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What else can I help you with?
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.
Function of crystal violet?
Crystal violet is a hexamethyl also known as methyl violet 10B This is much darker than 2B, and often darker than 6B. It is used in biological stainang particularly gram staining together with safranin and iodine. Crystal violet was also used to treat strept throat. Doctors used to swab it on the back of your throat.
How do you determine when a loop is cool?
Touch it to the sterile agar in a plate. If it melts the agar, it is still hot. If it doesn't melt the agar, then it is cool enough.
What is melting point of agar?
85C
In the diffusion of liquids through agar what characteristic of liquid determines the rate at which it will travel through the agar?
The size of the molecules.
Does Staphylococcus grow on non crystal violet MacConkey agar?
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.
What is the name of the acide base color indicator found in 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.
Does enterococcus faecalis grow on macConkey agar?
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.
What is the indicator that turns the agar medium pink with copper?
MacConkey agar contains bile salts, lactose, peptone. crystal violet dye, and neutral red dye. The agar appears a medium pink with a copper undertone.
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)
Why most of the gram positive bacteria cannot grow on MacConkey Agar?
Most gram positive bacteria cannot grow on MacConkey Agar because the agar contains crystal violet and bile salts that inhibit the growth of gram positive organisms. Additionally, the agar is designed to selectively isolate and differentiate gram negative bacteria based on their ability to ferment lactose, producing pink colonies.
How would removing the crystal violet from MacConkey agar alter the sensitivity and specificity of the medium?
Removing crystal violet from MacConkey agar would decrease its specificity by allowing more non-selective bacteria to grow on the medium, potentially leading to false-positive results. The sensitivity may also decrease as the absence of crystal violet could affect the medium's ability to inhibit the growth of certain bacteria, thereby reducing its ability to detect specific microbial species.
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.
What is the culture characteristic of Ecoli thst grow on macconkey agar?
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.
What type of medium is macconkey agar?
MacConkey agar is a selective and differential medium used in microbiology for the isolation and identification of Gram-negative bacteria, particularly Enterobacteriaceae. It selects for growth of these bacteria by inhibiting the growth of Gram-positive organisms through the use of crystal violet and bile salts. It also differentiates between lactose-fermenting and non-lactose-fermenting bacteria based on the color change of colonies.
Why staph aureus grows on macconkey agar?
Staphylococcus aureus does not typically grow on MacConkey agar, as this medium is selective for Gram-negative bacteria, particularly Enterobacteriaceae, due to its bile salts and crystal violet dye that inhibit Gram-positive organisms. However, if S. aureus is observed on MacConkey agar, it may be due to contamination or the presence of certain strains that can tolerate the inhibitory conditions. Generally, for the isolation of S. aureus, media such as mannitol salt agar is more appropriate since it is selective for staphylococci.
Is MacConkey agar a chemically defined orn complex nedia and why?
MacConkey agar is classified as a complex medium because it contains a variety of ingredients, including peptones, bile salts, and crystal violet, which provide nutrients and inhibit the growth of Gram-positive bacteria. It is not chemically defined since the exact composition of the peptones is unknown and can vary. The primary purpose of MacConkey agar is to differentiate lactose fermenters from non-fermenters, with lactose fermenters producing acid that changes the color of the medium.
