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Scanning about the microbiologic community, a few references to Gram pos bacteria growing on MacConkey's showed up. One reports a Gram positive rod of unspecified species (see links). Another article says some forms of Enterococcus and Staphylococcus can grow in spite of the bile salts that make this medium so antagonistic to Gram positives. But just as many articles opine that, if this happens, the medium may not have been properly prepared.
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∙ 15y ago
Wiki User
∙ 13y agoStaphylococcus and Enterococcus (group d streptococcus)
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What are the MacConkey test results for s epidermidis?
There is no growth because S.Epidermidis is a gram positive bacteria. MacConkey selects for gram negatives. the bile salts and crystal violet inhibit gram positive growth in the medium
Why most of the gram positive bacteria cannot grow on MacConkey Agar?
gram positive bacteria cannot grow due to the presence of bile salts and crystal violet in maConkey media.
How would removing the crystal violet from MacConkey agar alter the sensitivity and specificity of the medium?
It would allow growth of Gram-positive cocci.
Which gram negative bacteria do not grow on macconkey and EMB?
humein ni pata
Is lactobacillus casei is a gram negative bacteria or gram positive?
The Bacteria Sarcina lutea is Gram Positive Because If You Perform the Gram Test It Will Turn The Violet Color Which indicates It's Positiveness. What Makes It Positive Is the Peptidoglycan Located Within The The Bacterium
What are the MacConkey test results for s epidermidis?
There is no growth because S.Epidermidis is a gram positive bacteria. MacConkey selects for gram negatives. the bile salts and crystal violet inhibit gram positive growth in the medium
Crystal violet in the MacConkey agar?
MacConkey's agar refers to a culture medium that is designed to selectively grow Gram-negative bacteria. It contains crystal violet dye, which inhibits certain Gram-positive bacteria.
Macconkey agar is a selective medium and it is also a defined or a undefined medium so why is that a formulation desirable?
This type of agar is designed to grow gram-negative bacteria. It will not grow gram-positive bacteria due to a dye in the formula of the agar.
Does micrococcus luteus 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)
Role of bile salt in macconkey agar?
it inhibits the growth of Gram positive bacteria
Why most of the gram positive bacteria cannot grow on MacConkey Agar?
gram positive bacteria cannot grow due to the presence of bile salts and crystal violet in maConkey media.
What is macconkey agar made out of?
Macconkey agar consists of agar, lactose, peptone, neutral red dye, crystal violet dye & bile salts. Bile salts inhibit growth of Gram positive bacteria & allow growth of Gram negative bacteria only. It differentiates lactose fermentating Gram negative bacteria from non lactose fermentating Gram negative bacteria.
Which gram positive bacteria grows on macconkey and EMB?
Gram + bacteria do NOT grow on EMB agar, EMB agar inhibits their growth, and is selective for Gram -
How would removing the crystal violet from MacConkey agar alter the sensitivity and specificity of the medium?
It would allow growth of Gram-positive cocci.
Which gram negative bacteria do not grow on macconkey and EMB?
humein ni pata
Can treatment with Transpeptidase eliminate gram positive bacteria from a mixture of gram positive bacteria and gram negative bacteria?
No. A treatment of ethylenediaminetetraacetic acid (EDTA) and the enzyme, lysozyme, will cause gram negative bacteria to lyse. Some gram positive bacteria can also be lysed by doing this. The EDTA stabilizes the solution and allows lysozyme to cut the bonds between the carbohydrates that make up the cell wall wall in bacteria. This will lyse the cell and cause the contents of the cell to be spilled out. This technique is primarily used for DNA assays. A good way to isolate either gram positive or gram negative is by using different types of agar. The MacConkey agarmight be the most useful for what you want to do. It will only allow gram negative to grow, isolating just the gram negatives only.
Can you elimintate gram positive bacteria from a gram positive gram negative mixture with mild detergent treatment?
AnswerYou can use a "selective" medium that will inhibit the growth of Gram positive bacteria and only allow Gram negative bacteria to multiply. A medium which is commonly used for this is the McConkey agar which contains a crystal violet strain and allows only Gram negative cultures to grow.You can also eliminate Gram positive bacteria with antibiotics (e.g. ampicillin) provided that they are sensitive and not resistant.
