Potential impact of synthetic biology on the development of microbial systems for the production of renewable fuels and chemicals
ABSTRACT Synthetic biology leverages advances in computational biology, molecular biology, protein engineering, and systems biology to design, synthesize, and assemble genetic elements for manipulating cell phenotypes. This emerging field is founded on a vast amount of gene sequence data available in public databases and our ability to rapidly and inexpensively synthesize DNA fragments of sufficient length to encode full-length genes, enzymes, metabolic pathways, and even entire genomes. Several thousand genetic elements encoding enzymes, reporters, repressors, activators, promoters, terminators, ribosome binding sites, signaling devices, and measurement systems are now available for engineering microbes. In addition to facilitating rational design, these new tools allow us to create and harness genetic diversity in combinatorial approaches to rapidly optimize metabolic pathways. As such, synthetic biology holds great promise for accelerating the development of microbial systems for the production of renewable fuels and chemicals.
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ABSTRACT: Full text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3665214/ Green microalgae for several decades have been produced for commercial exploitation, with applications ranging from health food for human consumption, aquaculture and animal feed, to coloring agents, cosmetics and others. Several products from green algae which are used today consist of secondary metabolites that can be extracted from the algal biomass. The best known examples are the carotenoids astaxanthin and β-carotene, which are used as coloring agents and for health-promoting purposes. Many species of green algae are able to produce valuable metabolites for different uses; examples are antioxidants, several different carotenoids, polyunsaturated fatty acids, vitamins, anticancer and antiviral drugs. In many cases, these substances are secondary metabolites that are produced when the algae are exposed to stress conditions linked to nutrient deprivation, light intensity, temperature, salinity and pH. In other cases, the metabolites have been detected in algae grown under optimal conditions, and little is known about optimization of the production of each product, or the effects of stress conditions on their production. Some green algae have shown the ability to produce significant amounts of hydrogen gas during sulfur deprivation, a process which is currently studied extensively worldwide. At the moment, the majority of research in this field has focused on the model organism, Chlamydomonas reinhardtii, but other species of green algae also have this ability. Currently there is little information available regarding the possibility for producing hydrogen and other valuable metabolites in the same process. This study aims to explore which stress conditions are known to induce the production of different valuable products in comparison to stress reactions leading to hydrogen production. Wild type species of green microalgae with known ability to produce high amounts of certain valuable metabolites are listed and linked to species with ability to produce hydrogen during general anaerobic conditions, and during sulfur deprivation. Species used today for commercial purposes are also described. This information is analyzed in order to form a basis for selection of wild type species for a future multi-step process, where hydrogen production from solar energy is combined with the production of valuable metabolites and other commercial uses of the algal biomass.Critical Reviews in Biotechnology 07/2012; 33(2). DOI:10.3109/07388551.2012.681625 · 7.84 Impact Factor
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ABSTRACT: a b s t r a c t Felled oil palm trunk (OPT) (25 years old) is an abundant biomass in Southern Thailand. The OPT composition was 31.28e42.85% cellulose, 19.73e25.56% hemicellulose, 10.74e18.47% lignin, 1.63e2.25% protein, 1.60e1.83% fat, 1.12e1.35% ash and trace amount of minerals (0.01e0.40%). Oil palm sap extracted from OPT was found to contain 15.72 g/L glucose, 2.25 g/L xylose, and 0.086 g/L arabinose. A total of twenty samples from hot springs (45e75 C and pH 6.5e8.4), oil palm sap and palm oil mill effluent were enriched for isolation of hydrogen-producing bacteria. The highest hydrogen-producing strain was isolated from oil palm sap and identified as Clostridium beijerinckii PS-3 using biochemical test and 16S rRNA gene analysis. Among various carbon sources tested, glucose, xylose, starch and cellulose were the preferred substrates for hydrogen production. The strain PS-3 could produce the maximum hydrogen yield of 140.9 ml H 2 /g total sugar and the cumu-lative hydrogen production of 1973 ml/L-oil palm sap. Therefore, C. beijerinckii PS-3 is a potential candidate for fermentative hydrogen production from mixed sugars of the oil palm sap.International Journal of Hydrogen Energy 10/2011; 36(21):14086-14092. DOI:10.1016/j.ijhydene.2011.04.143 · 2.93 Impact Factor
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ABSTRACT: We describe a highly efficient in vivo DNA assembly method, multiple-round in vivo site-specific assembly (MISSA), which facilitates plant multiple-gene transformation. MISSA is based on conjugational transfer, which is driven by donor strains, and two in vivo site-specific recombination events, which are mediated by inducible Cre recombinase and phage lambda site-specific recombination proteins in recipient strains, to enable in vivo transfer and in vivo assembly of multiple transgenic DNA. The assembly reactions can be performed circularly and iteratively through alternate use of the two specially designed donor vectors. As proof-of-principle experiments, we constructed a few plant multigene binary vectors. One of these vectors was generated by 15 rounds of MISSA reactions and was confirmed in transgenic Arabidopsis (Arabidopsis thaliana). As MISSA simplifies the tedious and time-consuming in vitro manipulations to a simple mixing of bacterial strains, it will greatly save time, effort, and expense associated with the assembly of multiple transgenic or synthetic DNA. The principle that underlies MISSA is applicable to engineering polygenic traits, biosynthetic pathways, or protein complexes in all organisms, such as Escherichia coli, yeast, plants, and animals. MISSA also has potential applications in synthetic biology, whether for basic theory or for applied biotechnology, aiming at the assembly of genetic pathways for the production of biofuels, pharmaceuticals, and industrial compounds from natural or synthetic DNA.Plant physiology 03/2010; 153(1):41-51. DOI:10.1104/pp.109.152249 · 7.39 Impact Factor