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A clear CLED agar plate after cultivation Colonies of lactose and non-lactose fermenting bacteria on CLED agar. CLED agar (cystine–lactose–electrolyte-deficient agar or medium) is a valuable non-inhibitory growth medium used in the isolation and differentiation of urinary microbes.
MacConkey agar is a selective and differential culture medium for bacteria. It is designed to selectively isolate gram-negative and enteric (normally found in the intestinal tract) bacteria and differentiate them based on lactose fermentation. [1] Lactose fermenters turn red or pink on MacConkey agar, and nonfermenters do not change color.
The genus Klebsiella was named after the German microbiologist Edwin Klebs (1834–1913). [citation needed] It is also known as Friedlander's bacillum in honor of Carl Friedländer, a German pathologist, who proposed that this bacterium was the etiological factor for the pneumonia seen especially in immunocompromised individuals such as people with chronic diseases or alcoholics.
The species C. amalonaticus, C. koseri, and C. freundii can use citrate as a sole carbon source. Citrobacter species are differentiated by their ability to convert tryptophan to indole (C. koseri is the only citrobacter to be commonly indole-positive), ferment lactose (C. koseri is a lactose fermentor), and use malonate.
The main type of bacteria used in the production of sauerkraut is of the genus Leuconostoc. [1] [16] As in yogurt, when the acidity rises due to lactic acid-fermenting organisms, many other pathogenic microorganisms are killed. The bacteria produce lactic acid, as well as simple alcohols and other hydrocarbons.
Strong lactose fermenters will appear as dark blue/purple/black, and E.coli (which also ferments lactose) colonies will be dark colored, but will also appear to have a metallic green sheen. Other coliform bacteria will appear as thick, slimy colonies, with non-fermenters being colorless, and weak fermenters being pink. [citation needed]
For example, lactose fermenters turn a deep red when this pH indicator is used. Those bacteria unable to ferment lactose, often referred to as nonlactose fermenters, or NLFs for short, use the peptone in the medium. This releases ammonia, which raises the pH of the medium. Although some authors refer to NLFs as being colourless, in reality they ...
Hektoen enteric agar (HEK, HE or HEA) is a selective and differential agar [1] primarily used to recover Salmonella and Shigella from patient specimens. HEA contains indicators of lactose fermentation and hydrogen sulfide production; as well as inhibitors to prevent the growth of Gram-positive bacteria.