Admin Table of Contents
What ingredients are in EMB supplies?
EMB agar is composed of agar, peptone, lactose, sucrose, dipotassium phosphate, and two dyes: eosin Y and methylene blue.
What do you expect to see on the MSA and Na plates?
Growth on the MSA and NA plates was recorded as “good growth”, “poor growth” or “no growth”. These are qualitative and, at least for the first two, subjective terms. This means that bacteria that are sensative to salt would grow on the NA, but not on the MSA.
Which culture medium has neutral red added as a pH indicator?
MacConkey agar is also a differential medium. The lactose fermenters produce acid, which turns the medium and the colonies of strong fermenters hot pink. The medium is supplemented with the pH indicator neutral red, which turns to hot pink at low pH.
What pathogen is best identified using a SMAC Agar?
Sorbitol-MacConkey agar, also known as SMAC, is a variant of MacConkey agar specifically formulated to detect the presence of the pathogenic strain of Escherichia coli O157:H7.
What is the carbon source in EMB?
Peptic digest of animal tissue serves as source of carbon, nitrogen, and other essential growth nutrients. Lactose serves as the source of energy by being the fermentable carbohydrate. Eosin-Y and methylene blue serve as differential indicators.
What chemical ingredient makes MSA selective?
The differential ingredient in MSA is the sugar mannitol. Organisms capable of using mannitol as a food source will produce acidic byproducts of fermentation that will lower the pH of the media. The acidity of the media will cause the pH indicator, phenol red, to turn yellow.
What chemical makes MSA differential How?
sugar mannitol
The differential ingredient in MSA is the sugar mannitol. Organisms capable of using mannitol as a food source will produce acidic byproducts of fermentation that will lower the pH of the media. The acidity of the media will cause the pH indicator, phenol red, to turn yellow.
Why do bacteria ferment lactose?
The three sugars are glucose (monosaccharide), sucrose and lactose (both disaccharides). Generally, a bacterium will use the glucose first for energy production, and then if it has the enzymes sucrase and/or lactase, it will ferment the disaccharides for energy production. This produces acids, lowering the pH.
What agar is used for E. coli?
Brilliance™ E. coli/coliform Selective Agar (formerly Chromogenic E. coli/coliform Selective Agar) is for the detection and enumeration of Escherichia coli and other coliforms from food and water samples.
What bacteria ferments sorbitol?
Non-pathogenic strains of E. coli ferment sorbitol to produce acid: Pathogenic E. coli cannot ferment sorbitol, so this strain uses peptone to grow.