Staphylococcus will not grow on Mac since crystal violet inhibits the growth of Gram positivesfmchinea: Actually some species of staphylococcus grow on MacConkey's plate including Staphylococcus aureus.
yesTypically, MSA is used to isolate and differentiate various staphylcocci, some of which are pathogenic, like S. aureus, or non pathogenic like S. epidermidis. Staph are the only kind of bacteria that will grow on MSA. S. aureus is the only staph that ferments manitol. Meaning, MSA can be used to isolate pathogenic from non-pathogenic staph.source: biology major
No, Alcaligenes faecalis will not grow on MacConkey agar. MacConkey agar is selective for gram-negative bacteria that ferment lactose. Alcaligenes faecalis is a gram-negative bacteria that does not ferment lactose, so it will not grow on MacConkey agar.
MacConkey agar is designed to grow Gram-negative bacteria and also contains crystal violet dye which inhibits the growth of Gram-positive bacteria. Since S. aureus is Gram-positive it should not grow on MacConkey agar. No. MacConkey agar inhibits MOST of the Gram-positive bacteria. There are some Gram-positive bacteria that can tolerate bile-salt are able to grow in MacConkey agar. Enterococcus and some species of Staphylococcus are able to grow in MacConkey. (lack citation though)
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MacConkey agar
Lac+ bacteria is acid base color indicator that lowers the pH of the MacConkey agar. The MacConkey agar contains neutral red dye, lactose, peptone, and crystal violet dye.
MacConkey agar contains agar as a solidifying agent which solidifies at room temperature to provide a solid surface for bacterial growth and colony isolation. MacConkey broth, on the other hand, does not contain agar and remains liquid at room temperature to allow for easier culture of bacteria in liquid medium for metabolic studies or growth analyses.
Enterococcus faecalis typically does not grow on MacConkey agar as this selective and differential medium is primarily used for isolating and differentiating members of the Enterobacteriaceae family, which are mostly gram-negative bacteria. Enterococcus species are gram-positive bacteria and do not ferment lactose, the key ingredient in MacConkey agar that allows for differentiation.
E. coli that grow on MacConkey agar typically exhibit lactose fermentation, causing them to produce pink or red colonies. These colonies may also appear mucoid due to the production of a polysaccharide capsule. Additionally, E. coli on MacConkey agar will typically not grow well under acidic conditions, as the agar contains crystal violet which inhibits the growth of Gram-positive bacteria.
Most gram positive bacteria do not grow on MacConkey agar or Eosin Methylene Blue (EMB) agar, as these are selective media designed to inhibit the growth of gram positive organisms. So, typically, you would not expect a gram positive bacteria to grow on these media.
Bile salts in MacConkey agar inhibit the growth of Gram-positive bacteria by disrupting their cell membranes. This selective property allows for the preferential growth of Gram-negative bacteria on MacConkey agar, making it a useful medium for the isolation and differentiation of enteric bacteria.