Microbial Metabolism and Control Lecture Notes

Comprehensive vocabulary flashcards covering microbial metabolism, growth phases, and chemical/physical control methods based on lecture material.

Catabolic reaction

A process that breaks down organic compounds, releases energy in the form of $ATP$, is exergonic, and uses hydrolysis.

Anabolic reaction

A process that builds organic compounds, requires $ATP$, is endergonic, and uses dehydration synthesis.

Aerobic respiration summary equation

$$C_6H_{12}O_6 + 6O_2 + 36ADP + 36P \rightarrow 6CO_2 + 6H_2O + 36ATP$$

Glycolysis $ATP$ yield

$$2,ATP$$

Kreb's Cycle $ATP$ yield

$$2,ATP$$

ETS (Electron Transport System) $ATP$ yield

$$32,ATP$$

Entner-Doudoroff pathway

A metabolic pathway occurring only in Gram-negative bacteria that yields $1,ATP$.

Pentose Phosphate pathway

A metabolic pathway occurring in both Gram-positive and Gram-negative bacteria that yields $1,ATP$.

Lactic acid fermentation products

$$2,ATP + 2,\text{lactic acids}$$

Alcohol fermentation products

$$2,ATP + 2,\text{alcohols}$$

Purpose of photosynthesis

To produce glucose, which is subsequently used in aerobic respiration to make $ATP$.

Oxygenic photosynthetic bacteria

Cyanobacteria (formerly known as blue-green algae) which produce $O_2$.

Anoxygenic photosynthetic bacteria

Green and Purple Sulfur bacteria which do NOT produce $O_2$.

Binary fission

The process where one cell elongates, pinches, and divides into two identical daughter cells.

Generation time

The time required for one cell to divide into two; for E. coli, this is $20,\text{minutes}$ under ideal conditions.

Lag phase

A period of slow growth and metabolism where the bacteria are alive but not dividing rapidly; the patient is potentially infectious.

Log phase (exponential growth)

A period of rapid binary fission and high metabolism; it is the best time to administer antibiotics and the patient is highly infectious.

Stationary phase

The phase where the number of living cells is approximately equal to the number of dying cells due to food depletion or immune system/drug intervention.

Death phase

The phase where the number of dead cells exceeds the number of living cells, though the population never reaches $100\%$ dead.

Relapse

Occurs when a patient stops antibiotics too early, leading to a secondary log phase where the second antibiotic is often less effective.

Bactericide

An agent with a -cide suffix that kills bacteria.

Bacteriostatic

An agent with a -stat or -stasis suffix that inhibits bacterial growth or stops/steadies the population.

Sepsis

Indicates bacterial contamination; derived from the Greek for decay or putrid.

Asepsis

The condition of being free of contamination.

Sterilization

The total destruction of ALL microorganisms, including endospores.

Disinfection

The destruction of pathogenic vegetative bacteria, but not endospores.

Degermination

The mechanical removal of bacteria from a surface.

Sanitization

Lowering bacterial counts to meet health department guidelines.

Moist heat mechanism

Bactericidal method that denatures proteins; examples include autoclaving and pasteurization.

Autoclave

A moist heat sterilization method that kills all microorganisms, including endospores.

HTST Pasteurization

High-Temperature Short-Time: $72^\circ\text{C}$ for $15,\text{seconds}$; kills pathogens and lowers bacterial count.

Filtration

A method that removes but does not kill bacteria; uses $0.22,\mu\text{m}$ or $0.45,\mu\text{m}$ filters, or HEPA filters.

Desiccation

A bacteriostatic method involving the removal of water, such as freeze-drying (lyophilization).

Osmotic pressure

A bacteriostatic method where high salt or sugar concentrations cause bacterial desiccation.

Radiation mechanism

Bactericidal method that damages DNA; UV causes the formation of thymine dimers.

Iodine

A bactericidal antiseptic that denatures proteins; examples include Betadine and tincture of iodine.

Chlorine

A bactericidal disinfectant that denatures proteins; used in water purification and Clorox.

Sodium benzoate

A bactericidal food preservative used in sodas and snacks to prevent mold growth.

Sodium nitrite/nitrate

A bacteriostatic food preservative used in processed meats to prevent Clostridium germination; carries a carcinogenic risk.

Ethylene oxide

A bactericidal gaseous sterilant that binds to proteins, enzymes, and DNA; used for plastics and rubber.

Quaternary ammonium compounds

Surface-active agents that target plasma membranes; notably, some bacteria like Pseudomonas can grow in them.

HEPA filter

High-Efficiency Particulate Air filter; removes bacteria larger than $0.3,\mu\text{m}$.

Thymine dimers

DNA structural damage caused specifically by UV radiation.

Lyophilization

A form of freeze-drying (desiccation) used for preserving items like coffee, cereal, and jerky.

Ways Antimicrobials Kill Bacteria (5)

1. Inhibition of cell wall

2. Inhibit or damage DNA &/ or RNA

3. Inhibit protein synthesis (translation)

4. Attack the plasma membrane

5. Inhibit folic acid synthesis - stops DNA synthesis

Sulfur Dioxide

Bactericidal and denatures proteins

Gaseous Agents

Binds to proteins, enzymes, endospores, and DNA to destroy them (Ex. Ethylene Oxide)