Publications by authors named "Jee Loon Foo"

Detecting alterations in plasmid structures is often performed using conventional molecular biology. However, these methods are laborious and time-consuming for studying the conditions inducing these mutations, which prevent real-time access to cell heterogeneity during bioproduction. In this work, we propose combining both flow cytometry and fluorescence-activated cell sorting, integrated with mechanistic modelling to study conditions that lead to plasmid recombination using a limonene-producing microbial system as a case study.

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Benzylisoquinoline alkaloids (BIAs) are a class of natural compounds found in plants of the family, known for their diverse pharmacological activities. However, the extraction yields of BIAs from plants are limited, and the cost of chemical synthesis is prohibitively high. Recent advancements in systems metabolic engineering and genomics have made it feasible to use microbes as bioreactors for BIAs production.

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Article Synopsis
  • The commentary argues for eco-friendly, bio-based solutions in chemical production using renewable resources to tackle urgent environmental issues.
  • It focuses on advanced metabolic engineering and the use of microbial consortia to improve the conversion of various renewable feedstocks, such as agricultural waste and industrial by-products, into valuable chemicals.
  • The article calls for a significant shift in sustainable biomanufacturing practices to support a circular bioeconomy and reduce environmental impacts globally.
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This study introduces a synthetic biology approach that reprograms the yeast mating-type switching mechanism for tunable cell differentiation, facilitating synthetic microbial consortia formation and cooperativity. The underlying mechanism was engineered into a genetic logic gate capable of inducing asymmetric sexual differentiation within a haploid yeast population, resulting in a consortium characterized by mating-type heterogeneity and tunable population composition. The utility of this approach in microbial consortia cooperativity was demonstrated through the sequential conversion of xylan into xylose, employing haploids of opposite mating types each expressing a different enzyme of the xylanolytic pathway.

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Chromosome-level design-build-test-learn cycles (chrDBTLs) allow systematic combinatorial reconfiguration of chromosomes with ease. Here, we established chrDBTL with a redesigned synthetic chromosome , . We designed and built to harbor strategically inserted features, modified elements, and synonymously recoded genes throughout the chromosome.

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Since its inception, synthetic biology has overcome many technical barriers but is at a crossroads for high-precision biological design. Devising ways to fully utilize big biological data may be the key to achieving greater heights in synthetic biology.

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Nucleic acid detection is crucial for monitoring diseases for which rapid, sensitive, and easy-to-deploy diagnostic tools are needed. CRISPR-based technologies can potentially fulfill this need for nucleic acid detection. However, their widespread use has been restricted by the requirement of a protospacer adjacent motif in the target and extensive guide RNA optimization.

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Article Synopsis
  • Fluorescent proteins are essential for tracking gene expression and protein localization in cells, especially in model organisms like yeast.
  • To improve the use of fluorescent proteins, researchers created destabilized versions of green and cyan proteins, but faced challenges with their overlapping light spectra.
  • The study reports the development of four new destabilized red fluorescent proteins by linking them to specific degrons, offering varied fluorescence lifetimes and intensities, which enhances the toolkit for studying cellular activities.
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Biosensors can be used for real-time monitoring of metabolites and high-throughput screening of producer strains. Use of biosensors has facilitated strain engineering to efficiently produce value-added compounds. Following our recent work on the production of short branched-chain fatty acids (SBCFAs) in engineered , here we harnessed a weak organic acid transporter Pdr12p, engineered a whole-cell biosensor to detect exogenous and intracellular SBCFAs and optimized the biosensor's performance by varying expression.

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Monoterpenoids are an important class of natural products that are derived from the condensation of two five‑carbon isoprene subunits. They are widely used for flavouring, fragrances, colourants, cosmetics, fuels, chemicals, and pharmaceuticals in various industries. They can also serve as precursors for the production of many industrially important products.

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Background: In biological cells, promoters drive gene expression by specific binding of RNA polymerase. They determine the starting position, timing and level of gene expression. Therefore, rational fine-tuning of promoters to regulate the expression levels of target genes for optimizing biosynthetic pathways in metabolic engineering has recently become an active area of research.

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Limonene is an important plant natural product widely used in food and cosmetics production as well as in the pharmaceutical and chemical industries. However, low efficiency of plant extraction and high energy consumption in chemical synthesis limit the sustainability of industrial limonene production. Recently, the advancement of metabolic engineering and synthetic biology has facilitated the engineering of microbes into microbial cell factories for producing limonene.

