BIOL 2460 - EXAM 3 REVIEW - PARKS - MICROBIOLOGY

Binary Fission Steps

Binary Fission Steps

G - growth and increase in cell size R - replication of DNA D - cytoplasmic division; cytokinesis S - septum formation and daughter cell divisions

Z-ring

formed during cytokinesis with the FtsZ protein to form a divisome

Divisome

promotes the formation of peptidoglycan and septum

Generation Time

time takes to double population

E. coli

20 min.

S. aureus

30 min.

B. subtilis

120 min.

M. tuberculosis

15-20hrs

Nn

number of cells at generation n

n

number of generations

N0

initial number of cells

Growth curve

closed system with finite nutrients

Lag Phase

cells grow larger and metabotically active (inoculum cells)

Log Phase

exponential; binary fission; cell replication > cell death

Stationary Phase

cells enter survival mode and < less susceptible to antibiotics; cell replication = cell death

Death Phase

cell replication < cell death; endospores; persisters

Persisters

surviving cells with slow metabolism (tuberculosis)

Sustainable Growth

Open system cultures have infinite resources

Chemostat

used to maintain a continuous culture in which nutrients are supplied at a steady rate

Direct microscopic cc

cells are counted under a microscope; CANNOT distinguish between live or dead cells; Known volume is transferred to a calibrated slide (Petroff-Hausser chamber) and cells are manually counted

Fluorescence Staining

cells are counted under a microscope or flow cytometer; Red stain binds to damaged cells to indicate DEAD cells

Coulter counter

detects electrical resistance change due to cell density; CANNOT differentiate live/dead

Viable plate counts

count of live cells; samples are diluted and grown on solid media;

Pour Plate Method

bacterial sample mixed with warm agar - > sample poured onto sterile plate -> sample swirled to mix, allowed to solidify -> plate incubated until bacterial colonies grow

Spread Plate Method

sample poured onto solid medium -> spread sample evenly over the surface -> plate incubated until bacterial colonies grow on the surface of the medium

Optical Density (turbidity)

Measured w/ spectrophotometer; light is passed through culture and is measured on other side

Alternate Patterns of Growth

fragmentation in cyanobacteria and budding in planctomycetes: Gemmata obscuriglobus

Biofilm Formation

1. Attachment of planktonic cells to a substrate

2. Attachment becomes irreversible; cells become sessile

3. Growth & division on substrate

4. Production of extracellular polymeric substance (EPS)

5. Attachment of secondary colonizers & dispersion of microbes to new locations

Extracellular polymeric substances (EPS)

Hydrated polysaccharide gel with other macromolecules and channels (sugar-gel) EX: (rivers, pipelines, oral cavity) (cuts and wounds, lungs, intestines)

Quorum Sensing

cell to cell communication

Autoinducer

small molecules are produced to induce various actions (positive-feedback)

Biofilm and Human Health

1. Cells in deep layers may be metabolically inactive

2. EPS may slow diffusion of biocidal agents

3. Provide optimal environment for sharing of plasmids

Optimal oxygen concentration

ideal concentration of O2 (best for growth)

Minimum permissive oxygen concentration

lowest O2 concentration allowing growth

Maximum permissive oxygen concentration

highest O2 concentration allowing growth

Obligate aerobes

must have O2; Micrococcus luteus

Obligate anaerobes

prefers other than O2; Bacteroides spp.

Facultative anaerobes

can do both; Staphylococcus spp.

Aerotolerant anaerobes

tolerant to O2; Lactobacillus spp.

Microaerophiles

minimum O2; Campylobacter spp.

Fluid Thioglycolate Medium (FTM)

low % agar tube that has a gradient of O2

Aerotolerance

determined by location of growth

pH

acidic

Neutrophiles

~7 pH

Acidophiles

<5.5 pH

Alkaphiles

8-10.5 pH

Psychrophiles

<0°C; love cold and unsaturated

Psychotrophs

4-20°C; make food go bad

Mesophiles

20-45°C; human microbe

Thermophiles

50-80°C; love heat, saturated

Hyperthermophiles

80-110°C; some survive @ > 121°C

Halophiles

Salt/solute lovers

Halotolerance

tolerate high salt (MSA & S. aureus)

Barometric pressure

ability to withstand great pressure; extremophiles

Barophiles

require high atmospheric pressure; unculturable; hyper or thermophiles (found on bottom of ocean)

