Author Archives: CBMNet

Systems Analyses Reveal the Resilience of Escherichia coli Physiology during Accumulation and Export of the Nonnative Organic Acid Citramalate

Joseph Webb, Vicki Springthorpe, Luca Rossoni, David-Paul Minde, Swen Langer, Heather Walker, Amias Alstrom-Moore, Tony Larson, Kathryn Lilley, Graham Eastham, Gill Stephens, Gavin H. Thomas, David J. Kelly, Jeffrey Green

Citramalate is an attractive biotechnology target because it is a precursor of methylmethacrylate, which is used to manufacture Perspex and other high-value products. Engineered E. coli strains are able to produce high titers of citramalate, despite having to express a foreign enzyme and tolerate the presence of a nonnative biochemical. A systems analysis of the citramalate fermentation was undertaken to uncover the reasons underpinning its productivity. This showed that E. coli readily adjusts to the redirection of metabolic resources toward recombinant protein and citramalate production and suggests that E. coli is an excellent chassis for manufacturing similar small, polar, foreign molecules. Read more

Proteomic Profiling, Transcription Factor Modeling, and Genomics of Evolved Tolerant Strains Elucidate Mechanisms of Vanillin Toxicity in Escherichia coli

Calum A. Pattrick, Joseph P. Webb, Jeffrey Green, Roy R. Chaudhuri, Mark O. Collins, David J. Kelly

A particular problem for the biotechnological production of many of the valuable chemicals that we are now able to manufacture in bacterial cells is that these products often poison the cells producing them. Solutions to improve product yields or alleviate such toxicity using the techniques of modern molecular biology first require a detailed understanding of the mechanisms of product toxicity. Here we have studied the economically important flavor compound vanillin, an aromatic aldehyde that exerts significant toxic effects on bacterial cells. We used high-resolution protein abundance analysis as a starting point to determine which proteins are upregulated and which are downregulated by growth with vanillin, followed by gene expression and mutant studies to understand the mechanism of the response. In a second approach, we evolved bacterial strains with higher vanillin tolerance. Their genome sequences have yielded novel insights into vanillin tolerance that are complementary to the proteomics data set. Read more

First wave of Future Leaders Fellowships Announced

In May 2019, the Science Minister Chris Skidmore announced the first wave of Future Leaders Fellowships, helping researchers and innovators become world-leaders in their fields. 41 Early Career Researchers from universities across the UK will each benefit from a share of £40 million towards cutting edge research addressing fundamental global issues, including tackling climate change and revolutionising travel across cities. Read more

Adaptive laboratory evolution reveals general and specific chemical tolerance mechanisms and enhances biochemical production

Rebecca M. Lennen, Kristian Jensen, Elsayed T. Mohammed, Sailesh Malla, Rosa A. Börner, Ksenia Chekina, Emre Özdemir, Ida Bonde, Anna Koza, Jérôme Maury, Lasse E. Pedersen, Lars Y. Schöning, Nikolaus Sonnenschein, Bernhard O. Palsson, Morten O.A. Sommer, Adam M. Feist, Alex T. Nielsen, Markus J. Herrgård

Tolerance to high product concentrations is a major barrier to achieving economically viable processes for bio-based chemical production. Chemical tolerance mechanisms are often unknown, thus their rational design is not achievable. To reveal unknown tolerance mechanisms we used an automated platform to evolve Escherichia coli to grow in previously toxic concentrations of 11 chemicals that have applications as polymer precursors, chemical intermediates, or biofuels. Read more

Engineering Corynebacterium glutamicum to produce the biogasoline isopentenol from plant biomass hydrolysates

Yusuke Sasaki, Thomas Eng, Robin A. Herbert, Jessica Trinh, Yan Chen, Alberto Rodriguez, John Gladden, Blake A. Simmons, Christopher J. Petzold and Aindrila Mukhopadhyay

Background: Many microbes used for the rapid discovery and development of metabolic pathways have sensitivities to final products and process reagents. Isopentenol (3-methyl-3-buten-1-ol), a biogasoline candidate, has an established heterologous gene pathway but is toxic to several microbial hosts. Reagents used in the pretreatment of plant biomass, such as ionic liquids, also inhibit growth of many host strains. We explored the use of Corynebacterium glutamicum as an alternative host to address these constraints. Read more

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