Main Concepts

Question 1

Ubiquity of microorganisms:

Answer 1

Broth
Agar
TSY plates
Know how to swab

Question 2

Microscope:

Answer 2

Whatever magnification on lens, times ten for eye lens.
10x objects: see 25 micrometer size (Protozoa) 20-100
40x objective: see 6 micrometer size (yeast) 4-10
100x objective: see 2.5 micrometer (bacteria) 1
Virus 0.1 micrometer, too small for microscope.

Question 3

Microscopy wet mounts:

Answer 3

Brownian motion: random vibration movement
Motility: organism swimming using flagella usually.

Question 4

Aseptic technique:

Answer 4

Be sterile

Question 5

Microscopy: simple staining/ gram stain

Answer 5

Purpose of oil immersion: prevent refraction of light. Allows good resolution (able to see closely spaced objects as indidiviual objects)
Gram stain is differential stain.

Question 6

Plate counts:

Answer 6

Confluent growth: lawn of cells: not isolated colonies.
CFU: not all organisms will grow in lab setting.

Question 7

Isolating and identifying bacteria

Answer 7

Tests

Question 8

Aerobic vs anaerobic growth

Answer 8

Microaerophiles: organism require oxygen but can only tolerate it in limited amounts)
Aerotolerant anaerobes: grow in presence of oxygen but don’t use it for metabolism.

Question 9

Killing bacteria by moist heat:

Answer 9

Endoscopes are bacillus and clostridium.

Question 10

Uv bacteria

Answer 10

Kills bacteria through DNA mutation. Does not effect endoscopes.

Question 11

Isolation of streptococcus salivarius.

Answer 11

TSY+ sucrose make S. Salivarius gumdrop like.

Question 12

Generation time

Answer 12

Lag, log/expoential, stationary (new cells = dying cells), death phase (out of resources!)
Higher temp= faster generation time

Question 13

Isolation and examination of microorganisms in soil

Answer 13

Nitrogen fixations: Azotobacter, clostridium, Klebsiella.
Endoscopes very resistant to regular gram stain. (Appear colorless)
Endospore stain:
Make green paper towel stain over sample and heat over a boiling water bath for 10 minutes.
Rinse briefly with water and allow to decolorize by flooding slide WITH water for a few seconds.
Counterstain with Saffranin.

Question 14

Antibiotic production by streptomyces.

Answer 14

Narrow spectrum antibiotics: inhibit of kill only limited types of microorganisms,
Broad spectrum: inhibit or kill wide range of microorganisms

Question 15

Luminescent bacteria

Answer 15

Bacterial luciferase: produces light through this enzyme.

Question 16

DNA-mediated transformation:

Answer 16

Conjugation: sex
Transduction: bepacterial DNA introduced by bacteriophage.
Transformation: DNA taken from environment.
Acinetobacter is gran nagtive molitke bacteria. Naturally competent: capable of transformation at all stages of growth.
Bacillus! Competent from log phase to stationary ohase.
E. Coli never been competent unless in lab.
Prototrophs: capable of synthesizing all of the organic metabolites required for growth.
Auxotrophs: lacks, the ability to synthesize one or more essential metabolites.
Growth in quadrant 1 means didn’t lyse cell enough.
TSY allow any organism to grow, so only DNA won’t grow on it cause it ain’t alive,
Acinetobacterium doesn’t supply Trp, and only Trp- that uptakes DNA from lyse cell will grow, and of course Trp+ will grow fine cause it already has it. DNase will kill DNA in that quadrant,

Question 17

Water analysis.

Answer 17

Indicator organism
Coliforms: gram negative rods that ferment lactose with production of A/G within 48 hours, Enterobacter(lighter, dark center, no green sheen on EMB ) and Klebsiella.
Ex. E.coli: always present in feces, slight green sheen in EMB agar.
MPN test: most probable number test: statistical estimate of cell number in which multiple samples of the water sources are incoculated into a lactose broth to be tested.
EMB agar plate:
Selective: dyes inhibit gram positive growth and gram negative cocci.
Differential: lactose fermenting = pink/purple, non fermenting is colorless.

Question 18

Virus: tittering

Answer 18

Individual phage= virion
Lambda= bacteriophage type
Plaques: place phage has infected cell and killed it
Titer: concentration of bacteriophages. (Isolated plaques are result of infection of a single cell by a single virion, # of plaques = # of phage particles added to lawn of cells.
Pfu not cfu!!

Question 19

Agrobacterium

Answer 19

Opines amino acid derivatives only able to be used by bacterium itself.
Ti (plasmid that induces tumor)

Question 20

Urine species UNKOWN:

Answer 20

MacConkey agar: differential medium: contains lactose and pH indicator: lactose fermenting turn reddish purple, non-lactose fermenting remain colorless.
Selective: only gram negative rods live!
Blood agar:
Differential: hemolysis, not selective.