Class Note for MIC 205A at UA
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Date Created: 02/06/15
Microbial Growth Growth of Microbes Increase in number of cells not cell size One cell becomes colony of millions of cells Growth of Microbes Control of growth is important for infection control growth of industrial and biotech organisms Factors Regulating Growth Nutrients Environmental conditions temperature pH osmotic pressure Generation time Chemical Requirements 1 water Elements C 50 of cell s dry weight HONPS Trace elements Organic Source of energy glucose Vitamins coenzymes Some amino acids purines and pyrimidines Nutritional Categories Carbon sources CO2 autotroph organic heterotroph Energy sources sunlight phototroph organic chemotroph Nutritional Categories Saprobe lives on organic matter of dead organisms Parasite lives on organic matter of living host pathogens Cowlm m n MvXSlAlaHlll Zulu ulna ire nemesis unwind in lnpludmlan m l away Membrane Fig 73 Movement of Water Osmosis Hyperlonic Cells with lsoronic Hypclcnlc Cell Wall l l l cell wall l l Water concentration is equal inside and Mel dlflusicrl ol waiei is inlo me call his Wale dilluses our oi lne cell and cuisine lne cell mus rates oi dirrusien swells me prolopiesl and pushes liligmly shrinks me protoplasl away irem are equal In both diremmns againsl lne wall Wall usually prevents me cell wall process is known as cell lrom bursting plasmolysis Cells Lacking Cell Wall Early Early Cell membrane Laie Dilluslun all water Intu quot12 Cell Causes Water amusing out oi the Cell Causes Rates ei ulnueiun are equal ii to shrink and become distorted in both directions it to swell and may burst it i no mechanism exists to remove lhe waleri r a 7 Dlreciion oi nel walermovemenl Facilitated diffusion higher to lower concentration carrier molecule eminent new immerse re Mm mm c quotparameters Outside inside Outside Inside cell cell cell cell Active transport lower to higher takes energy camiignm Tie Ne ialell Emlpamuar in renewquot Timur lei epidemicquot a new Membrane Membrane Membrane 5 3 r K 2531 K I o Extracellular lniiacellular Extracellular lrlraceliular Extracellular inlracellular a L b Group translocation lower to higher with chemical change Copynglll e The Mc mw Hlll Cumpallles Inc Oeimlami required lei rupmduuiiun or dluplay Membrane Membrane Extracellular Intracellular Bulk transport endocytosis phagocytosis pinocytosis icrovi l Liquid enclosed by microvllli x ro e 2Vesicle with liquid Environmental Factors Influencing Growth Temperature 02 pH Osmotic Pressure Others radiation atmospheric pressure Temperature Optima Psychrophiles coldloving Mesophiles moderate temperature loving Thermophiles heatloving Each has a minimum optimum and maximum growth temperature Rate of Growth Psychrophlle l Mesophile Opt39mum Thermophlle l f i l Minim L39lIf 1 Maximum l 1 I l l I l l I 15105 O 51015202530354045505560657075808590 Temperature 0C Temperature Optima Optimum growth temperature is usually near the top of the growth range Death above the maximum temp comes enzyme inactivation Mesophiles most common group of organisms 40 F 5 C slows or stops growth of most microbes r f 1 I Gram rod Microbe of the Day Listeria 1 r V monocytogenes n is Common In 39 xm environment 39 Lives in I monocytes W30 05 Listeria monocytogenes Listeria monocytogenes A Intracellular Psychrotroph Can move Listeriosis fever 7 hams through cell aches GI or CNS membrane to Symptoms 5122 spread from cell 39 Pregnant women to cell k suffer file cheese 7 ham sausages miscarriage Listeria monocytogenes Oxygen Requ39rements Listeriosis Obligate aerobes require 02 2500 casesyr W mm Facultative anaerobes can use 500 fatal m 02 but also grow without it Prevention meats Obligate anaerobes die in the Pasteurization presence of O2 Avoidance sh cheese ham Sausages Oxygen Tolerance Aerotolerant do not use 02 but can grow when it is present Often ferment glucose to lactic acid Microaerophiles