microbio midterm (ch7 and 8)

• - No increase in cells
• - May grow in size
• - Period of unbalanced growth
• - Proteins necessary for the uptake of available nutrients may be synthesized
• - A period of adjustment; no cell division occurs.

• - Cells are in balanced growth
• - Each cell in the population doubles within an essentially identical unit 
• - Important factor in rapid food spoilage on the onset of an infectious disease
• - General time in time for doubling if the # of cells is constant.

• - Cells continue to metabolize slowly.
• - Some cells die and lyse when energy is exhausted.
• - Period of survival and may mimic the condition in nature.
• - Reproduction of cell death are exactly the same.

• - When culture is maintained in stationary phase beyond a certain length of time.
• - When death phase exceeds the rate of reproduction.

• N_o - Initial amount of bacteria.
• t - Amount of time it was growing.
• N_t - Amount of bacteria present at t.
• n - Amount of generations.
• generation time = time/generation

• n = (logN_t - logN_o)/log2 
• N_t = N_{o *} 2ⁿ

• A= log(I_o/I)
• High absorbance readings are no longer proportional to mass because no enough light is being transmitted enough to get an accurate measurement.

• A culture of organism where every cell in the same stage of division.
• It is used to research bacterial cell division. It is difficult to study the cell division from one specific cell so can a synchronous culture will work. The events at the molecular level pertaining to protein synthesis, polymerization reactions, and subsequent cell assembly reactions. The sequence of events during a cell cycle can be quantitated with reasonable accuracy only when we examine a population in which all of the cells are at the same stage of division.

Higher y_max  (g of cell/ mol glucose) and y_atp (g of cell/ mol ATP) is more efficient.

If nutrient level is adequate.

Batch culture -a nutrient liquid medium is prepared in an Erlenmeyer flask, sterilized, inoculated. The inoculated flask is then placed on a shaker (if aerobic) at appropriate growth temperature for a suitable growth period.

• Dilution rate (D)
• Volume (v)
• Flow rate (f) - v/t
• D= f/v

When the substrate level does not exceed the requirements for maintenance energy.

• Bacteria that favors bellow 20 ^oC.

Bacteria that favors between 20 ^oC - 44 ^oC

Bacteria that favors 45 ^oC - 70 ^oC.

Bacteria that favors 70 ^oC to higher than 110 ^oC

Microbes found in freshwater that can not tolerate moderates amount of salt.

Bacteria that can adapt to fresh wash and moderate amounts of salt (less than .75M NaCl )

Bacteria that is lives at pH 5 or below.

Bacterial that lives at pH 5.1 - 8.9.

Bacterial that lives at pH 9-11.

Only grows in the presence if molecular oxygen. It has no mechanism for energy generation other than a respiratory pathway that is geared to O₂ as terminal electron acceptor.

Follows a respiratory pathway when oxygen is available, but it can employ alternate anaerobic energy-generating systems when oxygen is not available.

Organisms that occupy niches where the atmosphere has limited levels of oxygen.

Cannot grow in the presence of oxygen.

Thrives at high pressure.

• Osmolarity of .9% saline.
• MW of Na = 23 g/mol
• MW of Cl = 35.5 g/mol
• .9gNaCl x 1 mol NaCl x 100ml
• 100ml        58.5 g          L        = .16 M NaCl

• .16 M NaCl x 2 = .32 Osm
• .32(4) = 1.28 Osm

• Conditions - Under pressure 15 Psi, 121.6 ^oC
• - In an auotoclave, pV = nRT so P keeps H2O from boiling off.

• Conditions- 160 - 180C in oven for 2-4 hours.
• - Glassware, pippettes in cannisters wrapped in foil, protect from contamination. (Endospre contamination)

• Conditions: 63 - 66 C 30 min, or 71.6 C 15s
• - For mil/beer, doesn't sterilize.

• Condition: High in Gamma rays.
• - Destructive to genetic material, free radicals (OH*) Resistance varies between species.

• Condition: Blast of ray between 220 and 320 nm.
• - Thymine dimers, but microbes have repair mech. Must: UV damage > repair.

• Usually room temp and pressure conditions.
• - Glass fiber depth filters, membrane filters isospore membrane filter. The size of the spores can vary depending on the size of the bacteria.

Array of chemical agents that are used in the control of undesirable organisms. The agent will eliminate a pest without doing significant harm to other species.

They are more selective in that they target a specific process of the bacteria. They can gain resistances to them.

Involves all microbes.

Inhibitory

Dissolving

Can destroy microorganisms on contact but causes harm to host tissue.

Kills or prevents growth without causing harm to host tissue.

A chemical compound that can be applied topically, taken orally, or injected that will inhibit or kill microbes that cause infection.

Minimum inhibitory concentration - The lowest concentration that will inhibit growth.