly viewed as non-coding elements. However, they are increasingly recognized for their ability to be translated into proteins, thereby playing a significant role in various cellular processes and diseases. With developments in biotechnology and computational algorithms, a range of novel approaches are being applied to investigate the translation of long non-coding RNA (lncRNAs).

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Lipid droplets (LDs) are specialized organelles that store neutral lipids to reduce the negative effects of lipotoxicity on cells. However, many neutral lipids are precursors for the synthesis of sterols and complex terpenoids, and this sequestration often greatly limits the efficient biosynthesis of sterols and complex terpenoids. In this study, taking 7-dehydrocholesterol (7-DHC) synthesis in Saccharomyces cerevisiae as an example, we revealed the blocking mechanism of LD sequestration on the efficient synthesis of metabolic products and found that LDs can sequester a significant amount of squalene, the precursor of 7-DHC, effectively preventing it from being directed toward the post-squalene pathway.

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Article Synopsis
  • This study aimed to enhance protein synthesis efficiency in Bacillus subtilis by using CRISPRi to regulate metabolism, focusing on repressing the odhA gene and overexpressing energy metabolism genes to improve cell growth.
  • The engineered B. subtilis showed increased growth rates and biomass yields—61.54% and 46.43% improvements, respectively—compared to standard B. subtilis 168.
  • The optimized system allowed for better protein production, achieving a secretory bovine alpha-lactalbumin titer of 1.02 mg/L and significant increases in the expression of intracellular and secretory proteins like GFP and α-amylase.
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Given the extensive heterogeneity and variability, understanding cellular functions and regulatory mechanisms through the analysis of multi-omics datasets becomes extremely challenging. Here, a comprehensive modeling framework of multi-omics machine learning and metabolic network models are proposed that covers various cellular biological processes across multiple scales. This model on an extensive normalized compendium of Bacillus subtilis is validated, which encompasses gene expression data from environmental perturbations, transcriptional regulation, signal transduction, protein translation, and growth measurements.

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Article Synopsis
  • There is a growing interest in using engineered condensates formed through liquid-liquid phase separation (LLPS) to gain control over cellular processes in prokaryotes, but creating these condensates is still challenging.
  • This study introduces a synthetic platform using artificial, disordered proteins to design specific condensates in the bacterium Bacillus subtilis, employing a method called the "stacking blocks" strategy.
  • The research shows that these engineered condensates can successfully sequester metabolic pathways, resulting in significant increases in biosynthesis and translation specificity, laying the groundwork for multifunctional condensates.
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Directed evolution seeks to evolve target genes at a rate far exceeding the natural mutation rate, thereby endowing cellular and enzymatic properties with desired traits. In vivo continuous directed evolution achieves these purposes by generating libraries within living cells, enabling a continuous cycle of mutant generation and selection, enhancing the exploration of gene variants. Continuous evolution has become powerful tools for unraveling evolution mechanism and improving cellular and enzymatic properties.

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Ovalbumin (OVA) is a high-quality protein for humans. Modifying microorganisms to produce proteins offers a solution to potential food protein shortages. In this study, OVA was expressed in .

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In recent years, genetic circuit-based regulation of metabolic flux in microbial cell factories has received significant attention. In this review, we describe a pipeline for the design and construction of genetic circuits for metabolic flux optimization. In particular, we summarize the recent advances in computationally assisted prediction of critical metabolic nodes and genetic circuit design automation.

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Menaquinone-7 (MK-7), a form of vitamin K2, supports bone health and prevents arterial calcification. Microbial fermentation for MK-7 production has attracted widespread attention because of its low cost and short production cycles. However, insufficient substrate supply, unbalanced precursor synthesis, and low catalytic efficiency of key enzymes severely limited the efficiency of MK-7 synthesis.

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Human lactoferrin (HLF), an essential nutrient found in breast milk, possesses antibacterial, anti-inflammatory, and immune-enhancing properties. In this study, the effects of three constitutive promoters (P, P, and P) and three inducible promoters (P, P, and P) on the expression of HLF were compared using G601 as the host strain. The results showed that the highest expression of HLF, reaching 651.

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3-Fucosyllactose (3-FL) is an important fucosylated human milk oligosaccharide (HMO) with biological functions such as promoting immunity and brain development. Therefore, the construction of microbial cell factories is a promising approach to synthesizing 3-FL from renewable feedstocks. In this study, a combinatorial engineering strategy was used to achieve efficient 3-FL production in .

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Betulinic acid (BA) is a lupane-type triterpenoid with potent anticancer and anti-HIV activities. Its great potential in clinical applications necessitates the development of an efficient strategy for BA synthesis. This study attempted to achieve efficient BA biosynthesis in using systematic metabolic engineering strategies.

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Article Synopsis
  • Strengthening gene expression in microbial cell factories is essential for efficient bioproduction in synthetic biology, with chromosomal multi-copy genes providing more stability than plasmid-based methods.
  • The study introduced a new system that uses a reversible switch and a combination of repressor and non-natural amino acids, allowing controlled gene amplification and editing while stabilizing gene copy numbers.
  • Implementing this system resulted in a 3-fold increase in gene expression and improved synthesis of -acetylneuraminic acid, demonstrating the potential for enhanced gene expression in metabolic engineering.
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5-Methyltetrahydrofolate (5-MTHF) is the sole active form of folate functioning in the human body and is widely used as a nutraceutical. Unlike the pollution from chemical synthesis, microbial synthesis enables green production of 5-MTHF. In this study, BL21 (DE3) was selected as the host.

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