require 02 but grow only in concentrations lower than air Toxic Forms of Oxygen Toxic Forms of Oxygen Singlet ogtqgen OZ very reactive Peroxide anions OZ2 Superoxide free radicals 0239 HZO2 broken down by catalase Neutralized by superoxide and perox39gase dismutase SOD Hydroxyl radical OH39 very reactive Brewer s Jar Lockscrew Catalyst chamber contains Omar I39d Inner I39d palladium pellets which 1 I scavenge excess oxygen Rubber gasket PrOVides provides airtight seal low OZ Gas generator envelope Water is hlg h 002 added to chemicals in envelope to Twas Will generate H2 and 002 H2 combines quotqu39d quot95393 with oxygen in chamber to produce H20 which is visible as condensation on the walls of the chamber Petri dishes Candle Pelri plates with solid media inverted Anaerobic indicator strip Methylene blue becomes colorless cw in absence of 02 b pH pH Most bacteria grow between pH 65 and 75 Many bacteria and Acid below pH 4 good viruses survive low pH preservative for pickles sauerkraut of stomach to infect cheeses intestines Acidophiles can live at low pH Helicobacter pylori lives in stomach under mucus layer Osmotic Pressure Bacteria 8090 water High salt in surrounding environment leads to water loss and plasmolysis Cell s plasma membrane shrinks cell growth inhibited Ecological Associations Symbiotic close nutritional relationship Mutualism both bene t Commensalism commensal bene ts host not harmed Parasitism parasite benefits host harmed Bacterial Division Bacteria divide by binary ssion Alternative means Budding Conidiospores lamentous bacteria Fragmentation Drying and High Osmolarity Salted sh jerky honey sweetened condensed milk are preserved by pulling water out of bacteria Hypotonic medium low osmolarity may lyse bacteria without cell walls Measuring Bacterial Growth duplicated chromosome becomes amxed lo a spacial membrane sue cl The septum wail grows inward a pulled m Theseviumiss nlhesized completely mug me ceii semen and the cell membrane waives useii so mat there are we sepevaie ceii chambers tel A lms pew me daughter cells are m 5 species will while others wi i remain attached immg chains m cnnblels luv example E Celiwall oeiimemmane o Chromosomet 397 Chromosome 2 Ribosomes Generation Time Time required for cell to dividefor population to double Average for bacteria is 13 hours E coi generation time 20 min 20 generations 7 hours 1 cell becomes 1 million cells WWW m Mbmwllili mwanwslit m m m in o WWW it liiiiiiiiilil Numbe 1 2 4 a 16 32 of cells Number of generations 1 2 3 4 5 Exponential 2 22 23 24 25 value l2x1 l2x2l 2x2x2 a annyilele mqu quotmoume im WWW un m Npmduuionvvcuplny 10 9 8 i 7 Lo of r E 5i i i gt 4 3 2 0 b Time gt hequot 039 Viable Cells Bacterial Growth Curve siaimnary phase 2 a 7 I I 5 a some cells remain viable Phases of Growth Lag phase making new enzymes in response to new medium Log phase exponential growth Desired for production of products Most sensitive to drugs and radiation during this period Phases of Growth Stationary phase nutrients becoming limiting or waste products becoming toxic death rate division rate Death phase death exceeds division Flask inoculated N am taken at many spaced imam Measuring Growth l l l l l l i l l Direct methods count individual ll It I I I ll ill H J Indirect Methods measure effects i ll 1 p l of bacterial growth medium 3 l l I l 1 it i c i j j i Plates are u a w l a 0 u V a b a a i a coCIUDiatEd39 None l U l V 1 i 1 39 I are counted 77 39 3 colonies CPU lt1 1 3 7 13 23 45 so 135 230 per 01 ml Total estimated cell population lt5000 5000 15000 35000 65000 115000 225000 400000 675000 1150000 h in flask 39 only 39 cells are present tn hp nqqav d Fig 717 Fig 716 Copynght le 1 r 39 39 Copynghl 6i Percent ol light transmitted lb Metabolic Activity stained water drop brewex s ye ast c arb ohydrate s Figure 18 Apparatus for mea surmg the production of carbon dioxide during fennentation
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