Tag Archives: SynBio

Engineering yeast endosymbionts as a step toward the evolution of mitochondria

Angad P. MehtaLubica SupekovaJian-Hua ChenKersi PestonjamaspPaul WebsterYeonjin KoScott C. HendersonGerry McDermottFrantisek Supek, and Peter G. Schultz

Endosymbiotic theory suggests that mitochondria evolved from free-living prokaryotes which entered the host cell and were retained as endosymbionts. Here, we model this earliest stage of the endosymbiotic theory of mitochondrial evolution by engineering endosymbiosis between two genetically tractable model organisms, Escherichia coli and Saccharomyces cerevisiae. Read more

Biosynthesis of the antibiotic nonribosomal peptide penicillin in baker’s yeast

Ali R. Awan, Benjamin A. Blount, David J. Bell, William M. Shaw, Jack C.H. Ho, Robert M. McKiernan & Tom Ellis

Fungi are a valuable source of enzymatic diversity and therapeutic natural products including antibiotics. Here we engineer the baker’s yeast Saccharomyces cerevisiae to produce and secrete the antibiotic penicillin, a beta-lactam nonribosomal peptide, by taking genes from a filamentous fungus and directing their efficient expression and subcellular localization. Using synthetic biology tools combined with long-read DNA sequencing, we optimize productivity by 50-fold to produce bioactive yields that allow spent S. cerevisiae growth media to have antibacterial action against Streptococcus bacteria. This work demonstrates that S. cerevisiae can be engineered to perform the complex biosynthesis of multicellular fungi, opening up the possibility of using yeast to accelerate rational engineering of nonribosomal peptide antibiotics.


Read the full article in Nature Communications

Whole-cell biocatalysts by design

Baixue Lin and Yong Tao

Whole-cell biocatalysts provide unique advantages and have been widely used for the efficient biosynthesis of value-added fine and bulk chemicals, as well as pharmaceutically active ingredients. What is more, advances in synthetic biology and metabolic engineering, together with the rapid development of molecular genetic tools, have brought about a renaissance of whole-cell biocatalysis. These rapid advancements mean that whole-cell biocatalysts can increasingly be rationally designed. Genes of heterologous enzymes or synthetic pathways are increasingly being introduced into microbial hosts, and depending on the complexity of the synthetic pathway or the target products, they can enable the production of value-added chemicals from cheap feedstock. Metabolic engineering and synthetic biology efforts aimed at optimizing the existing microbial cell factories concentrate on improving heterologous pathway flux, precursor supply, and cofactor balance, as well as other aspects of cellular metabolism, to enhance the efficiency of biocatalysts. In the present review, we take a critical look at recent developments in whole-cell biocatalysis, with an emphasis on strategies applied to designing and optimizing the organisms that are increasingly modified for efficient production of chemicals.


Read the full article in Microbial Cell Factories

Large scale validation of an efficient CRISPR/Cas-based multi gene editing protocol in Escherichia coli

Francesca Zerbini, Ilaria Zanella, Davide Fraccascia, Enrico König, Carmela Irene, Luca F. Frattini, Michele Tomasi, Laura Fantappiè, Luisa Ganfini, Elena Caproni, Matteo Parri, Alberto Grandi and Guido Grandi

The exploitation of the CRISPR/Cas9 machinery coupled to lambda (λ) recombinase-mediated homologous recombination (recombineering) is becoming the method of choice for genome editing in E. coli. First proposed by Jiang and co-workers, the strategy has been subsequently fine-tuned by several authors who demonstrated, by using few selected loci, that the efficiency of mutagenesis (number of mutant colonies over total number of colonies analyzed) can be extremely high (up to 100%). However, from published data it is difficult to appreciate the robustness of the technology, defined as the number of successfully mutated loci over the total number of targeted loci. This information is particularly relevant in high-throughput genome editing, where repetition of experiments to rescue missing mutants would be impractical. This work describes a “brute force” validation activity, which culminated in the definition of a robust, simple and rapid protocol for single or multiple gene deletions.


Read the full article Microbial Cell Factories

Microbial response to environmental stresses: from fundamental mechanisms to practical applications

Ningzi Guan, Jianghua Li, Hyun-dong Shin, Guocheng Du, Jian Chen, Long Liu

Environmental stresses are usually active during the process of microbial fermentation and have significant influence on microbial physiology. Microorganisms have developed a series of strategies to resist environmental stresses. For instance, they maintain the integrity and fluidity of cell membranes by modulating their structure and composition, and the permeability and activities of transporters are adjusted to control nutrient transport and ion exchange. Certain transcription factors are activated to enhance gene expression, and specific signal transduction pathways are induced to adapt to environmental changes. Besides, microbial cells also have well-established repair mechanisms that protect their macromolecules against damages inflicted by environmental stresses. Oxidative, hyperosmotic, thermal, acid, and organic solvent stresses are significant in microbial fermentation. In this review, we summarize the modus operandi by which these stresses act on cellular components, as well as the corresponding resistance mechanisms developed by microorganisms. Then, we discuss the applications of these stress resistance mechanisms on the production of industrially important chemicals. Finally, we prospect the application of systems biology and synthetic biology in the identification of resistant mechanisms and improvement of metabolic robustness of microorganisms in environmental stresses.


Read the full article in Applied Microbiology and Biotechnology

Development of a fast and easy method for Escherichia coli genome editing with CRISPR/Cas9

Dongdong Zhao, Shenli Yuan, Bin Xiong, Hongnian Sun, Lijun Ye, Jing Li, Xueli Zhang and Changhao Bi

Background
Microbial genome editing is a powerful tool to modify chromosome in way of deletion, insertion or replacement, which is one of the most important techniques in metabolic engineering research. The emergence of CRISPR/Cas9 technique inspires various genomic editing methods. Read more

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