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Prokaryotic Growth Kathy Huschle Northland Community & Technical College

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Prokaryotic Growth Kathy Huschle Northland Community & Technical College Slide 2 Pure Cultures pure culture: population of organisms descended from one organism only approximately 1% of all bacteria can be cultured successfully in the lab Vibro chlorae Slide 3 Pure Culture colony, clone begins with a single bacterial cell placed on a solid medium such as agar agar provides specific nutrition for bacteria and a medium to grow on Nutritional Agar Colonies on agar Slide 4 Binary Fission method of bacterial reproduction cell divides exactly in half single cell division reproduction of the entire organism Slide 5 Binary Fission asexual no genetic recombination the DNA molecule replicates itself when bacterial reproduction takes place E. coli undergoing cell division Slide 6 Bacterial Growth bacterial growth = bacterial cell reproduction the process of binary fission doubles the population each time binary fission takes place this doubling time demonstrates exponential growth each generation results in a doubling of the population generation time is = to doubling time measure of microbial growth rate Slide 7 Bacterial Growth Curve: laboratory conditions bacterial growth generally follows a characteristic pattern 5 phases normal growth curve, with optimum environmental and nutritional conditions Slide 8 Bacterial Growth Curve: laboratory conditions lag phase no increase in cell numbers cells are adapting to the environment cells are preparing for reproduction synthesizing new DNA, etc. Slide 9 Bacterial Growth Curve: laboratory conditions log phase exponential phase maximal rate for reproduction this happens with a specific set of growth conditions those resources for growth are abundantly available Slide 10 Bacterial Growth Curve: laboratory conditions stationary growth phase maximum population for the resources available required nutrients become depleted inhibitory end products from cell metabolism accumulate cell growth = cell death Slide 11 Bacterial Growth Curve: laboratory conditions death phase cell death > new cell formation Slide 12 Bacterial Growth Curve: laboratory conditions phase of prolonged decline can last from months to years survival of the fittest Slide 13 Solid Media on solid media cells do not disperse readily nutrients become limited in center death phase occurs in the center with exponential phase at periphery of the bacterial colony Slide 14 Bacterial Growth most lab organisms are grown in a batch culture closed system new materials are not added waste products are not removed under these conditions bacteria populations follow distinct patterns of growth Algae batch cultures Slide 15 Bacterial Growth continuous culture maintained nutrients must be continually supplied end products must be removed exponential growth phase maintained Continuous culture in lab Slide 16 Natural Chemostat chemostat continuous culture device A cow, with its four stomachs, is natures perfect chemostat; constantly grazing to add nutrients and continually belching and other such mechanics to remove bacterial metabolic end products Slide 17 Environmental Parameters: influencing bacterial growth not all bacteria favor the same environmental conditions the effects of varying conditions are seen as differences in reproduction (bacterial growth) some environmental conditions that can affect bacterial growth include temperature oxygen salinity pH Slide 18 Environmental Influencing Factors: temperature temperature ideal temperature for growth varies between organisms specified by the bacterial genome Slide 19 Environmental Influencing Factors: temperature temperature growth range minimum to maximum temperatures for bacterial growth optimal growth temperature temperature at which the highest rate of reproduction occurs Slide 20 Environmental Influencing Factors: temperature 5 divisions of prokaryotes, based on optimal growth temperature psychrophiles psychrotrophs mesophiles thermophiles hyperthemophiles Psychrophile: Desulfofaba gelida Thermophile: Pyrococcus sp. Hyperthermophile: Thermococcus barophilus Slide 21 Environmental Influencing Factors: temperature psychrophiles optimum growth temperature: - 5 0 C 15 0 C found in the Arctic and Antarctic regions of the world Bacteria found in melt from a Russian outpost on Lake Vostok Desulfofrigus oceanense Slide 22 Environmental Influencing Factors: temperature psychotrophs optimum growth temperature: 20 0 C 30 0 C will grow at lower temperatures most commonly found in refrigerated food spoilage Stemphlium sarcinaeforme Slide 23 Environmental Influencing Factors: temperature mesophiles optimum growth temperature: 25 0 C 45 0 C most human pathogens are mesophiles adapted well to growth in the human body, whose normal temperature is around 37 0 C Salmonella Slide 24 Environmental Influencing Factors: temperature thermophiles optimum temperature: 45 0 C 70 0 C commonly found