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CHAPTER 1 - Microorganisms and Microbiology.docx

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Biology 2581B
Chris Brandl

MICROBIOLOGY CHAPTER 1: MICROORGANISMS AND MICROBIOLOGY 1.1 THE SCIENCE OF MICROBIOLOGY • Microbiology: study of microorganisms  understand microorganisms + apply understanding of microbial life • Microorganisms: single-celled microscopic organisms and include the viruses, which are microscopic but not cellular  Independent entities  carry out life processes independent of other cells  plants/animals are multicellular and can’t live alone (organs can’t live alone) • basic biological sciences: microbio uses and develops tools for probing the fundamental processes of life  all cells, micro or multicellular, are similar in some way  Microbial cells can be grown to high densities in small-scale lab cultures – easy for biochem and genetics study • applied biological sciences: microbio is important for human/vet medicine, agriculture and industry  can be good (increase soil fertility) or bad (cause diseases)  used to develop protein and antibiotics • collectively, micro-o constitue to bulk of biomass and is important for life • help recycle nutrients and degrade biomass • huge diversity – can live in extreme places (extreme pH, chem, temperature) 1.2 MICROBIAL CELLS • cell: fundamental unit of life; isolated from other entities by membrane/cell wall outside membrane Properties of Cellular Life • FIG 1.3 properties of cells (p. 4) • Metabolism: cells take in nutrients from env’t and transform them into new cell materials/waste products  E is conserved – helps build key structures  Formation of new cell = final result of metabolic activity • Growth: reproduction; increase in cell number from cell division • Evolution: process of descent with modification in which genetic variants are selected based on their reproductive fitness  Occurs faster when selective pressure is strong (ex. selection for antibiotic resistance in pathogenic bacteria) • Motility: cell’s ability to move away from danger/unfavourable conditions and to exploit new resources or opportunities (ex. flagella) MICROBIOLOGY • Differentiation: produce modified cells specialized for growth, dispersal or survival Cells as Biochemical Catalysts and as Genetic Entities • Activities of cells can be viewed as biochemical catalysts or genetic coding devices  Both support cell growth • Before cells divide, all constituents in cell double  Require enzymes (catalytic ability) to supply energy and precursors for biosynthesis of cell components  Genome, the entire complement of genes, also replicates 1.3 MICROORGANISMS AND THEIR ENVIRONMENT • Microbes live in populations; population = group of cells derived from single parental cell by cell division • Habitat: immediate env’t in which a microbial population lives • Resources and conditions (temp, pH, etc) in habitat control diversity and abundance • Microbial communities: populations of cells interacting with other populations • Interactions btw pop’n can be beneficial, harmful or neutral  Ex. waste from one pop can be food or poison to another pop • Ecosystem: all living organisms, physical and chemical components of environment  Can expand/contract depending on resources/conditions • Microbial ecology: how microorganisms affect plants, animals and whole global ecosystem 1.4 EVOLUTION AND THE EXTENT OF MICROBIAL LIFE • Micro-o were 1 entities on Earth w/ proper living systems • Cyanobacteria: phototrophic mo that produced oxygen as metabolic waste The First Cells and the Onset of Biological Evolution • Last universal common ancestor (LUCA): all cells are similar and descended from a common ancestral cell, known as LUCA • First cells arose from nonliving materials -> grew in population -> interact with other populations Life on Earth through the Ages • FIG 1.6 (p. 6) • First 2 billion years: Earth was anoxic; had N 2nd CO and2other gases  Anaerobic micro-o survived MICROBIOLOGY  Ex. Metanogens: micro-o that produced methane  Phototrophic mo (o that harvest E from light) appeared w/in a billion years of the formation of earth  Ex. purple bacteria • Increase in O d2e to cyanobacteria caused an eruption of multicellular life • LUCA – bacteria, archea, and eukarya (3 lineages of microbial cells)  Microbial eukarya were ancestors of plants/animals • Biomarkers: specific moleculres that are unique to particular groups in present- day mo; reveals whether specific group was present at a certain time The Extent of Microbial Life • Major fraction of biomass + reservoirs for nutrients • About 2.5x10 cells • Most do not live on Earth’s surface, but live up to 10km subsurface  Subsurface cells grow super slowly but contribute to diversity 1.5 THE IMPACT OF MICROORGANISMS ON HUMANS Microorganisms as Agents of Disease • FIG 1.8 • 100 yrs ago, main cause of death was pathogens: mo that cause infectious diseases (mostly in children and elders)  Improved sanitation, healthcare, understanding of diseases and antimicrobial agents (antibiotics) help decrease effect of pathogens • Mo can still be major threat....microbial diseases: malaria, TB, cholera, African sleeping sickness, etc.; also, diseases that emerge suddenly: bird/swine flu Microorganisms, Digestive Processes and Agriculture • Legumes have nitrogen-fixating bacteria called nodules on their roots, which convert N t2 NH , 3hich plants use for growth • Some bacteria also cycle sulfur: oxidize H S 2nto SO 42- • Rumen: bacteria found in digestive vessels of ruminant animals (ex. cows, sheep) used to digest and ferment cellulose at neutral pH • Humans: Mo populations occur only in the colon and cannot degrade cellulose; microbial flora can also be found in skin and oral cavities • Escherichia coli/salmonella are transmitted from infected meat/contaminated fruits and veggies and can cause diseases Microorganisms and Food, Energy, and the Environment • Mo can spoil food (huge economic loss) so people preserve food (can, freeze, dry) MICROBIOLOGY • Good mo: fermentation of cheese, yogurt, buttermilk, sauerkraut, pickles and sausages; baked goods and alcohol rely on fermentation of yeast • Mo can produce biofuels  Methane: produced from anaerobic degradation of organic matter by methanogenic mo  Ethanol: produced by fermentation of glucose from sugarcane/cornstarch; can be used as motor fuel  Waste materials (domestic refuse, cellulose, animal waste) can be converted into ethanol; better than using corn  Biodiesel from soybean • Microbial bioremediation: use MO to clean up human pollution  Introduce specific MO to polluted env’t  Add nutrients to stimulate pre-existing MO to degrade pollutants • Industrial microbiology: grow MO on a large scale to make produces of low commercial value (ex. antibiotics, chemicals, enzymes) • Biotechnology: use genetically engineered MO to make produces with high commercial value, such as human proteins  Genomics: science of the identification and analysis of genomes; greatly
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