11 industrial microbiology.ppt

11 industrial microbiology.ppt - CEE 266 ENVIRONMENTAL...

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Unformatted text preview: CEE 266 ENVIRONMENTAL BIOTECHNOLOGY Lecture 11 (Microbial Fuels and Industrial Microbiology) Industrial Microbiology •  Microorganisms, typically grown on a large scale, are used to produce products or carry out chemical transformation •  Major organisms used are fungi and bacteria •  Classic methods are used to select for high-yielding microbial variants Figure 25.1 Primary and Secondary Metabolites Primary Metabolite   Produced during exponential growth, e.g., alcohols   Secondary Metabolite   Produced during stationary phase, e.g., antibiotics   Not essential for growth   Formation depends on growth conditions   Produced as a group of related compounds   Often significantly overproduced   Often produced by spore-forming microbes during sporulation Primary and Secondary Metabolite Production Formation of Alcohol by Yeast Figure 25.2a Penicilin Production by the Mold Penicillium Chrysogenum Figure 25.2b Antibiotics: Isolation and Characterization   Antibiotics   Compounds that kill or inhibit the growth of other microbes   Typically secondary metabolites   Most antibiotics in clinical use are produced by filamentous fungi or actinomycetes   Still discovered by a laboratory screening process   Microbes are obtained from nature in pure culture   Assayed for products that inhibit growth of test bacteria Microbially-produced Vitamins  Production of vitamins is second only to antibiotics in terms of total pharmaceutical sales   Vitamin B12 produced exclusively by microorganisms   Riboflavin can also be produced by microbes Microbially-produced Amino Acids and Enzymes   Amino acids used as feed additives and nutritional supplements   Glutamic acid (MSG)   Aspartic acid and phenylalanine (aspartame)   Bacterial amylase (starch-digesting) and proteases (protein-digesting) are used in laundry detergents   Cellulases used in fabric softeners   Amylases and glucoamylases produce high-fructose corn syrup   DNA polymerase in biotechnology and forensics (PCR) White Wine Production Red Wine Production Figure 25.18a,b The Chemistry of Vinegar Production Figure 25.22 Microbial Fuels   Energy sourced from photosynthetic microbes or waste/wastewater   Liquid Biofuels   Cellulosic & corn ethanol   Biodiesel   Gaseous Biofuels   Methane, Propane mix, etc.   Hydrogen   Biological electrical voltage Microbial Energy Production Microbial Fuel Cell Microbial Fuel Cells vs. Microbial Electrolysis Cells   MFC: oxygen consumed at the cathode; no hydrogen produced C2H4O2 + 2H2O 2CO2 + 8e- + 8H+ (Anode Potential = -300 mV) O2 + 4H+ + 4e- 2H2O (Cathode Potential = +200 mV (+800 mV theoretical))   Circuit Working Voltage = 200 - (-300) = 500 mV   MEC: No oxygen consumed; hydrogen produced at the cathode C2H4O2 + 2H2O 2CO2 + 8e- + 8H+ (Anode Potential = -300 mV) 8H+ + 8e- 4H2 (Cathode potential = 0mV)   Voltage needed to make H2 = 410 mV (theoretical). So, the circuit should be augmented with at least 110 mV Effect of Oxygen on Microbial Fuel Cells Anoxic (MEC) Aerobic (MFC)   Oxygen can kill or inhibit cell   Oxygen can act as electron growth   Usually heterotrophic because accepter and inhibit energy generation phototrophs generally produce   Must control O2 levels oxygen   Can be phototrophic,   Must inoculate with nutrients and control oxygen heterotrophic, or both   Much easier to scale up Microbial Fuel Cell Configurations Electron Transfer   Electron shuttles, e.g. methylene blue dye   Dyes can be taken in by cells   Pick up electrons; shuttle to electrode   Cells can make direct contact with electrodes   Cells lose electrons through membranes   Excess electrons are captured by electrode   Best with cells that form biofilms for maximum electron contact   Nanowires   Electron microscopic images show formation of wires by cells for shuttling electrons to each other/electrodes via nanowire contacts Challenges in Optimization of Fuel Cells   Biological   Bacterial metabolism   Bacterial electron transfer   Physical   Performance of the cation selective membrane   Intrinsic electrical resistance of the system   Biochemical   Efficiency of the cathode oxidation step Why Algae? •  Much greater productivity than terrestrial plants •  Non-food resource •  Use otherwise nonproductive land •  Can utilize saline water •  Can utilize waste CO2 streams from power plants or industries •  Can be used in conjunction with waste water treatment •  An algal biorefinery could produce oils, protein, and carbohydrates Algae Biofuels Portfolio Final Product Processes Uses Biodiesel Oil extraction and Transesterification Diesel combustion engines Ethanol Fermentation Internal combustion engines Methane Anaerobic digestion of biomass; Methanation of syngas Fuel; electricity production Hydrogen Triggering sulfate-deficient photosynthesis in algae; Processing of syngas Fuel; chemical and petroleum industries Heat & Electricity Direct combustion of algal biomass Direct heat and electrical applications Other Hydrocarbon Fuels Gasification/pyrolysis of biomass and processing of resulting syngas Most gasoline engines; feedstock to produce biodiesel Algae Cultivation   Grow selected algae   Collect syngases (e.g., hydrogen)   Harvest algal cells   Extract oil from cellular biomass   Transesterifiy SVO to produce biodiesel   Ferment remaining biomass for ethanol or digest for methane   Dewater and use solids for animal food and pet food   Extract and process protein for human supplements Transesterification for Biodiesel Production   Stepwise reaction converting triglycerides (from algae) to glycerol with methyl esters (biodiesel) as byproducts   Alkalis (such as sodium hydroxide) and alkoxides (such as sodium methoxide) used as catalysts Algae Cultivation Systems Open-pond systems   Unstirred ponds   Inclined ponds   Central pivot ponds Closed Photobioreactors  Continuously stirred reactors and bags  Tubular photobioreactors Open-pond Systems         Circular Ponds:   Has a rotating agitator attached to create flow   Oldest cultivation method Inclinded Ponds: Sloped pond bottom to create turbulent flow Areas not turbulent can be contaminated Photobioreactors Advantages   Less contamination   Limits loss of carbon dioxide   Easy to design   Artificial or real sunlight Continuously stirred reactor Disadvantages   More expensive than open ponds   Operating costs   Cleaning and sterilization costs Tubular Photobioreactor ...
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