Functional expansion of the natural inorganic phosphorus starvation response system in Escherichia coli.

Phosphorus, an indispensable nutrient, plays an essential role in cell composition, metabolism, and signal transduction. When inorganic phosphorus (Pi) is scarce, the Pi starvation response in E. coli is activated to increase phosphorus acquisition and drive the cells into a non-growing state to reduce phosphorus consumption. In the six decades of research history, the initiation, output, and shutdown processes of the Pi starvation response have been extensively studied. Simultaneously, Pi starvation has been used in biosensor development, recombinant protein production, and natural product biosynthesis. In this review, we focus on the output process and the applications of the Pi starvation response that have not been summarized before. Meanwhile, based on the current status of mechanistic studies and applications, we propose practical strategies to develop the natural Pi starvation response into a multifunctional and standardized regulatory system in four aspects, including response threshold, temporal expression, intensity range, and bifunctional regulation, which will contribute to its broader application in more fields such as industrial production, medical analysis, and environmental protection.

Synergetic utilization of glucose and glycerol for efficient myo-inositol biosynthesis.

myo-Inositol (MI) as a dietary supplement can provide various health benefits. One major challenge to its efficient biosynthesis is to achieve proper distribution of carbon flux between growth and production. Herein, this challenge was overcome by synergetic utilization of glucose and glycerol. Specifically, glycerol was catabolized to support cell growth while glucose was conserved as the building block for MI production. Growth and production were coupled via the phosphotransferase system, and both modules were optimized to achieve efficient production. First, the optimal enzyme combination was established for the production module. It was observed that enhancing the production module resulted in both increased MI production and better cell growth. In addition, glucose was shown to inhibit glycerol utilization via carbon catabolite repression and the inhibition was released by over-expressing glycerol kinase. Furthermore, the inducible promoter was replaced by strong constitutive promoters to avoid inducer use. With these efforts, the final strain produced MI with both high titer and yield. In fed-batch cultivation, 76 g/L of MI was produced, showing scale-up potential. This study provides a promising strategy to achieve rational distribution of carbon flux.

Recent advances in microbial production of aromatic natural products and their derivatives.

Aromatic natural products represent a diverse class of chemicals with great industrial significance. Usually, they serve as the building blocks for production of various polymers, esters, fibers, nutraceuticals, and pharmaceuticals. However, industrial synthesis of aromatic natural products still relies heavily on petroleum-based chemical processes, which are not sustainable and eco-friendly. In the past decades, construction of microbial cell factories that are able to efficiently convert renewable carbon sources into value-added products has made significant progress. This review highlights the recent advances in metabolic engineering efforts for biological production of aromatic natural products and their derivatives. Many novel pathways, enzymes, and products were reported in the literatures but have not yet detailed and informative viewed so far. Our goals are to provide a landscape of current works and present guidelines to address future challenges in biosynthesis of aromatic natural products and their derivatives using engineered microorganisms.

Synthesis of chemicals by metabolic engineering of microbes.

Metabolic engineering is a powerful tool for the sustainable production of chemicals. Over the years, the exploration of microbial, animal and plant metabolism has generated a wealth of valuable genetic information. The prudent application of this knowledge on cellular metabolism and biochemistry has enabled the construction of novel metabolic pathways that do not exist in nature or enhance existing ones. The hand in hand development of computational technology, protein science and genetic manipulation tools has formed the basis of powerful emerging technologies that make the production of green chemicals and fuels a reality. Microbial production of chemicals is more feasible compared to plant and animal systems, due to simpler genetic make-up and amenable growth rates. Here, we summarize the recent progress in the synthesis of biofuels, value added chemicals, pharmaceuticals and nutraceuticals via metabolic engineering of microbes.

A new phenolic glucoside from the leaves of Heliciopsis lobata.

A new phenolic glucoside ester, 6'-E-(2''-methyl-2''-butenoyl) arbutin (1), was isolated from the leaves of Heliciopsis lobata. Its structure was elucidated by spectral analysis.