Biofuels and biopharmaceuticals meet: scientists develop safe and inexpensive alternative to antibiotics in production of biotech products
Researchers at Sweden's Karolinska Institute and at the Royal Veterinary College (RVC) in London have developed a system that eliminates the need for antibiotics and resistance genes in the engineering of industrial and medical products. The method involves safer, less costly alternatives and is well suited for industrial production of many types of biofuels and biopharmaceuticals. The research has been published as an open access article in BMC Biotechnology.
Antibiotic resistance genes are widely used for selection of recombinant bacteria for use in biotechnology, but their use risks contributing to the spread of antibiotic resistance, particularly as biotechnology products move into the environment and the clinic. In particular, the practice is inappropriate for some intrinsically resistant bacteria and in vaccine production, and costly for industrial scale production. Non-antibiotic systems are available, but require mutant host strains, defined media or expensive reagents.
Gene targeting is the insertion of DNA into specific sites or genes within the genome of selected cells in order to alter gene expression for a particular purpose.
While working on gene targeting in bacteria, the researchers discovered that a well-known interaction between a cell membrane synthesis gene and the biocide triclosan could be exploited for strain selection. Surprisingly, triclosan selection performs better than conventional antibiotic selection:
The new cloning vector, pFab, enabled selection by triclosan at 1 μM. Interestingly, pFab out-performed the parent pUC19-ampicillin system in cell growth, plasmid stability and plasmid yield. Also, pFab was toxic to host cells in a way that was reversed by triclosan. Therefore, pFab and triclosan are toxic when used alone but in combination they enhance growth and plasmid production through a gene-inhibitor interaction.
The fabI-triclosan model system thus provides an alternative plasmid selection method based on essential gene over-expression, without the use of antibiotic-resistance genes and conventional antibiotics.
The research was carried out with Dr Shan Goh of the Department of Cell and Molecular Biology of the Karolinska Institute, Stockholm.
References:
Shan Goh and Liam Good, "Plasmid selection in Escherichia coli using an endogenous essential gene marker", BMC Biotechnology 2008, 8:61, doi:10.1186/1472-6750-8-61.
Antibiotic resistance genes are widely used for selection of recombinant bacteria for use in biotechnology, but their use risks contributing to the spread of antibiotic resistance, particularly as biotechnology products move into the environment and the clinic. In particular, the practice is inappropriate for some intrinsically resistant bacteria and in vaccine production, and costly for industrial scale production. Non-antibiotic systems are available, but require mutant host strains, defined media or expensive reagents.
Gene targeting is the insertion of DNA into specific sites or genes within the genome of selected cells in order to alter gene expression for a particular purpose.
While working on gene targeting in bacteria, the researchers discovered that a well-known interaction between a cell membrane synthesis gene and the biocide triclosan could be exploited for strain selection. Surprisingly, triclosan selection performs better than conventional antibiotic selection:
We think this simple technology is well suited for industrial scale fermentations that produce a range of valuable products, including bio-fuels and bio-pharmaceuticals. More importantly, the new system is relatively safe and inexpensive, because the gene is native in all bacteria and triclosan is approved for use in many household applications. - Dr Liam Good, Royal Veterinary College and lead researcher on the projectenergy :: sustainability :: biomass :: bioenergy :: biofuels :: bioproducts :: biopharmaceuticals :: biotechnology ::
The new cloning vector, pFab, enabled selection by triclosan at 1 μM. Interestingly, pFab out-performed the parent pUC19-ampicillin system in cell growth, plasmid stability and plasmid yield. Also, pFab was toxic to host cells in a way that was reversed by triclosan. Therefore, pFab and triclosan are toxic when used alone but in combination they enhance growth and plasmid production through a gene-inhibitor interaction.
The fabI-triclosan model system thus provides an alternative plasmid selection method based on essential gene over-expression, without the use of antibiotic-resistance genes and conventional antibiotics.
The research was carried out with Dr Shan Goh of the Department of Cell and Molecular Biology of the Karolinska Institute, Stockholm.
References:
Shan Goh and Liam Good, "Plasmid selection in Escherichia coli using an endogenous essential gene marker", BMC Biotechnology 2008, 8:61, doi:10.1186/1472-6750-8-61.
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