Microbial Growth – Flashcards
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| What are the 4 chemical rxns that aid in microbial growth? |
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| energy transformations, synthesis of monomers, polymerization of macromolecules, formation of cellular structures |
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| What is binary fission |
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| starting with one cell that ends up into two daughter cells |
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| what are determinants of population growth? |
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| growth rate, generation, generation time, exponential growth |
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| Exponential growth |
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| phase of growth cycle where cells are moving at fastest growth |
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| Growth cycle of populations: lag phase characteristics (3) |
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| seen with old inoculations, damaged cells, transfer from nutrient rich to nutrient poor media |
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| Growth cycle of populations: exponential phase characteristics (3) |
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| cells in healthiest state, midexponential cells, rates of exponential growth can vary |
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| When does exponential growth tail off? |
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| stationary phase |
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| What growth phase are nutrients limited? |
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| stationary |
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| What growth phase is there a buildup of waste products? |
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| the stationary phase |
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| What growth phase do you have no net increase or decrease in cell number? |
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| stationary phase |
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| What growth phase do you have cryptic growth (and what is cryptic growth) |
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| birth rate=death rate, stationary phase |
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| What growth phase do you have sur genes? |
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| survival genes to conserve energy (stationary phase) |
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| What is the death phase? |
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| more death than life --> net decrease in cells |
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| What are the 4 phases growth curve? |
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| lag, exponential, stationary, death |
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| Which growth phase is the longest? |
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| death |
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| Which growth phase is the shortest? |
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| lag |
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| What are the three characteristics of direct microscopic count? |
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| - dry or liquid methods - counting chambers - quick |
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| What are the disadvantages of direct microscopic counting? 5 |
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| 1) cant distinguish dead from living 2) Small cells are difficult to see 3) precision is difficult to achieve 4) Phase contract for unstained specimens 5) not used with low density suspensions |
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| What is viable count? |
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| plate count or colony count |
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| What type of count assumes there is only one cell per colony? |
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| viable count |
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| What measurement of growth technique spreads cells across plate? |
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| viable count |
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| what measurement of growth uses the pour plate method (and what is it) |
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| viable count - it is having it on top of the agar plate |
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| what measurement of growth uses dilutions? |
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| viable count |
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| What are the sources of error in viable count? 3 |
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| 1) inoculum size, medium, and incubation conditions 2) Different growth rates 3) May underestimate numbers |
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| What are the advantages of viable count? |
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| 1) high sensitivity 2) select for different population |
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| Measurement of growth: turbidometric methods: what does it measure? |
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| turbidity caused by a cell suspension (turbidity is proportion to cells present) |
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| Measurement of growth: turbidometric methods. What does a photometer measure? |
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| Klett units *um what |
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| Measurement of growth: turbidometric methods - what does a spectrophotometer measure? |
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| optical density |
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| Measurement of growth: turbidometric methods - what does it measure |
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| unscattered light |
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| Define turbidity |
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| proportional to cell numbers |
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| What type of measurement growth must you prepare a standard curve? |
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| turbidometric methods |
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| what happens in a turbidity measurement? |
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| scattering of light |
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| how is the bug in a continuous culture? |
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| it stays in a steady state |
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| Continuous culture: batch culture |
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| fixed volume of medium |
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| Continuous culture |
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| flow system |
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| continuous culture: steady state |
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| constant cell number and nutrient status |
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| continuous culture: chemostat |
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| dilution rate, limiting nutrient |
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| TF: in a chemostat, you will have cultures in 'stationary' all the time |
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| T |
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| Effect of environment on growth: temp; what are the three cardinal temperatures? |
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| minimum, optimum, maximum |
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| Temp classes: phychrophile |
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| 4 degrees: polaromonas vacuolaa |
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| Temp classes: mesophile |
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| 39; escherichia coli |
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| Temp classes: thermophile |
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| 60; bacillus stearo-thermophilus |
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| Temp classes: hyperthermophile ( lower level ) |
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| 88: thermococcus celer |
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| Temp classes: hyperthermophile ( higher level ) |
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| 106: pyrolobus fumarii |
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| What temp class is archea? |
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| hyperthermophile |
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| TF bacteria is more acid tolerant than bacteria |
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| False, fungi is more acid tolerant |
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| What kind of bacteria are acidophiles? |
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| acidophilic bacteria |
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| In an acidophile, what do membranes depend on? |
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| low ph |
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| picrophilus oshimae optimum for pH and temp |
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| .7 and 60 degrees |
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| Where do you find alkaliphiles |
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| soda lakes and carbonate soils |
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| what supplies energy for transport and motility in an alkaliphile? |
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| sodium gradient |
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| what is the internal pH of an organism, no matter what |
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| neutral with relatively narrow range |
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| What is plasmolysis |
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| cytoplasm shrinks away from cell wall |
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| What do halophiles require? |
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| NaCl |
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| Osmophiles like |
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| high sugar |
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| xerophiles like |
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| very dry environments, they need to be able to rip nutrients from the H2O |
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| What do aerobes tolerate? |
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| full O2 tensions |
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| What is Microaerophiles relationship with O2 |
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| (require O2 but does not need all O2) |
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| what is microaerophiles tolerance for o2? |
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| less than 21% |
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| what microorganism has a limited capacity for respiration? |
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| microaerophiles |
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| What is an aerotolerant anaerobe? |
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| it is not killed by o2 but it wont grow in O2 |
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| What is an obligate anaerobe? |
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| Lives in the absence of air |
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| What is a facultative anaerobe? |
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| makes ATP using aerobic respiration if air is present, if not it switches to fermentation |
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| What is required for aerobes? |
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| aeration |
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| What require exclusion of O2 |
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| anaerobes |
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| 4 points under "anaerobes require exclusion of O2" |
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| - fill medium container completely - reducing agent - anerobe jar - anaerobic glove boxes |
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| Test tubes: what does an obligate anaerobe look like? |
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| concentration at the bottom |
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| Test tubes: what does facultative look like? |
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| dense concentration at top and sporatically spread throughout |
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| Test tubes: micro aerophile |
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| density right at top |
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| Test tubes: aero tolerant |
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| spread evenly throughout |
