Quick Answer: Would Removing Bile Salts From He Agar?

What is the role of bile salts in he Agar?

Bile salts render the medium selective, inhibiting Gram positive organisms and reducing growth of some gram-negative organisms other than Salmonella and Shigella.

Lactose, sucrose and salicin are included for optimal differentiation by the color of the colonies and of the medium adjacent to the colonies..

Is Pea Agar A differential?

Phenylethyl Alcohol Agar (PEA) PEA selects for the growth of gram positive organisms by inhibiting the growth of gram negative bacilli. … Eosin–Methylene Blue (EMB) Agar is a selective and differential medium used to enhance selection of gram negative bacteria.

What is the application purpose of he Agar?

HE agar is another plating medium used for the isolation and differentiation of Salmonella from foods. This medium uses the bile salts, acid fuchsin, and bromthymol blue as selective agents to inhibit Gram-positive organisms, but these agents can also be toxic to some Gram-negative organisms.

Is he Agar a defined or undefined medium?

Is HE agar a defined or an undefined medium? It is undefined due to the yeast extract and peptic digest of animal tissue in the medium. An undefined medium is desirable to support growth of a wide variety of the organisms being selected for.

Is chocolate agar selective or differential?

Chocolate agar, a differential medium for gram-positive cocci.

What ingredients does MacConkey Agar Supply?

Which ingredients in MacConkey agar supplies carbon? Gelatin, casein (milk protein), animal tissue, lactose, and to some extent, bile salts are potential sources of carbon.

Why is pea agar not a differential media?

PEA is not considered a differential media because a differential media contains chemical indicators that allow microbiologists to distinguish two or more species of bacteria. … PEA is selective because it inhibits gram negative bacteria while encouraging growth of gram positive bacteria.

Why can mannitol salt agar and EMB?

Why can mannitol salt agar and EMB agar be described as both selective and differential media? They encourage the growth of both gram negative and gram positive bacteria. Mannitol salt agar is used to isolate staphylococci from clinical and nonclinical samples. EMB agar is used for the detection of E.

Is MacConkey agar selective or differential?

MacConkey agar is a selective and differentiating agar that only grows gram-negative bacterial species; it can further differentiate the gram-negative organisms based on their lactose metabolism.

Is blood agar selective or differential?

Blood Agar This medium can be made selective by the addition of antibiotics. This medium is differential because: Blood Agar tests for the production of hemolysin which breaks down red blood cells.

Would removal of Oxgall from Bea?

Oxgall is the selective agent in BEA that makes the medium too basic for the tolerance of most organisms. … Removal of oxgall would decrease the medium’s specificity. The oxgall selects against negative results. Its removal would allow for otherwise negative results to successfully grow and appear falsely positive.

Would removal of sodium chloride from MSA?

Yes, the removal of sodium chloride from MSA will alter the medium’s sensitivity or specificity to a great extent.

Were the uninoculated controls positive or negative controls?

Were the uninoculated controls in this lab positive or negative, and what purpose did they serve? The controls were negative, and served as color comparison for experimental tubes as well as verification for media sterility.

Does E coli grow on pea?

Phenylethyl alcohol (PEA) agar allows growth of gram-positive organisms, particularly cocci, while inhibiting most gram-negative bacteria and fungi. … Typically PEA agar is used to inhibit common contaminants such as Escherichia coli and Proteus species.