Microbiology Lab 2 Practical Review

Enzymes convert _______ to _________

Substrates, end-products

A microbe can only metabolize substances that ...

It's genes encode

What is needed for metabolic reactions to occur

Enzymes

How can we detect the presence of enzymes

By measuring the decrease in concentration and the increase of a specific end product

A reactant is also known as a ________.

substrate

If an enzyme is produced, what will happen to the reactant

It will decrease e

The main goal of exoenzymes

Break down large substances into smaller substances to be imported into the cell

The main goal of endoenzymes

Acts on substances transported into the cell—> carbolic enzymes

Amylase breaks down

starch into glucose monomers

The start hydrolysis assay is designed to detect

Amylases

caseinase breaks down

casein

Why do we add iodine for a starch hydrolysis

Iodine forms a complex with starch to produce colored complexes

If starch is NOT present what will the streak on the plate look like

There will be a yellow-ish hue... did produce amylase

Is starch is present the streak will form

A dark complex... did not produce amylase

What are proteases

enzymes that break down proteins

Casein hydrolysis assay tests for

The ability of cells to produce exoenzymes called proteases

Caseinase breaks ____ to _____

Casein to short peptides and amino acids

positive casein hydrolysis test

zone of clearing in milk agar

Negative Casein Hydrolysis Test

no change in agar

Fermentation products include

Acid and Gas

Positive Carbohydrate Fermentation

yellow

Negative Carbohydrate Fermentation

red

Acid is detected by

A pH indicator, phenol red

Gas is detected by

durham tubes

What two things are requires for lysine decarboxylase to be produced

Anaerobic (no O2) and acid present

What are decarboxylases?

Enzymes that remove carboxyl groups from amino acids

Positive Lysine Decarboxylase test

DC w/o lysine yellow

DC with lysine purple

Four classes for temperature and bacterial growth

Psychrophiles, mesophiles, thermophiles, and hyperthermophiles

What class of bacteria grow in around -5 to 20 degrees

Psychrophiles (cold loving)

What class of bacteria grow in around 15 to 45 degrees

Mesophiles (human body temp)

What class of bacteria grow in around 45 to 80 degrees

Thermophiles (hot loving)

What class of bacteria grow in around 65 to 105 degrees

Hyperthermophiles (really hot)

What organisms grows well at high SUGAR concentrations

Yeast, s-cerevisiae

Hemolysis patterns

alpha, beta, gamma

Describe an alpha hemolysis pattern

Partial breakdown of RBC... viridian strep

Describe a beta hemolysis pattern

Complete hemolysis, hemolysins... pathogenic strep

Describe an gamma hemolysis pattern

No hemolysis... enterococcus species

Common traits for streptococcus and enterococcus

Gram positive, no endospore production, strep arrangement, aerotolerant

Blood agars plates are considered to be

Differential plates

Common traits for staphylococcus and micrococcus

Gram positive, tetrad or cluster, no endospore, catalase positive

MSA (mannitol salt agar) plates are

selective (7.5% salt) and differential (mannitol)

Fermented turns

Yellow color

No fermentation

Red color

Micrococcus species are

Strict aerobes

Staphylococcus species are

Facultative anaerobes

MacConkey Agar plate media

Selective (bile salts and crystal violet) and differential (lactose and neutral red)

lactose negative macconkey

no color change

Purpose of BBL enterotube test

Differentiate/identify enterobacteriacea

lactose positive macconkey

Pinkish-fuchsia

How do you determine biocodes and how are they used to determine identity

Giving reach section a positive or negative number rating based on the results... add each section up and get a code that you can look up in a guide

static agents

inhibit or control growth

cidal agents

chemicals that kill organisms

Disinfectants are

used on inanimate objects and surfaces

Antiseptics are

used on living tissue/skin

Factors to evaluate antimicrobial activity

pH, temperature, solubility, initial size of population, interactions with other chemicals

Antibiotics are

Chemical control agents that have an important property of selective toxicity

How do we determine if an organism is easily or not easily killed by an antibiotic

Kirby Bauer disk assay

narrow spectrum

Only effective against one group

broad spectrum

effective against more than one group

The clear disk around an antibiotic on the Kirby Bauer disc is called

The zone of inhibition

The bigger the zone of inhibition

The more sensitive it to it an antibiotic

resistant

Bacteria is not being killed by antibiotic

sensitive

Bacteria is easily killed by antibiotic

What is an ELISA test designed to do?

Detect the present of antibodies that are formed against a specific pathogen

innate immunity

First time of defense, immediate response that is non specific

Examples of innate immunity

Skin, mucus membranes, certain cells, etc.

adaptive immunity

Specific to its target, slower to active and must see the antigen to produce antibodies

Antigen

Derived from the term antibody generating.... Describes anything that can elicit an immune response

What is an epitope?

Part of an antigen

Adaptive immunity forms

Antibodies... secreted by B cells (Y shaped protein)

A given antibody will

Bind to, or lock onto, only a vary narrow range of antigen shapoes

What is the purpose of the chromogen

To produce a color to see if the person is positive or not

Positive ELSIA reactions

Purple

Negative ELSIA reaction

Clear