Metagenics

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The word metagenics uses the prefix meta and the suffix gen. Literally, it means "the creation of something which creates". In the context of biotechnology, metagenics is the practice of engineering organisms to create a specific enzyme, protein, or other biochemicals from simpler starting materials. The genetic engineering of E. coli with the specific task of producing human insulin from starting amino acids is an example. E. coli has also been engineered to digest plant biomass and use it to produce hydrocarbons in order to synthesize biofuels. The applications of metagenics on E. coli also include higher alcohols, fatty-acid based chemicals and terpenes. [1]

Contents

Biofuels

The depletion of petroleum sources and increase in greenhouse gas emissions in the twenty and twenty-first centuries has been the driving factor behind the development of biofuels from microorganisms. E. coli is currently regarded as the best option for biofuel production because of the amount of knowledge available about its genome. The process converts biomass into fuels, and has proven successful on an industrial scale, with the United States having produced 6.4 billion gallons of bioethanol in 2007. Bioethenol is currently the front-runner for alternative fuel production and uses S.cerevisiae and Zymomonas mobilis to create ethanol through fermentation. However, maximum productivity is limited due to the fact that these organisms cannot use pentose sugars, leading to consideration of E.coli and Clostridia. E.coli is capable of producing ethanol under anaerobic conditions through metabolizing glucose into two moles of formate, two moles of acetate, and one mole of ethanol. While bioethanol has proved to be a successful alternative fuel source on an industrial scale, it also has its shortcomings, namely, its low energy density, high vapor pressure, and hygroscopicity. Current alternatives to bioethanol include biobutanol, biodiesel, propanol, and synthetic hydrocarbons. [2] The most common form of biodiesels is fatty acid methyl esters and current synthesis strategies involve transesterification of triacylglycerols from plant oils. However, plant oils have a major limitation in availability of oil-seed supplies at competitive prices, leading to an interest in direct synthesis of fatty acid methyl esters in bacteria. This process bypasses transesterification, leading to higher energy yields and lower production cost. [3] One of the principal obstacles in production of viable biofuels is that the maximum blend ratio of biofuel to petroleum is between 10% and 20%, Current biofuels are not compatible with high-performance, low-emission engines and costly changes in infrastructure and engine remodeling would be required. A University of Exeter study sought to overcome this obstacle through production of biofuels that can replace current fossil fuels through sustainable means, namely, the production of n-alkanes, iso-alkanes, and n-alkenes, as these are the hydrocarbons that compose current retail transport fuels. The study found suitable substrates for production of the aforementioned hydrocarbons by means of the P. luminescens fatty acid reductase (FAR) complex. [4] A study published in Biotechnology for Biofuels used S. cerevisiae to produce short- and branched-chain alkyl esters biodiesel through metabolic engineering. Negative regulators for the INO1 gene, Rpd3 and Opi1 were deleted to boost S. cerevisiae's ability to produce fatty acid esters. To increase the production of alcohol precursors, five isobutanol pathway enzymes were overexpressed. [5]

Insulin Production

Increase in the demand for recombinant insulin can be explained by an increase in the number of diabetic patients globally, as well as alternative delivery methods such as inhalation and oral routes, which require higher doses. [6] Through the use of recombinant DNA technology, E. coli can be used for the production of human insulin. The biosynthesis of insulin within the human body confers a significant advantage over bovine or porcine synthesis, which are often immunogenic in diabetic patients. [7] To accomplish this, synthetic genes for human insulin are fused with the β-galactosidase gene of E.coli, where they undergo transcription and ultimately translation into proteins. [8] The limiting factor for the use of microorganisms like E. coli in biosynthesis of gene products like insulin is time, yet due to advancements in the synthesis of oligonucleotides and liquid chromatography, the production time needed for DNA fragments has greatly decreased. [9] Recombinant human insulin was first approved for clinical trials in 1980. At this time the A and B chains of insulin were produced separately and then chemically joined. [10] Joining of the two chains was often carried out through air oxidation with low efficiency. A 1978 study by Goedell et al. successfully accomplished correct joining of the A and B chains through S-sulfonated derivatives and an excess of the A chain, resulting in 50-80% correct joining. [8] Recent advances have allowed the chains to be synthesized together by inserting the human proinsulin gene into E. coli cells, which produce proinsulin through fermentation. [10]

Further reading

Related Research Articles

<span class="mw-page-title-main">Biofuel</span> Type of biological fuel produced from biomass from which energy is derived

Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. Biofuel can be produced from plants or from agricultural, domestic or industrial biowaste.

