| gram-negative oxygenic photosynthetic bacteria | <microbiology> Widely distributed unicellular or multicellular bacteria. The cyanobacteria use chlorophyll a and phycobilins for oxygenic photosynthesis while genera in the prochlorales use both chlorophyll a and b but not phycobilins. (12 Dec 1998) |
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| gram-positive | <microbiology> Bacteria that retain the stain or that are resistant to decolourisation by alcohol during Gram's method of staining. This is a primary characteristic of bacteria whose cell wall is composed of a thick layer of peptidologlycan containing teichoic and lipoteichoic acid complexed to the peptidoglycan. See: gram-negative (06 Oct 1997) |
| gram-positive asporogenous rods | <microbiology> A gram-positive, non-spore-forming group of bacteria comprising organisms that have morphological and physiological characteristics in common. (12 Dec 1998) |
| gram-positive asporogenous rods, irregular | <microbiology> A group of irregular rod-shaped bacteria that stain gram-positive and do not produce endospores. (12 Dec 1998) |
| gram-positive asporogenous rods, regular | <microbiology> A group of regular rod-shaped bacteria that stain gram-positive and do not produce endospores. (12 Dec 1998) |
| gram-positive bacteria | <microbiology> Bacteria which retain the crystal violet stain when treated by gram's method. (12 Dec 1998) |
| gram-positive bacterial infections | <microbiology> Infections caused by bacteria that retain the crystal violet stain (positive) when treated by the gram-staining method. (12 Dec 1998) |
| gram-positive cocci | <microbiology> Coccus-shaped bacteria that retain the crystal violet stain when treated by gram's method. (12 Dec 1998) |
| gram-positive endospore-forming bacteria | <microbiology> Bacteria that form endospores and are gram-positive. Representative genera include bacillus, clostridium, micromonospora, saccharopolyspora, and streptomyces. (12 Dec 1998) |
| gram-positive endospore-forming rods | <microbiology> Rod-shaped bacteria that form endospores and are gram-positive. Representative genera include bacillus and clostridium. (12 Dec 1998) |
| gram-positive rods | <microbiology> A large group of rod-shaped bacteria that retains the crystal violet stain when treated by gram's method. (12 Dec 1998) |
| Gram's iodine | <microbiology> A solution containing iodine and potassium iodide, used in Gram's stain. (05 Mar 2000) |
| Gram's stain | <microbiology, technique> A method for differential staining of bacteria; smears are fixed by flaming, stained in a solution of crystal violet, treated with iodine solution, rinsed, decolorised, and then counterstained with safranin O. Gram-positive organisms stain purple black and Gram-negative organisms stain pink; useful in bacterial taxonomy and identification, and also in indicating fundamental differences in cell wall structure. (05 Mar 2000) |
| Gram stain | <microbiology, procedure> A method of staining bacteria using a violet stain. The gram staining characteristics (denoted as positive or negative) can assist in the identification of the offending bacteria. A heat fixed bacterial smear is stained with crystal violet (methyl violet), treated with 3% iodine/potassium iodide solution, washed with alcohol and counterstained. The method differentiates bacteria into two main classes, gram-positive and gram-negative. Certain bacteria, notably mycobacteria, that have walls with high lipid content show acid-fast staining the stain resists decolouration in strong acid. (27 Sep 1997) |
| Weigert-Gram stain | <technique> A stain for bacteria in tissues in which sections are stained in alum-haematoxylin, then in eosin, aniline methyl violet, and Lugol's solution. (05 Mar 2000) |