Photoautotrophs

cyanobacteria and green sulfurs

Photoheterotrophs

purple non-sulfurs

Enriched media

Extra care of nutrients to grow certain micro and are hard to grow

Fastidious

organisms cannot make certain (exact) nutrients and hard to grow

Chemically defined medium

complete chemical composition known

Complex medium

contains extracts and digests of yeasts, meat, or plants; exact composition not known

Selective media

inhibit unwanted, promote growth of organism of interest

Enrichment cultures

promote growth of desired organism; only represents a fraction present

Differential media

distinguish colonies of bacteria by color change

Sterilization

fomite; removal/killing of ALL microbes; methods: (autoclave) Heat, Pressure, Filtration, and Chemical (sterilants); endospores and viruses

Sanitization

fomite; reduce microbial load; heat or chemicals

Disinfection

fomite; Inactivation/kill of microbes; vinegar and bleach; ≠ sterile

Antisepsis

living tissue; hydrogen peroxide, iodine, witch hazel, rubbing alcohol

Degerming

living tissue; washing hands, wiping with paper towel, etc.; soap and alcohol swab

BSL-1

sink for hand washing and door to close off lab; nonpathogenic E. coli and B. subtilis

BSL-2

UTA micro lab; BSL-1, PPE, self-closing door, eye-wash station, autoclave, or sterilizationS. aureus and Salmonella spp.; viruses: hepatitis, mumps, and measles

BSL-3

BSL-1 and 2; respirator, bio safety cabinets, hands-free wash sink, 2 sets of doors, directional air flow; indigenous or "exotic" pathogens; M. tuberculosis and B. anthracis; viruses: west nile virus and HIV

BSL-4

+BSL-3; full biohazard suit, change clothing on entry, shower on exit, decontaminate all material on exit, lab must have own air supply; "exotic" pathogens; viruses:

Critical

must be sterile; items used inside body; sterile tissue or bloodstream; surgical instruments, catheters, IV fluids

Semicritical

do not require high-level sterilization (membranous tissue, GI endoscope, RT equipment

Noncritical

do not require sterilization; stethoscope, bed linens, BP cuffs)

Decimal Reduction Time (DRT)

how much time it takes to kill 90% (1 log reduction) of population

Dry Heat

incineration; direct application of high heat (>250°C); Bunsen burner and bacteria incinerator

Moist Heat

penetrates cells with high temp in liquid/vapor; autoclave

autoclave

raise temp of water increasing boiling temp (~121°C) by raising pressure to 15 psi (endospores and thermophiles)

Pasteurization

"flash" heating foods to kill most microbes

HTST

milk heated at 72°C for 15sec, then bottled and refrigerated

UHT

milk heated at 138°C for 2 or more secs, then sealed in airtight containers for up to 90 days w/out refrigeration

milkborne organisms killed by pasteurization

C. jejune, Coxiella burnetii, Listeria monocytogenes, E. coli 0157:H7, M. tuberculosis, M. paratuberculosis, Salmonella spp. and Yevsinia enterocolitica

Refrigeration and Freezing

-static

Pascalization

high pressure used in food industry to kill microbes and prevent endospore formation (botulism)

Desiccation

drying or dehydration; to preserve foods by removing water

Lyophilization

freeze drying; rapid freezing then placed under vacuum

ionizing radiation

enters into cells and disrupts molecular structures such as DNA (x-rays and gamma rays)

non-ionizing radiation

doesn't penetrate glass, plastics, etc. can damage cells w/ direct exposure (UV irradiation)

sonication

High frequency sound waves to disrupt cell structure

filtration

use of barrier to physically separate microbes

membrane filtration

removes microbes from liquid samples

Phenolics

Denature proteins & membranes; triclosan(banned by FDA), lysol, and carbolic acid

Heavy Metals

binds inhibits proteins; MSCsZ

HM: Mercury

treated syphilis but banned due to neural toxicity

HM: Silver

used today to treat burn wounds, pediatric ophthalmic nenatorum, and in antibiotics

HM: Copper Sulfate

used as algicide to treat pools

HM: Zinc

mouthwashes, calamine lotion, baby powder, argyria

H: Iodine

oxidizes cellular components; commonly used as a iodophor (complex with organic molecule)