<span class="mw-page-title-main">Recombinant DNA</span> DNA molecules formed by human agency at a molecular level generating novel DNA sequences

Recombinant DNA (rDNA) molecules are DNA molecules formed by laboratory methods of genetic recombination that bring together genetic material from multiple sources, creating sequences that would not otherwise be found in the genome.

Fatty acid methyl esters (FAME) are a type of fatty acid ester that are derived by transesterification of fats with methanol. The molecules in biodiesel are primarily FAME, usually obtained from vegetable oils by transesterification. They are used to produce detergents and biodiesel. FAME are typically produced by an alkali-catalyzed reaction between fats and methanol in the presence of base such as sodium hydroxide, sodium methoxide or potassium hydroxide. One of the reasons for FAME use in biodiesel instead of free fatty acids is to nullify any corrosion that free fatty acids would cause to the metals of engines, production facilities and so forth. Free fatty acids are only mildly acidic, but in time can cause cumulative corrosion unlike their esters. As an improved quality, FAMEs also usually have about 12-15 units higher cetane number than their unesterified counterparts.

<span class="mw-page-title-main">Metabolic engineering</span>

Metabolic engineering is the practice of optimizing genetic and regulatory processes within cells to increase the cell's production of a certain substance. These processes are chemical networks that use a series of biochemical reactions and enzymes that allow cells to convert raw materials into molecules necessary for the cell's survival. Metabolic engineering specifically seeks to mathematically model these networks, calculate a yield of useful products, and pin point parts of the network that constrain the production of these products. Genetic engineering techniques can then be used to modify the network in order to relieve these constraints. Once again this modified network can be modeled to calculate the new product yield.

<span class="mw-page-title-main">Acetyl-CoA carboxylase</span> Enzyme that regulates the metabolism of fatty acids

Acetyl-CoA carboxylase (ACC) is a biotin-dependent enzyme that catalyzes the irreversible carboxylation of acetyl-CoA to produce malonyl-CoA through its two catalytic activities, biotin carboxylase (BC) and carboxyltransferase (CT). ACC is a multi-subunit enzyme in most prokaryotes and in the chloroplasts of most plants and algae, whereas it is a large, multi-domain enzyme in the cytoplasm of most eukaryotes. The most important function of ACC is to provide the malonyl-CoA substrate for the biosynthesis of fatty acids. The activity of ACC can be controlled at the transcriptional level as well as by small molecule modulators and covalent modification. The human genome contains the genes for two different ACCs—ACACA and ACACB.

In biochemistry, lipogenesis is the conversion of fatty acids and glycerol into fats, or a metabolic process through which acetyl-CoA is converted to triglyceride for storage in fat. Lipogenesis encompasses both fatty acid and triglyceride synthesis, with the latter being the process by which fatty acids are esterified to glycerol before being packaged into very-low-density lipoprotein (VLDL). Fatty acids are produced in the cytoplasm of cells by repeatedly adding two-carbon units to acetyl-CoA. Triacylglycerol synthesis, on the other hand, occurs in the endoplasmic reticulum membrane of cells by bonding three fatty acid molecules to a glycerol molecule. Both processes take place mainly in liver and adipose tissue. Nevertheless, it also occurs to some extent in other tissues such as the gut and kidney. A review on lipogenesis in the brain was published in 2008 by Lopez and Vidal-Puig. After being packaged into VLDL in the liver, the resulting lipoprotein is then secreted directly into the blood for delivery to peripheral tissues.

<span class="mw-page-title-main">Jay Keasling</span> American biologist

Jay D. Keasling is a professor of chemical engineering and bioengineering at the University of California, Berkeley. He is also associate laboratory director for biosciences at the Lawrence Berkeley National Laboratory and chief executive officer of the Joint BioEnergy Institute. He is considered one of the foremost authorities in synthetic biology, especially in the field of metabolic engineering.

