gram-negative

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gram-negative

 [gram-neg´ah-tiv]
losing the stain or decolorized by alcohol in Gram's method of staining; see Gram stain. This is a primary characteristic of bacteria having a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of lipoprotein and lipopolysaccharide.

gram-neg·a·tive

(gram-neg'ă-tiv), In this expression gram begins with lowercase g but Gram stain takes an uppercase G.
Refers to the inability of a type of bacterium to resist decolorization with alcohol after being treated with crystal violet. However, following decolorization, these bacteria can be readily counterstained with safranin, imparting a pink or red color to them when viewed by light microscopy. This reaction is usually an indication that the outer structure of the bacterium consists of a cytoplasmic (inner) membrane surrounded by a relatively thin peptidoglycan layer, which in turn is surrounded by an outer membrane. See: Gram stain.

gram-negative

or

Gram-negative

(grăm′nĕg′ə-tĭv)
adj.
Of, relating to, or being a bacterium that does not retain the violet stain used in the Gram stain method.

gram-neg·a·tive

(gram-neg'ă-tiv)
Refers to the inability of a bacterium to resist decolorization with alcohol after being treated with Gram crystal violet. However, following decolorization, these bacteria can be readily counterstained with safranin, imparting a pink or red color to the bacterium when viewed by light microscopy.
See: Gram stain

Gram-negative

see GRAM'S STAIN.

Gram-negative

Refers to the property of many bacteria that causes them to not take up color with Gram's stain, a method which is used to identify bacteria. Gram-positive bacteria which take up the stain turn purple, while Gram-negative bacteria which do not take up the stain turn red.

gram-neg·a·tive

(gram-neg'ă-tiv)
Refers to the inability of a type of bacterium to resist decolorization with alcohol after being treated with crystal violet.