MICROBIOLOGY BILL SOEFFING LAB PRACTICAL COMPILATION- updated

If the soil sample was desiccated, the bacteria which would most likely survive are the _____, primarily due to their ability to form spores.

a) streptococci

b) member is of the genus bacillus

c) enteric forms like E. coli

d) gram-positive rods

e) gram positive cocci

B

ellipsoidal bacteria are called

a) spirilla

b) bacilli

c) vibrios

d) spirochetes

e) cocci

cocci

Which of the following is a differential medium?

a) nutrient broth

b) nutrient agar

c) phenol red agar

d) all the above

e) none

phenol red agar

If a nutrient tall was "seeded" when the agar was still too warm (65 degrees c) the most likely type of bacteria to grow would be:

a) psychrophiles

b) mesophiles

c) thermophiles

d) tow of the above

e) all the above

thermophiles

Bacteria are commonly supported by hypotonic solutions. The osmotic gradient and the cell wall are significant in maintaining the cellular morphology.

a) true

b) false

true

Name the four characteristics used to describe colony morphology. (CEPS)

color, edges(shape), profile(texture), surface (elevation)

Four reagents are used when doing a gram stain. Each of the reagents have a specific purpose. Match the reagent with the appropriate purpose.

gram crystal violet - primary stain

gram's iodine - mordant

acetone alcohol - decolorizer

safranin - counterstain

The exoenzyme produced by bacillus subtilis for the hydrolysis of starch is:

amylase

In anaerobic conditions, the end products of respiration are pyruvate (organic acid) and nitrite ion, fermentation (alcohol), and water. (True/False)

False- Alcohol & CO2 and Lactic Acid

Digestion of milk protein is called peptonization and results in the release of ammonia, which will cause an alkaline condition

false (lactation not peptonization)

Which of the following substances is not a source of carbon?

ammonium salt

Generation time refers to:

The time required for a cell to divide and the population to numerically double

When an organic compound serves as a final hydrogen acceptor, the process is called:

fermentation

Indicate which of the following are exoenzymes or end-enzymes:

amylase - exoenzyme

gelatins - exoenzyme

What are the four chemicals used in the Gram staining procedure?

safranin, crystal violet, iodine, alcohol

pH indicator, to form dark purple at low pH

Inhibit the growth of Gram-positive (selective- selects only for gram neg. but also diff for gram neg. bacteria)

Contains the carbohydrate lactose, which allows differentiation of gram-negative bacteria based on their ability to ferment lactose.

isolates fecal coliforms

Eosin Methylene Blue Agar

To test if the bacteria have the capability to grow under specific conditions. Neither selective or differential.

nutrient agar

tests for Gram-negative vs Gram-positive

Gram positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls

Gram negative bacteria stain red, which is attributed to a thinner peptidoglycan wall

Gram's Staining Method

Selective for halophilic organisms (or salt-loving bacteria)

A. faecalis=NOT a halophile.

S. epidermidis, S. aureus (simulants), P. vulgaris=halo-tolerant

Sodium Chloride Agar

Measurement of bacterial growth in solutions pH differences and dextrose levels

McFarland scale

Differential

Test if the bacteria is acidic (yellow) or alkaline (red), the ability to ferment sugar

Also test if iron sulfide present (Hydrogen Gas)--black residue would be present

TSI agar

differential= bacteria's ability to produce exoenzyme amylase because starch is too big to enter through cell wall

- flood with iodine which will turn blue, purple, or black in the presence of starch

- halo indicates that the bacteria has already hydrolyzed (breakdown) the starch

Starch Agar

Lactose fermentation (without gas)Pink, acid

reduction of litmus white, any pH, white starts at bottom (pink and rigid curd)

rennet curd

purple/violet- alkaline (no acid production), no reduction of color, no separation, rennett curd

pink- acidic, lactose fermentation

white- reduced, turned clear

rennett curd- peptonization

gas- visible bubbles

Litmus Milk

selective (inhibits growth of bacteria that don't love salt) & differential (what can/can't ferment mannitol)

pH indicator- acidic (change phenol red to yellow= can ferment mannitol) & basic (stays red= can't ferment mannitol)

most pathogenicity oraganisms with ferment, isolates pathogenic staph

halophilic and yellow is fastest & most pathogenic

Mannitol Salt Agar

differential

-yellow and bubble of gas= acidic (carbohydrate catabolism)

