Question

The bacterium that can tolerate high concentrations of salt and also ferment mannitol is

• A. Staphylococcus aureus
• B. Staphylococcus epidermis
• C. Streptococcus pyogenes
• D. Serratia marcescens

Answer 1

The Correct Option is A

The bacterium that can tolerate high concentrations of salt and also ferment mannitol is Staphylococcus aureus. Let's analyze the options to understand why Staphylococcus aureus is the correct answer:

1. Staphylococcus aureus: This bacterium is known for its ability to thrive in high-salt environments. It can ferment mannitol, producing acid as a byproduct, which is a unique characteristic used in laboratory settings to differentiate it from other bacteria. It is the primary bacterium that changes the color of mannitol salt agar to yellow, indicating fermentation.
2. Staphylococcus epidermis: This species is salt-tolerant but does not ferment mannitol. It grows on mannitol salt agar but the agar remains pink, indicating no fermentation.
3. Streptococcus pyogenes: This bacterium is not known for high salt tolerance and does not ferment mannitol. It requires other agar or growth media for testing.
4. Serratia marcescens: This is not a halophilic bacterium and does not ferment mannitol. It usually produces red pigment and is used in different types of tests.

Therefore, the ability to both tolerate high salt concentrations and ferment mannitol is uniquely attributed to Staphylococcus aureus. This characteristic is commonly utilized in microbiology labs, particularly through the use of mannitol salt agar (MSA), to isolate and identify Staphylococcus aureus.