<span class="mw-page-title-main">Butanol fuel</span> Fuel for internal combustion engines

Butanol may be used as a fuel in an internal combustion engine. It is more similar to gasoline than it is to ethanol. A C4-hydrocarbon, butanol is a drop-in fuel and thus works in vehicles designed for use with gasoline without modification. Both n-butanol and isobutanol have been studied as possible fuels. Both can be produced from biomass (as "biobutanol" ) as well as from fossil fuels (as "petrobutanol"). The chemical properties depend on the isomer (n-butanol or isobutanol), not on the production method.

<span class="mw-page-title-main">Biotechnology in pharmaceutical manufacturing</span>

Biotechnology is the use of living organisms to develop useful products. Biotechnology is often used in pharmaceutical manufacturing. Notable examples include the use of bacteria to produce things such as insulin or human growth hormone. Other examples include the use of transgenic pigs for the creation of hemoglobin in use of humans.

<span class="mw-page-title-main">Fatty acid synthase</span> Class of enzymes

Fatty acid synthase (FAS) is an enzyme that in humans is encoded by the FASN gene.

Acetyl-CoA synthetase (ACS) or Acetate—CoA ligase is an enzyme involved in metabolism of acetate. It is in the ligase class of enzymes, meaning that it catalyzes the formation of a new chemical bond between two large molecules.

<span class="mw-page-title-main">2,4 Dienoyl-CoA reductase</span> Class of enzymes

2,4 Dienoyl-CoA reductase also known as DECR1 is an enzyme which in humans is encoded by the DECR1 gene which resides on chromosome 8. This enzyme catalyzes the following reactions

<span class="mw-page-title-main">Stearoyl-CoA 9-desaturase</span> Class of enzymes

Stearoyl-CoA desaturase (Δ-9-desaturase) is an endoplasmic reticulum enzyme that catalyzes the rate-limiting step in the formation of monounsaturated fatty acids (MUFAs), specifically oleate and palmitoleate from stearoyl-CoA and palmitoyl-CoA. Oleate and palmitoleate are major components of membrane phospholipids, cholesterol esters and alkyl-diacylglycerol. In humans, the enzyme is encoded by the SCD gene.

In enzymology, a [acyl-carrier-protein] S-malonyltransferase is an enzyme that catalyzes the chemical reaction

In enzymology, a long-chain-alcohol O-fatty-acyltransferase is an enzyme that catalyzes the chemical reaction

The E-site is the third and final binding site for t-RNA in the ribosome during translation, a part of protein synthesis. The "E" stands for exit, and is accompanied by the P-site which is the second binding site, and the A-site (aminoacyl), which is the first binding site. It is involved in cellular processes.

<span class="mw-page-title-main">Jens Nielsen</span> Danish biologist

Jens Nielsen is the CEO of BioInnovation Institute, Copenhagen, Denmark, and professor of systems biology at Chalmers University of Technology, Gothenburg, Sweden. He is also an adjunct professor at the Technical University of Denmark. Nielsen is the most cited researcher in the field of metabolic engineering, and he is the founding president of the International Metabolic Engineering Society. He has additionally founded several biotech companies.

Pitrilysin is an enzyme. This enzyme catalyses the following chemical reaction:

Charles Clifton Richardson is an American biochemist and professor at Harvard University. Richardson received his undergraduate education at Duke University, where he majored in medicine. He received his M.D. at Duke Medical School in 1960. Richardson works as a professor at Harvard Medical School, and he served as editor/associate editor of the Annual Review of Biochemistry from 1972 to 2003. Richardson received the American Chemical Society Award in Biological Chemistry in 1968, as well as numerous other accolades.

<span class="mw-page-title-main">Cell engineering</span>

Cell engineering is the purposeful process of adding, deleting, or modifying genetic sequences in living cells to achieve biological engineering goals such as altering cell production, changing cell growth and proliferation requirements, adding or removing cell functions, and many more. Cell engineering often makes use of DNA technology to achieve these modifications as well as closely related tissue engineering methods. Cell engineering can be characterized as an intermediary level in the increasingly specific disciplines of biological engineering which includes organ engineering, tissue engineering, protein engineering, and genetic engineering.

References

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