Engineering Biofuels PDF

12.10 Engineering Biofuels Major current biofuels (biologically-produced fuels): Ethanol, biodiesel, hydrogen, methane In 2019, the global biofuels market amounted to over 136 billion U.S. dollars. Natural or engineered bacteria can participate in production of biofuels. Bacterial c...

12.10 Engineering Biofuels Major current biofuels (biologically-produced fuels): Ethanol, biodiesel, hydrogen, methane In 2019, the global biofuels market amounted to over 136 billion U.S. dollars. Natural or engineered bacteria can participate in production of biofuels. Bacterial conversion of switchgrass to ethanol More than 14 billion gallons of ethanol produced/year in the United States from fermentation of corn sugar by yeast (Figure 12.30a), but alternative nonedible plant materials are more desirable feedstocks.  Switchgrass (Panicum virgatum) requires significant pretreatment to be broken down to fermentable sugars. Caldicellulosiruptor is a gram-positive anaerobic thermophile that produces a cellulase and can bind switchgrass with tapirins. C. bescii has been engineered with enzymes from another thermophile, Clostridium thermocellum, to shift fermentation from mainly acidic products to 70 percent ethanol. Thermophile are advantageous because of reduced risk of mesophilic contamination, improved substrate solubility, easier collection of volatile products.  Engineered alkenes and alkanes Petroleum contains hydrocarbons of varying chain length, such as Propane (C3H8). Modified Escherichia coli converts glucose into propane and other petroleum hydrocarbons. begins with fatty aldehyde synthesis using heterologous expression of Photorhabdus luminescens luxCED genes that reduce fatty acids to aldehydes (Figure 12.31) Nostoc punctiforme aldehyde decarbonylase also cloned to convert fatty acids into hydrocarbons added enzymes from fatty acid elongation in Bacillus subtilis to generate higher-octane fuels  Microalgae and biodiesel microalgae: unicellular phototrophic eukaryotes that produce bioactive compounds including lipids, fatty acids, and carotenoids using sunlight, CO2, minerals, water examples: Chlorella and Chlamydomonas that produce triacylglycerides (TAG), or storage lipids that can be chemically treated to yield biodiesel Improving TAG synthesis required genetic engineering (e.g., vectors allowing proteins to target nucleus, chloroplast, mitochondrion, endoplasmic reticulum). (Figure 12.32a) 12.11 From Synthetic Metabolic Pathways to Synthetic Cells Synthetic biology: Using genetic engineering to create novel biological systems out of biobricks (promoters, enhancers, operators, riboswitches, regulatory proteins, enzyme domains, signal receivers) A high level bioengineering Make novel products and replace chemical synthesis example: International Genetically Engineered Machine (iGEM; http://igem.org) undergraduate competition  Engineering food product Vanillin Natura vanillin is a secondary metabolite extracted from seedpods (vanilla beans) of vanilla orchid. Vanilla farming is sustainable, labor-intensive and culturally important to families in the rain forests of Madagascar, Mexico and Southeast Asia. Vanillin is produced mainly by chemical synthesis from lignin or fossil hydrocarbons. https://keolamagazine.com/agriculture/hawaii-islands-vanilla-industry/  Vanillin biosynthesis Engineered E. coli and yeast can synthesize vanillin from glucose. In E. coli five heterologously expressed enzymes are required to make “synbio vanillin” Tyrosine overproduction Tyrosine to ferulic acid Ferulic acid to vanillin https://www.nature.com/articles/srep13670  Synthetic pharmaceuticals: Artemisinin and malaria pharmaceuticals often derived from natural products artemisinin: antimalarial drug naturally produced by sweet wormwood plant that cannot be economically synthesized Artemisia annua Artemisinin = Wiki https://www.nobelprize.org/prizes/medicine/2015/tu/lecture/  avermectin artemisinin “Discovery of Artemisinin - A Gift from Traditional Chinese Medicine to the World” - Tu Youyou, Nobel Lecture https://www.nobelprize.org/prizes/medicine/2015/tu/lecture/  33.5 Plasmodium and Malaria Malaria a protist disease caused by Plasmodium spp. estimates of 350 million people infected worldwide. Each year 1-3 million people die from malaria. generally found in tropical and subtropical regions Wiki Size 15-25µm Sporozoites, one of several different forms of the parasite, from a mosquito  Plasmodium infection cycle A complex life cycle that includes Anopheles mosquitoes as vectors (Figure 33.11) Fever, chills, headache, nausea, vomiting, muscle pain, fatigue. Figure 33.11  Diagnosis requires identifying Plasmodium-infected erythrocytes in blood smears. (Figure 33.12) Drugs are used to prevent and treat infections. Chloroquine Primaquine – inducing oxidative stress in red blood cells Gates Foundation’s effort on providing Bed-nets, treated with insecticides, to prevent Malaria may recur years after mosquitoes from biting people at night. the primary infection. Several vaccines are currently in development. can be controlled by draining swamps or eliminating mosquitoes or blocking vector transmission  Semi-Synthetic Artemisinin Project Engineer a microorganisms for the synthesis of artemisinic acid (and ultimately artemisinin, by chemical processing). (Figure 12.33) Saccharomyces cerevisiae (a yeast) strain designed that produces large amounts of artemisinic acid ∞ Figure 12.33  Photographic engineering of bacterial cells Engineered bacteria (E. coli) grown as a lawn on agar; unilluminated bacteria make dark pigment, illuminated bacteria do not. (Figure 12.34) requires three biobricks pathway (from cyanobateria) to convert heme into phycocyanobilin (light- harvesting pigment) and turns E coli to green. light detector and signaling module: photoreceptor-EnvZ -> OmpR -> transcription control of ompC promoter Control of -galactosidase which converts X-gal to make a darker color read more by yourself  Synthetic Cells “synthetic bacterium”: artificial construction of a bacterial genome inserted into a different species to yield viable cells (Figure 12.35) wo - t t