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Article Synopsis
  • * Engineering microorganisms to efficiently produce aldehydes provides a sustainable method for creating chemical precursors and their derivatives.
  • * Researchers successfully improved aldehyde production by modifying enzymes and removing competing pathways, leading to the highest reported production levels of aliphatic aldehydes and alkenes/alkanes in this field.
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  • Researchers are exploring a sustainable approach to produce pure -lipoic acid using engineered yeast, which can reduce the need for toxic chemicals.
  • By gen engineering yeast to enhance specific pathways, including overexpressing a key enzyme for releasing free -lipoic acid, the study achieved a significant increase in production, paving the way for greener methods of synthesizing this valuable compound.
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Carboxylic acids contain carboxyl groups that can undergo a wide range of chemical transformation. Therefore, they serve as key platform chemicals for the production of high value-added industrial products. Currently, the majority of carboxylic acid platform chemicals is produced predominantly through traditional chemical synthesis.

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Living organisms evolve complex genetic networks to interact with the environment. Due to the rapid development of synthetic biology, various modularized genetic parts and units have been identified from these networks. They have been employed to construct synthetic genetic circuits, including toggle switches, oscillators, feedback loops and Boolean logic gates.

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Cyanobacteria are of great importance to Earth's ecology. Due to their capability in photosynthesis and C1 metabolism, they are ideal microbial chassis that can be engineered for direct conversion of carbon dioxide and solar energy into biofuels and biochemicals. Facilitated by the elucidation of the basic biology of the photoautotrophic microbes and rapid advances in synthetic biology, genetic toolkits have been developed to enable implementation of nonnatural functionalities in engineered cyanobacteria.

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Synthetic biologists construct biological components and systems to look into biological phenomena and drive a myriad of practical applications that aim to tackle current global challenges in energy, healthcare and the environment. While most tools have been established in bacteria, particularly Escherichia coli, recent years have seen parallel developments in the model yeast strain Saccharomyces cerevisiae, one of the most well-understood eukaryotic biological system. Here, we outline the latest advances in yeast synthetic biology tools based on a framework of abstraction hierarchies of parts, circuits and genomes.

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Living organisms have evolved over millions of years to fine tune their metabolism to create efficient pathways for producing metabolites necessary for their survival. Advancement in the field of synthetic biology has enabled the exploitation of these metabolic pathways for the production of desired compounds by creating microbial cell factories through metabolic engineering, thus providing sustainable routes to obtain value-added chemicals. Following the past success in metabolic engineering, there is increasing interest in diversifying natural metabolic pathways to construct non-natural biosynthesis routes, thereby creating possibilities for producing novel valuable compounds that are non-natural or without elucidated biosynthesis pathways.

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Microbiomes exist in all ecosystems and are composed of diverse microbial communities. Perturbation to microbiomes brings about undesirable phenotypes in the hosts, resulting in diseases and disorders, and disturbs the balance of the associated ecosystems. Engineering of microbiomes can be used to modify structures of the microbiota and restore ecological balance.

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Short branched-chain fatty acids (SBCFAs, C4-6) are versatile platform intermediates for the production of value-added products in the chemical industry. Currently, SBCFAs are mainly synthesized chemically, which can be costly and may cause environmental pollution. In order to develop an economical and environmentally friendly route for SBCFA production, we engineered Saccharomyces cerevisiae, a model eukaryotic microorganism of industrial significance, for the overproduction of SBCFAs.

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  • * This study focuses on engineering the yeast Saccharomyces cerevisiae to convert free fatty acids into alkanes, using specific enzymes from rice and cyanobacteria to facilitate this transformation.
  • * Results demonstrate that this engineered yeast can efficiently produce alkanes from both external fatty acids and simple sugars, potentially paving the way for more sustainable biofuel production methods.
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Fatty aldehydes and alcohols are valuable precursors used in the industrial manufacturing of a myriad of specialty products. Herein, we demonstrate the de novo production of odd chain-length fatty aldehydes and fatty alcohols in Saccharomyces cerevisiae by expressing a novel biosynthetic pathway involving cytosolic thioesterase, rice α-dioxygenase and endogenous aldehyde reductases. We attained production titers of ∼20 mg/l fatty aldehydes and ∼20 mg/l fatty alcohols in shake flask cultures after 48 and 60 h respectively without extensive fine-tuning of metabolic fluxes.

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Unlabelled: Engineering microbial hosts for the production of fungible fuels requires mitigation of limitations posed on the production capacity. One such limitation arises from the inherent toxicity of solvent-like biofuel compounds to production strains, such as Escherichia coli. Here we show the importance of host engineering for the production of short-chain alcohols by studying the overexpression of genes upregulated in response to exogenous isopentenol.

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