What organism produce mucoid colonies?

Some organisms, especially Klebsiella and Enterobacter, produce mucoid colonies which appear very moist and sticky and slimy This phenomenon happens because the organism is producing a capsule, which is predominantly made from the lactose sugar in the agar.

What colonies grow on MacConkey agar?

MacConkey Agar is a solid, selective and differential agar that only cultivates gram-negative bacterial species, it can further differentiate Gram-negative organisms based on their lactose metabolism: Lactose fermenters, colonies, turn red or pink on MacConkey agar. Non-fermenters do not change color.

Does Staphylococcus grow on MacConkey agar?

MacConkey agar selects for organisms like Escherichia coli (Gram negative bacilli) while inhibiting the growth of organisms like Staphylococcus aureus (Gram positive cocci).

What types of bacteria are inhibited on MacConkey agar?

2. What types of bacteria are inhibited on MacConkey agar? Gram-positive bacteria are inhibited on MacConkey agar.

Does Shigella grow on MacConkey agar?

Shigella grows as non-lactose-fermenting colonies on MacConkey agar, although a more selective agar is used for the isolation of Shigella from feces, such as deoxycholate citrate agar and xylose lysine deoxycholate agar.

Can Neisseria gonorrhoeae grow on MacConkey agar?

Note: Neisseria does not grow on MacConkey. Note: Growth, but no fermentation of lactose. Colorless colonies, medium is slightly yellow due to the increased pH resulting from bacterial digestion of peptone in the medium. Note: Gram-positives do not grow on MacConkey.

What would you expect to see if you culture Gram-positive lactose fermenting bacteria on MacConkey?

what do you expect to see on MacConkey agar medium? lactose fermenting bacteria produce colonies that are various shades of red because of the conversion of the nuetral red indicator dye (red below pH 6.8) from the production of mixed acids. non-lactose fermenting bacteria colonies will appear colorless or transparent.

How do you interpret MacConkey agar?

Result Interpretation on MacConkey Agar Lactose fermenting strains grow as red or pink and may be surrounded by a zone of acid precipitated bile. The red colour is due to production of acid from lactose, absorption of neutral red and a subsequent colour change of the dye when the pH of medium falls below 6.8.

Why Staphylococcus does not grow in MacConkey agar?

MacConkey Agar without Crystal Violet The lack of crystal violet permits the growth of Staphylococcus and Enterococcus. Staphylococci produce pale pink to red colonies and enterococci produce compact tiny red colonies either on or beneath the surface of the medium.

Why does Staphylococcus epidermidis not grow on MacConkey agar?

The pink color of the bacterial growth indicates E. coli is able to ferment lactose. Quadrant 3: Absence of growth indicates the organism, Staphylococcus epidermidis, is inhibited by bile salts and crystal violet and is a gram-positive bacterium.

What types of bacteria are inhibited on MacConkey agar what ingredients in MacConkey agar selects against those bacteria?

This medium is both selective and differential. The selective ingredients are the bile salts and the dye, crystal violet which inhibit the growth of Gram-positive bacteria. The differential ingredient is lactose.

Does Klebsiella grow on MacConkey agar?

⇒ Special requirements – Klebsiella pneumoniae has no complex nutritional requirements and readily grows in ordinary media like Nutrient Agar medium (NAM). Commonly the NAM & MacConkey Agar medium is used for the cultivation of Klebsiella pneumoniae in the Laboratory.