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43 Cards in this Set

  • Front
  • Back
What is the the killing or removal of all living organisms? When is this process important (3 areas)?

Preparing media (after adding water), medical protocols, food systems
What method is used to kill vegetative cells and spores?

What two places is it performed?

What are the specific settings?

performed in an autoclave or in fermentors

121° C, for 15 minutes with 15 lbs/in2.
Describe the process of tyndallization
The solution is heated to 100° C for 30 min in the presence of flowing steam for 3 successive days.

After each heat cycle the material is incubated at 37° C until the next for the grow out of endospores, going from initial to final material
Pasteurization kills most BLANK and BLANK BLANK but not all bacteria.

It kills many things in milk; name 1 of the 4.
pathogens; spoilage organisms

Mycobacterium tuberculosis (TB), Brucella abortus, Salmonella, and Lactococci in milk.
Is pasteurization sterile?

What are the two methods of pasteurization?

1. LTH, low temp hold: 62.8° C for 30 min.
2. HTST, high temp short term: 71.7° C for 15 seconds (used for food)
What is a bacterial killing method that uses a membrane with a certain pore size, 0.22 milli microns?

Where is this method used?

What are some downsides?
Filtration method

Used bacteria, certain chemicals, amino acids, certain drugs

Can't filter viruses and is very slow
What is a bacterial killing method that uses filters to remove particles 0.3 milli microns or bigger?

Where is it used? WHEN is it used?
HEPA filtration

Used in hoods; used when working with tissue culture
What is a bacterial killing method that uses gamma rays from cobalt 60?

What is it used on?
Ionizing radiation

Used with foods and medical equipment
What is a bacterial killing method that uses UV rads at 260nm and causes T-T dimers?

What is a downside to this method?
Nonionizing radiation

Bacteria can easily fix the bulge in DNA caused by UV light
What are chemicals that inhibit or destroy microbial growth?

What are three specific chemicals? Describe them.
Antimicrobial Agents

Cidal agents, kill the organism.
Static agents, reversibly inhibit growth of the organism.
Lytic agents, cidal agents that destroy the microbe by cell lysis.
What are chemical compounds that destroy disease causing microbes and their products on inanimate objects?

What are less toxic and usually inhibit but do not always kill microbes?

What is the measurement of the germicidal action of a chemical (disinfectant) and comparing it to phenol called?
Phenol coefficient
Common Disinfectants and Antiseptics

What is a 5 % solution effectively kills all vegetative bacteria and many spores through leakage of cell contents?

Where is it used nowadays?

DNA isolation
Common Disinfectants and Antiseptics

What is a lipid solvent that kill cells by disrupting the lipids in the cell membrane?
Common Disinfectants and Antiseptics

What are cleaners that disrupt cell membranes commonly called? Name specific examples

Ex: soaps, emulsifiers, detergents and cleansing agents
Common Disinfectants and Antiseptics

What are strong oxidizers react with proteins, enzymes? How many PPM need for disinfection, and surfaces?
Halogens: chlorine, fluorine, bromine and iodine

0.5-1.0 ppm for disinfection, 200 ppm better for surfaces
Common Disinfectants and Antiseptics

What is iodophor? What two places is it used?
detergent + iodine

used in fermentation; industrial cleaner
Common Disinfectants and Antiseptics

What is triclosan? What are three places it is used?
An antibacterial

Used in Dawn dish soap, chemicals in the food industry, and toothpaste to destory gingivitis
Common Disinfectants and Antiseptics

What are substances that attach methyl or ethyl groups to proteins and DNA and results in death of the microbe?

Name specific examples (3)
Alkylating agents

Ex: formaldehyde, glutaraldehyde, ethylene oxide
Common Disinfectants and Antiseptics

What are substances that are toxic to microbes because they bind to sulfhydryl groups of proteins? Name specific examples (3)
Heavy metals

Ex: Mercury, copper sulfate (on plants), and silver nitrate (eye drops in infants)
Who termed the phrase antibiotic? What did he discover?

What does an antibiotic show?
Waksman; Discovered streptomycin

Zone of inhibition
Who brought about penicillin? What is the yield today?

from 1mg/L to 50g/L
How many antibiotics today? How many currently in production? How many are related structurally to penicillin?


How much and how long does it take to develop an antibiotic?
$300 million and 10-12 years
What makes a good antibiotic?
Selective toxicity that inhibits and/or kills the microbe and not damage the host.
How is an antibiotic developed?

What are two specific methods?
Isolate bacteria and fungi from soil/water samples that inhibit test organisms like E. coli; extract the genes for production and resistance.

1. combinatorial chemistry: start with spore structure and add groups
2. rational drug design: start with crystal structure of target molecule and design and synthesize chemical that will impact it (ex: some antivirals)
What are the four areas where antimicrobials work?
1. inhibition of cell wall synthesis
2. damage the cell membrane
3. inhibition of protein and nucleic acid synthesis
4. inhibition of cell metabolism
What are the structures common to penicillin G and V?

What destroys penicillin? What is resistant to this?
B-lactam ring and thiazolidine ring; synthethic ex: ampicillian

B-lactamase from resistant bacteria

Cephalosporins have a β lactam structure that is resistant to β lactamases.
How does penicillin inhibit bacterial cell wall biosynthesis?
inhibition of the transpeptidation step in peptidoglycan synthesis.
What are three antibiotics that damage the plasma membrane in bacteria?
Inhibitors of protein and nucleic acid synthesis

What impairs prokaryotic ribosome function, by interacting with the 30s ribosome, causing misreading of mRNA? Name 3 examples

Ex: streptomycin (Sm), kanamycin, neomycin
What does streptomycin specificially do?
Sm impacts the 30s ribosome; inhibits initiation and codon recognition in protein synthesis
Inhibitors of protein and nucleic acid synthesis

What interferes with the attachment of the aminoacyl tRNA to the ribosome and also interferes with codon recognition?
Tetracycline (Tc)
Inhibitors of protein and nucleic acid synthesis

What binds to the 23S rRNA on the 50S ribosomal subunit, inhibits peptide bond formation?
Inhibitors of protein and nucleic acid synthesis

What binds to the 50S ribosomal subunit that blocks peptide bond formation? (This is a macrolide antibiotic, lactone ring attached to a sugar.)
Inhibitors of protein and nucleic acid synthesis

What inhibit bacterial DNA dependent RNA polymerases?
What are structural analogs? Name an example
Items that compete with cellular metabolites in reactions

Ex: Sulfonamides are similar to PABA (precursor of folic acid) and therefore blocks vitamin synthesis.
Today, 2 to 3 antibiotics are need to kill bacterial infections. What are two examples of such bacteria?
MRSA (Methicillin-resistant Staphylococcus aureus) and VISA (vanocomycin insensitive S. aureus)
What are the two methods of antimicrobial testing?
Tube dilution and disk diffusion method aka Kirby Bauer
How does tube dilution work?
Tube dilution involves broth tubes with different conc of antibiotic, checking for growth or no growth
How does Kirby Bauer disk diffusion work?

Nowadays, it occurs in a...
In KB, antibiotic placed on a plate. Bacteria grows right up to the disk (resistance), or a zone of inhibition (sensistivity)

What two systems help maintain a continuous culture? Why is a continuous system economical?
chemostat: growth controlled by the flow rate of the system, via fresh nutrients

The product is collected continuously

turbidostat: device measures the turbidity of the growing cultures and adds fresh nutrients
What is it called when all populations are growing in the same phase or stage of growth on a growth curve?
synchronous cultures