-fuschia, no bubble = basic (protein catabolism), no rxn

-proteins = gas

-aerobic-bubbles at top

-anaerobic-bubbles at bottom

-facultative-bubbles throughout

ferm tubes

Test if the bacteria is acidic or alkaline based on metabolic waste products

-fuchsia (protein catabolism) = basic (alkaline)

-yellow(carbohydrate catabolism) = acidic

phenol red agar

Gram-positive bacteria (purple)

B. subtilis

S. aureus (simulans)

S. epidermidis

Gram-negative bacteria (red)

A. faecalis

E. aerogenes

P. vulgaris

E. coli

S. marcescens

Bacteria are commonly supported by hypotonic solutions. The osmotic gradient and the cell wall are significant in maintaining the cellular morphology. (true/false)

true

Transamination of one amino acid liberates the amino group for incorporation into another molecule that become a peptide and allows the deaminated portion of the first amino acid to enter the Kreb's Cycle Linkage as pyruvate. (true/false)

true

Cyanide is a strong inhibitor or iron-containing enzymes because it binds with iron and deprives the enzyme of its cofactor. Which of the following would be subject to this noncompetitive inhibition?

a. oxidative phosphorylation

b. reverse electron flow system used by chemoautotrophs

c. non-cyclic photophosphorylation

d. two above

e. all above

all above

Essay: Explain how multiple metabolic pathways may have arisen that have similar reactants and/or products. (type lol to proceed)

lol (This answer mostly deals with the reasoning that you start with the same products and similar reactants you can have diffferent cycles because of the variety that you add in the different processes. idk.)

Bacilli/rod + Flagella

single

gram negative

Stays Phenol Red: produces ammonium hydroxide, alkaline conditions because CANT metabolize (ferment) dextrose carbohydrate

NOT a halophile

Alcaligenes faecalis

Bacilli/rod + Flagella

single/staphlo/strepto

gram positive

Starch: produces amylase enzyme to break down dextrose polymers and create a halo

Deep Butt: yellow anaerobic metabolism of glucose. lactose metabolized aerobically.

CANT ferment lactose=no curdtolerant of heat

Bacillus subtilis

Bacilli/rod +flagella single

gram negative

Entire, smooth, buttery, milky white, raised profile.

outnumber serrate marcescens colonies

Anaerobic

glucose fermenters

Enterobacter aerogenes

bacilli/rod

single

gram negative

Starch: no halo. CANT metabolism carbs

Ferments Lactose: large acid curd formation from production of casein. White deposit means litmus was reduced.

NOT tolerant of heat exposure. Eosin Methylene blue dye: black/purple color change=fecal chloriform

Escherichia coli

cocci

staphylo

gram positive

halophilic

Mannitol 7% agar: turns yellow first so is more pathogenic

Staphylococcus (simulans) aureus

gram negative

bacilli (rod)

entire edge, smooth, buttery, red, convex/raised profile.

succumbed to enterobacter aerogenes growth. Bacilli/rod

single

facultative anaerobic rod

Serratia marcescens

cocci

staphlo

gram positive

phenol red: metabolizes carbohydrates

halophile

less pathogenic (later color change) than staph simulans

Staphylococcus epidermidis

petri dishes are aerobic or anaerobic?

aerobic

gram negative, rod shaped

can ferment sugar

halotolerant

thrives, "swarming growth" on NaCl agar

Proteus vulgaris

fermentation tubes aerobic or anaerobic?

anaerobic

TSI tubes - aerobic vs anaerobic

bottom/butt anaerobic

top/slant is aerobic

If you have a fermentation tube with fuchsia color, what catabolized to give that reaction?

protein

What is the bubble in a Durham tube?

CO2 or hydrogen

What are the end products of aerobic carbohydrate metabolism?

CO2, water, ATP

Phenol red dextrose plate makes acid and turns yellow?

CO2 combines with water to make carbonic acid to change indicator color.

If the fermentation tube turns yellow and the carbohydrate fermentation end products could be CO2 (gas bubble/organic acid), what else is a product at the end?

alcohol

In aerobic conditions, respiration end products are water and carbon dioxide. (true/false)

true