Final answer:
The unknown Staphylococcus species can grow on MSA, indicating it is halotolerant. If mannitol fermentation occurs, as evidenced by a yellow color change, it suggests the organism could be Staphylococcus aureus.
Step-by-step explanation:
The Mannitol Salt Agar (MSA) plate is utilized to differentiate staphylococcus species and to identify their traits such as tolerance to high salt concentrations and the ability to ferment mannitol. If an unknown Staphylococcus species can grow on this medium, it implies it is halotolerant, capable of thriving in the presence of high sodium chloride levels. Should the medium's color change from red to yellow around the colonies, this indicates positive fermentation of mannitol, suggesting the production of acid, which lowers the pH and turns the phenol red indicator yellow.
Therefore, we can conclude that the unknown organism is halotolerant since it grows on MSA, and if the color around its colonies is yellow, it successfully ferments mannitol, pointing towards potential identification as Staphylococcus aureus.