micro- selective and differential media

Purpose of Gaspak for anaerobes?

Absorbs oxygen, O2 free environment

Purpose of Gaspak for capnophiles?

Allows environment to be high in CO2

How does the appearance of the two types of Gaspaks used in lab differ?

Labels are different, sizes are different, and colors of labeling

When is H2O2 produced in a cell?

As a byproduct of respiration

What is the name of the enzyme that breaks down H2O2 ?

Catalase

What is the gram reaction and cell morphology of the organisms that we preform a catalase test on?

G+ cocci

A negative catalase test indicates the presence of the genus:

Streptococcus

A positive catalase test indicates the presence of the genus:

Staphylococcus

The capnophilic genus that we will work with is called:

Streptococcus

The oxidase test detects the enzyme?

Cytochrome oxidase C

What function does the analyze in the oxidase test perform in cellular respiration?

Places the electron on oxygen, transfers electrons from donor molecule to oxygen

The oxidase test is preformed on organisms with what gram reaction?

G-

The family of organisms that test negative in the oxidase test is:

Enterobacteriaceae

Enterobacteriaceae- have the gram reaction of?

G-, bacilli, N/A arrangement

The organisms in the above family (Enterobacteriaceae) can primarily be found where in/on the human body?

Intestines

The organisms in the above family (Enterobacteriaceae) can ____ carbohydrates when placed in anaerobic conditions

Ferment

An organism that grows best with oxygen, but who can regenerate coenzymes and expel private under anaerobic conditions are called____

Facultative Anaerobes

Describe two genera that are oxidase positive, include gram reaction and disease discussed.

1. Pseudomonas: G-, Bacillus, infects burns, cuts, and lungs

2. Neisseria: G-, Diplococci, meningitis, stiff neck

what is selective media?

media that contains components which prevent growth in some organisms while others flourish

what is differential media?

contains components that allows us to see differences in closely related organisms

what is enriched media?

has extra nutrients assed for specific organism growth

what organisms will grow on TBAB? what organisms will NOT grow on TBAB?

1. all can grow w/out additional nutrient needs

2. Fastidious organisms will NOT grow

what is the only organism you must be able to identify when grown on TBAB and how will you identify the organism?

Pseudomonas aeruginosa-

• Pyoverdine: green

• Pyocyanin: blue

what organism will grow on TSA? what organism will NOT grow on TSA?

almost all will grow, and Neisseria will not grow

what makes TSA differential ?

exoenzymes in agar

what is an exoenzyme?

enzymes secreted in the environment

what two exoenzymes can be detected by TSA and how can we tell them apart?

• Alpha Hemolysins: partial breakdown RBC/greenish color

• Beta Hemolysins: complete breakdown of RBC/hemoglobin

what do we call it when an organism grows on TSA, but does not produce either of the exoenzymes above?

Gamma Hemolysins

Species in what genus are differentiated by the exoenzymes that can be detected by TSA ?

Streptococcus

What makes MSA selective?

NACI 7.5%

what is the differential agent in MSA?

mannitol - sugar alcohol

what characteristic describes organisms that will grow on MSA and what genus of those organisms will we work with?

Streptococcus aureus, halophiles

what organism can we differentiate using MSA and what characteristic of the organisms allows us to differentiates those organisms?

differentiation of mannitol, halophiles

what color will the media be for each of the organisms above? (mannitol, halophiles)

yellow

what are the selective agents in MacConkey agar?

bile salts and crystal violet

what is the differential agen in MacConkey agar?

lactose

what organisms will grow in MacConkey agar?

Enterics, Microorganisms that live in the intestines, normal flora

what organisms will NOT grow in MacConkey agar?

G+

what two groups of organisms can be differentiated on MacConkey?

organisms that ferment lactose and ones that do not ferment lactose

organisms that show a positive reaction to the differential agent in MacConkey agar can normally be found in what part of the human body?

intestines

what color are colonies that show a positive reaction to the differential agent in MacConkey agar

Pink

what color are colonies that show a negative reaction to the differential agent in MacConkey agar?

normal color, colorless

what is the main selective agent for Hektoen?

bile salt

what are the two differential agents for Hektoen?

lactose and thiosulfate

what groups of organisms can be differentiated by the above agents (Hektoen)?

Salmonella ad Shigella

what is the basis of black colonies on Hektoen agar?

Salmonella

what two genera can be differentiated on Hektoen? what diseases do they cause?

Salmonella: Gastroenteritis

Shigella: food poisoning

what are the two primary functions of fermentation?

regenerate NAD and get rid of pyruvate

phenol red broths are used to differentiate organisms in the family _____

Enterobacteriaceae

substances added to phenol red broths to differentiate organisms are ____

1 carbohydrate

what piece of glassware allows us to detect gas product in fermentation broths?

durham tubes

What would cause the media to exhibit fuchsia color?

deamination has occurred, NH2 removed from peptide creating ammonia

Simmons Citrate agar tests the ability of an organism to use what substance as a carbon source?

citrate

what color does the Simmons Citrate media turn if the organism grows?

blue

Citrate agr is used to differentiate species in what family?

Enterobacteriaceae

What is the selective agent in Bile Esculin agar?

40% blue

what is the differential agent in Bile Esculin agar?

esculin, organisms hydrolyse esculin- changes the color

what is the appearance of a postive reaction on bile esculin agar?

black

what two genera are differentiated by bile esculin agar?

streptococcus and entercoccus

why is it necessary to have specific test to differentiate : streptococcus and entercoccus

because the produce different infections, need to find treatment for correct one

what is the reagent used to detect the exoenzyme coagulase?

rabbit serum

what is the specific substance in that reagent that interacts with coagulase?

fibrinogen

what organisms are differentiated by the coagulase test?

pathogenic staphylococci

what is the appearance of a postive reaction in the coagulase test?

gelled, snot like