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Mannitol Salt Agar (MSA) is a selective/differential media that inhibits the growth of gram negative bacteria. Only a few bacteria can tolerate the 7.5% NaCl found within this media. The high salt content selects for Staphylococcus and a few salt tolerant enterococci. The presence of the sugar mannitol gives this media its differential properties. When mannitol is fermented (utilized by the bacteria) microorganisms release acidic byproducts that change the pH of the surrounding media. The pH change is indicated by a change in the pH indicator (phenol red) from pink to yellow.
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∙ 15y ago
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∙ 13y agoMannitol salt agar is a selective and differential primary culture medium useful in recovery and identification of staphylococci from specimens containing mixed flora. The high salt concentration (7.5%) inhibits most gram-negative and gram-positive bacteria except Staphylococcus species. Staphylococcus aureus is able to ferment mannitol, the sole carbohydrate in the medium, to produce acid products. This lowers the pH and changes the color of the pH indicator, phenol red, to yellow. Colonies of S. aureus typically appear yellow, surrounded by a yellow zone. Other Staphylococcus and Micrococcusspecies usually do not ferment mannitol and therefore produced reddish colonies that may exhibit a red to purple surrounding zone due to peptone breakdown.
Reference:
Mahon, C. Manuselis, George: Textbook of Diagnostic Microbiology 2nd Edition 2000; Selected Bacteriologic Culture Media APPENDIX A (pg. 1130)
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What selective agent found in Mannitol Salt Agar?
The high salt concentration (7.5-10% w/v) makes the agar hard for all but staph spp. To grow, and staph aureus turns yellow when it ferments the mannitol.
How do mannitol-salt agar tests work?
Mannitol salt agar supports growth of organisms that can grow in a high salt concentration, particularly Staphylococcus species and halophiles. The phenol red pH indicator in the agar will also let you know whether or not the bacterium you streaked ferments mannitol by changing to a yellow color if fermentation has occured.
Did lactobacillus grow on mannitol salt agar?
Yes. M. smegmatis is a gram + bacteria, and MSA plates select for gram + bacteria.
Does Mycobacterium phlei grow on EMB agar?
yes it can be grow in EMB agar.
Can Lactobacillus grow on blood agar?
yes
What selective agent found in Mannitol Salt Agar?
The high salt concentration (7.5-10% w/v) makes the agar hard for all but staph spp. To grow, and staph aureus turns yellow when it ferments the mannitol.
Can Klebsiella pneumoniae grow on Mannitol salt agar?
No, K. pneumoniae will not grow on Mannitol Salt Agar- gram negative organisms cannot grow on MSA, and K. pneumoniae is gram negative.
Why does gram-positive bacteria grow in mannitol agar?
Gram-positive bacteria grows in Mannitol agar because it contains a high level of salt. This type of agar allows only certain types of bacteria to grow, making it selective.Ê
Can serratia marcescens grow in mannitol salt agar?
No it doesn't because it doesn't ferment mannitol. P. mirabilis can actually grow on a MAC agar, but it is colorless. I actually had this lab in Micro260 today.An MSA agar has 7% high salt concentration and provides growth for S. aureus bacteria turning it yellow/gold. An MSA agar is selective for osmotolerant bacteria meaning for bacteria that can grow in different salt concentrations, and it's differential because it can ferment mannitol.
Can Streptococcus grow on MSA?
MSA stands for mannitol salt agar. Streptococcus can not grow on this type of agar. This is because it has a very high salt content, which allows only certain microorganisms to grow in it.
How do mannitol-salt agar tests work?
Mannitol salt agar supports growth of organisms that can grow in a high salt concentration, particularly Staphylococcus species and halophiles. The phenol red pH indicator in the agar will also let you know whether or not the bacterium you streaked ferments mannitol by changing to a yellow color if fermentation has occured.
Can enterobacter aerogenes grow on mannitol salt agar?
the bacteria dont ferment in MSA, there is no growth on the plat
Did lactobacillus grow on mannitol salt agar?
Yes. M. smegmatis is a gram + bacteria, and MSA plates select for gram + bacteria.
Purpose of high salt concentration in the mannitol salt agar medium?
Mannitol salt agar (MSA) contains high levels of salt because it inhibits the growth of most bacteria. This makes it an excellent medium to test for Staphylococci and Micrococcaceae as they are tolerant of high levels of NaCl.
What the purpose of mannitol salt?
The purpose is to select for salt-tolerant microbes. Most species of microbes can't grow in such a salty environment. The only genus that can culture on an MSA plate is Staphylococcus. The only species of Staphylococcus that can ferment Mannitol is Staph. Aureus. If the plate turns yellow, you know that Mannitol was fermented into an acid, which only Staph. Aureus can do. If there is a little growth (aka the culture is red) then it's still most likely a species of Staph such as Staph. epidermidis. If there is no growth, as in E. coli, then there will be no culture and no change in color.
Which ingredient supplies carbon in the mannitol salt agar?
mannitol is a type of sugar, so it supplies the carbon in the MSA medium
Why can mannitol salt agar and EMB agar be described as both selective and differential media?
it is selective because only a salt tolerant can grow. 7.5 nacl it has diffrential properties also. if mannitol formentors turns yellow staphlococus aureus; but if it has no change then its a nonpathogenic staphlococci (s. edermis)
