Question

Enterococcus species was the only streptococcus that could grown in NaCl broth. Do you think that enterococcus would be able to grow on Mannitol Slat agar plates? explain?

Answer 1

Enterococcus is a gram positive bacteria that means it has a thick peptidoglycan layer. It is one of the few types of bacteria which can grow on high salt tolerance condition as it produces lactic acid as part of its metabolism, when it uses the mannitol for energy (mannitol it is a type of sugar), acid is secreted. This acid secretion changes the pH of the surrounding agar, which causes it to change from a pink color to yellow. As a result, enterococcus will cause spots of yellow to appear on a mannitol salt plate.