Bacterial Culture, Growth, and Development; Environmental Influences Worksheet

BIO315, Week 7

Please compare and contrast archaea and bacteria.

archaea → ether links, isopropyl, exotic forms (when low pH, extreme temperatures), cell wall differences that make it similar to peptidoglycan, few plasmids (replicates independently), ascended genotypically, RNA polymerase similar to eukaryotic enzymes; ribosomes similar to eukaryotes and archaeal promoters similar to bacteria

bacteria → eukaryotes (have diglycerol), ester links, NAG and NAM, phospholipid bilayer (polysaccharidein middle and fatty acid tail in middle)

(homeostatic → cytoplasms get inverted in cold temperature to maintain fluidity in lipid monolayer membrane)(cold temp = short length and restricts movement; warm temp = long length with fatty acids)

What are the different ways that microbes can uptake nutrients.

active diffusion → low to high using ATP; symport and antiport

passive diffusion → along concentration gradient, no need for energy like ATP, high to low

facilitated diffusion → follow concentration gradient (high to low), cannot pass normally, needs escort to go in or out of cell like gases

transport system → glucose is phosphorylated into cell, occurs in membrane; for glycolysis, different concentration

electron transport → created symport and antiport, occurs specifically in regular membrane of cell (motor force)

symport → from same direction

antiport → opposing directions from each other

(proton motive force requires energy)

What part of innate immunity best combats bacterial siderophores?

fever → combats bacterial siderophores → needs iron → low concentration of it in unfavorable conditions (fever lowers iron concentration)

high fever → bacterial infection, low fever → viral infection (can differentiate through T cells and toll receptors, detection shows innate immune system working, occurs in both gram +- cytokines)

What does media need to include? What techniques can scientists use to count the number of bacteria in a culture?

media → needs to include electron source, energy source (if not phototrophic), carbon source (if not autotrophic), nitrogen source (if not N2 fixer), varies for different bacterial species

techniques: spectrophotometry, biomass (more biomass, more uphill density), live testing (will live and reproduce, live on through S-phase/mitosis)

What is happening at the different stages of the growth curve? How could you experimentally test if a culture is in the death phase?

lag phase → cells synthesizing materials but not dividing (no active growth)

log phase → exponential growth in bacteria; 1, 2, 4, 8, 16…; increases linearly

stationary phase → cells no longer growing and are at a stable still

death phase → decline in bacteria; microdeath = D interval, how long does it take for 90% of bacteria to be killed? at 99% = 2D interval

to test death phase → death rate>birth rate; in late stationary phase = death rate = birth rate; every time cell dies, nutrient drops and new cell takes nutrient to grow and birth; plate for cfu and use VBNC, live dead microscopy, or stain

Please compare and contrast continuous culture with synchronous culture.

continuous culture → cells are kept in a condition of continuous steady growth at a constant population size; outcome of nutrient limitation and balancing the rate of reproducing cells through growth to the rate of loss of cells through media removal; fresh media is added and older is removed; good for studying cell cycles and metabolic activity

synchronous culture → dynamic 2.5 hour cell cycle; easily synchronized; ubiquitous in fresh and salt water (tap); non-pathogenic gram-negative bacterium; heavy metal resistance and bioremediation

Please describe the process of sporulation and germination.

sporulation → producing spores under starvation stress (dormant); leads to septum in cytoplasm, dual compartments for mother to produce spore

germination → vegetative cell; peptidoglycan fragment detected and awakens

vegetative cell → sporulation (caused by stressors (starvation, toxins, heat)) → spore → germination with PG fragments → vegetative cell

Please demonstrate how exponential growth of a microbial culture and exponential death in response to antimicrobial agent both are logarithmic. This is a math-based question.

lag phase → cells synthesizing materials but not dividing (no active growth)

log phase → exponential growth in bacteria; 1, 2, 4, 8, 16…; increases linearly

stationary phase → cells no longer growing and are at a stable still

death phase → decline in bacteria; microdeath = D interval, how long does it take for 90% of bacteria to be killed? at 99% = 2D interval

Under what circumstances it is useful to use physical, chemical, or biological agents to control microbial growth?

physical → pasteurization, doesn’t kill all cells, leaves food; creamers, autoclaving (kills all bacteria under a certain temperature, for surgical instruments), radiation (UV, X-ray, gamma; mutations = death), filtration (no need to kill (for heat sensitive cultures; but viruses can pass through filtration)

chemical → disinfectants (kill all microbes, destroys eukaryotic cells as well (cannot be used inside patients), bleach, iodine), agents to remove microbes attached to surfaces (ex. soap and detergents), antibiotics (selectively kills microbes (may not work on all species), has minimal effect on eukaryotic cells and can be used inside patients, interferes with bacterial-specific enzymes (cell wall synthesis, bacterial ribosome)), penicillin (blocks cell wall synthesis, growing bacteria lyse (slow-growing bacteria take longer to die))

biological → probiotics (“good” bacteria, displace disease organisms from tissues), bacteriophages (for antibiotic resistant bacteria, do not harm eukaryotes)