Microbio 310 1st Edition Lecture 17 Outline of Last Lecture I. 13.1 PhotosynthesisII. 13.2 Chlorophylls and BacteriochlorophyllsIII. 13.3 Carotenoids and PhycobilinsIV. 13.4 Anoxygenic PhotosynthesisV. 13.5 Oxygenic PhotosynthesisVI. 13.6 The Energetics of ChemolithotrophyVII. 13.7 Hydrogen OxidationVIII. 13.9 Iron OxidationOutline of Current Lecture I. 13.10 Nitrification II. 13.11 AnammoxIII. 13.12 The Calvin CycleIV. 13.13 Other Autotrophic Pathways in PhototrophsV. 13.14 Nitrogenase and Nitrogen FixationVI. 13.15 Genetics and Regulation of Nitrogen FixationVII. 15.1 Industrial Products and the Microorganisms That Make ThemVIII. 15.2 Production and ScaleIX. 15.3 Antiobiotics: Isolation, Yield, and PurificationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.X. 15.4 Industrial Production of Penicillins and TetracyclinesXI. 15.5 Vitamins and Amino AcidsCurrent Lecture13.10 Nitrification• NH3 and NO2- (energy sources) are oxidized by nitrifying bacteria during the process of nitrification• Two groups of bacteria work in concert to fully oxidize ammonia to nitrate• Key enzymes are ammonia monooxygenase, hydroxylamine oxidoreductase, and nitrite oxidoreductase• Only small energy yields from this reaction – Growth of nitrifying bacteria is very slow• Ammonia-oxidizing bacteria – NH3 is oxidized by ammonia monooxygenase producing NH2OH and H2O– Hydroxylamine oxidoreductase then oxidizes NH2OH to NO2 (generates electrons and H+)– Electrons and protons used to generate ATP• Nitrite-oxidizing bacteria – Nitrite (NO2) is oxidized by enzyme nitrite oxidoreductase to nitrate (NO3)– Electrons and protons used to generate ATP13.11 Anammox• Anammox: anoxic ammonia oxidation– Performed by unusual group of obligate aerobes– Anammoxosome is compartment (specialized organelle) where anammox reactions occur • Protects cell from reactions occurring during anammox (has dense membrane)• Hydrazine is a volatile intermediate of anammox• Anammox is very beneficial in the treatment of sewage and wastewater (occurs at sewage treatment plants)13.12 The Calvin Cycle• The Calvin cycle– Named for its discoverer Melvin Calvin– Fixes CO2 into cellular material for autotrophic growth– Requires:o NADPH o ATP o ribulose bisphophate carboxylase (RubisCO)-catalyzses the first stepo phosphoribulokinase– 6 molecules of CO2 are required to make 1 molecule of glucose13.13 Other Autotrophic Pathways in Phototrophs• Green sulfur bacteria use the reverse citric acid cycle to fix CO2 • Green nonsulfur bacteria use the hydroxypropionate pathway to fix CO213.14 Nitrogenase and Nitrogen Fixation• Only certain prokaryotes can fix nitrogen• Some nitrogen fixers are free-living and others are symbiotic• Reaction is catalyzed by nitrogenase – Sensitive to the presence of oxygen• A wide variety of nitrogenases use different metal cofactors• Electron Flow in Nitrogen Fixation– Electron donor -> dinitrogenase reductase -> dinitrogenase -> N2– Ammonia (NH3) is the final product13.15 Genetics and Regulation of Nitrogen Fixation• Highly regulated process because it is such an energy- demanding process (bacteria don’t havetime to waste energy)• nif regulon coordinates regulation of genes essential to nitrogen fixation• Oxygen and ammonia are the two main regulatory effectors15.1 Industrial Products and the Microorganisms That Make Them• Industrial microbiology– Uses microorganisms, typically grown on a large scale, to produce products or carry out chemical transformation– Originated with alcoholic fermentation processes• Later on, processes such as production of pharmaceuticals, food additives, enzymes, and chemicals were developed– Major organisms used are fungi and Streptomyces (bacteria)– Classic methods are used to select for high-yielding microbial variants/mutant strainso Goal is to increase the yield of the product to the point of being economically profitable • Properties of a useful industrial microbe include:– Produces spores or can be easily inoculated– Grows rapidly on a large scale in inexpensive medium– Produces desired product quickly– Should not be pathogenic– Amenable to genetic manipulation* (need to be able to manipulate it)– *Mutation or transformation• Microbial products of industrial interest include: – Microbial cells– Enzymes– Antibiotics, steroids, alkaloids– Food additives– Commodity chemicals• Inexpensive chemicals produced in bulk• Include ethanol, citric acid, and many others15.2 Production and Scale• Primary VS secondary metabolites• Secondary metabolites (Penicillin)– Form near end of growth, frequently at/near/in stationary phase of growth– 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• Fermentor (cylindrical vessel) is where the microbiology process takes place; any large-scale reaction is referred to as a fermentation– Most are aerobic processes• Fermentors vary in size from 5 to 500,000 liters– Aerobic and anaerobic fermentors• Industrial Fermentors– Closely monitored during production run– Growth and product formation must be measured– Environmental factors must be controlled and altered as needed• Including temperature, pH, cell mass, nutrients, and product concentration– Data on the process must be obtained in real time15.3 Antibiotics: Isolation, Yield, and Purification• 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 laboratory screening • Microbes are obtained from nature in pure culture • Assayed for products that inhibit growth of test bacteria• Cross-streak method – Used to test new microbial isolates for antibiotic production– Streak an antibiotic-producing organism across part of an agar plate. Incubate and letorganism grow. Streak bacteria perpendicular to the antibiotic-producing organism. Incubate again to let test bacteria grow. The failure of several bacteria species to grow near the antibiotic-producing organism indicates that this organism produced an antibiotic active against