in compost heaps and hot springs, water heaters Sulfur pots in Yellowstone Sulfolobus Thermophile in a hot spring Slide 25 Environmental Influencing Factors: temperature hyperthermophiles optimum growth temperature: 70 0 C 110 0 C usually member of the Archae domain found in hydrothermal vents in the depths of the ocean Deep Sea Vent Slide 26 Temperature Ranges psychrophiles -5 0 C to 15 0 C psychotrophs 20 0 C to 30 0 C mesophiles 25 0 C to 45 0 C thermophile 45 0 C to 70 0 C hyperthermophiles 70 0 C to 110 0 C Slide 27 Temperature Considerations food preservation refrigeration inhibits fast growing mesophiles psychrophiles can still grow in refrigeration, but at a diminished rate freezing destroys microorganisms that require water to grow Slide 28 Temperature Considerations disease body temperature varies: extremities are usually cooler than 37 0 C some microorganisms can cause disease in certain body parts but not in others due to variations in body temperatures Slide 29 Environmental Influencing Factors: oxygen oxygen levels vary between environments and within the same environment based on O 2 requirements, prokaryotes are separated into the following groups obligate aerobes obligate anaerobes facultative anaerobes microaerophiles aerotolerant anaerobes Slide 30 Environmental Influencing Factors: oxygen obligate aerobes need oxygen present to multiply Giardia Slide 31 Environmental Influencing Factors: oxygen obligate anaerobes cannot multiply in the presence of oxygen often killed by traces of oxygen in their environment C. perfringens Slide 32 Environmental Influencing Factors: oxygen facultative anaerobes grow best with oxygen, but can grow without oxygen respiration if oxygen is available fermentation if no oxygen is present growth is greater in the presence of oxygen due to the production of more ATP (energy source of the cell) Aeromonas hydrophilia on intestinal cells Slide 33 Environmental Influencing Factors: oxygen microaerophiles require oxygen but have maximal growth at reduced oxygen concentration high concentration of oxygen inhibit growth Helicobacter sp. Slide 34 Environmental Influencing Factors: oxygen aerotolerant anaerobes indifferent to oxygen S. mutans Slide 35 Environmental Influencing Factors: pH based on pH of the environment, microorganisms are separated into the following groups neutrophiles acidophiles alkalophiles Slide 36 Environmental Influencing Factors: pH neutrophiles optimum pH of 7 (neutral) most microorganisms grow best between pH of 5 (acidic) and pH of 8 (alkaline) acidophiles optimal growth, pH of less than 5.5 alkalophiles optimum pH of 8.5 or greater Copper Copper tolerant acidophile Urinary bacterial infection caused by alkaline urine Slide 37 Environmental Influencing Factors: salinity H 2 O is required by all microorganisms for growth in some places H 2 O is hard to come by such as in salt concentrations if a cell is in an environment that has a greater solute concentration than the interior of the cell, then by osmosis the water will leave the cell causing plasmolysis (shrinking of the cell) Slide 38 Environmental Influencing Factors: salinity halophiles are microorganisms that have adapted to this kind of environment halophiles require high levels of sodium chloride moderate halophiles 3% salt concentration extreme halophiles: Archaea require at least 9% salt solution found in the Dead Sea Dunaliella salina cell, near a salt crystal. 40X Dead Sea Slide 39 Nutritional Influencing Factors major elements C, O, H, N, S, P, K, MG, Ca Fe essential components of protein, carbohydrates, lipids and nucleic acid needed to synthesize cell components Slide 40 Nutritional/Energy Influencing Factors heterotrophs utilize organic carbon autotroph utilize inorganic carbon phototrophs harvest the energy of sunlight chemotroph obtain energy by metabolizing chemical compounds Dinoflagellates Myxobacteria Purple Sulfur Bacteria: a chemotroph Slide 41 Nutritional Diversity prokaryotes are able to use diverse sources of carbon (an essential element) and energy this ability allows them to thrive in virtually and environment Forms of Carbon Slide 42 Nutritional Diversity photoautotrophs utilize the energy of sunlight obtain carbon from CO 2 primary producers of the microbial world 6CO 2 + 12H 2 O C 6 H 12 O 6 + 6H 2 O + 6O 2 photoheterotrophs utilize the energy of sunlight obtain carbon from organic compounds Cyanobacteria Rhodobacter sphaeroides Slide 43 Nutritional Diversity chemolithoautotrophs AKA as chemoautotrophs or chemolithotrophs energy from inorganic compounds such as hydrogen sulfide carbon from CO 2 Thiobacillus denitrificans Slide 44 Nutritional Diversity chemoorganoheterotrophs AKA chemoheterotrophs or chemoorganotrophs utilize organic compounds for energy and as a carbon source most common group of microorganisms associated with humans and animals important organic degraders B. vietnamiensis Brachionus calyciflorus Slide 45 Prokaryotes in the Lab studying microorganisms in their envi

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