The Mechanism of the Gram Reaction. II. The Function of Iodine in the Gram Stain

Mittwer, Tod; Bartholomew, J. W.; Kallman, Burton J.

doi:10.3109/10520295009110986

Cited by 24 publications

(25 citation statements)

References 12 publications

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“…Steam and Steam (1924) and more recently Fischer and Larose (1952) omitted the use of a counterstain in investigations concemed with the gram reaction. Bartholomew and Mittwer (1950) and Bartholomew et at. (1950) It has been suggested frequently that the difference between gram positive and gram negative organisms is quantitative rather than qualitative in nature (Dubos, 1947).…”

Section: Discussionmentioning

confidence: 99%

Quantitative Gram Reaction

1959

Science

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At the present time there is no satisfactory procedure for estimating the degree of gram positivity although the need for a quantitative method is widely recognized. Recently Kennedy and Barbaro (1953) reported an accurate and reproducible method for determining quantitatively the adsorption of crytl violet by bacteria. In addition, the effect of the species and strain of the organism used, the method of killing the cells, and the time in contact with the dye on the quantitative adsorption of crystal violet were studied. The present report describes the application of this quantitative procedure to the gram reaction, the effect of dye concentration on the quantitative adsorption of crystal violet, and the significance of the dye concentration and the counterstain in the gram reaction.

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Section: Discussionmentioning

confidence: 99%

Quantitative Gram Reaction

1959

Science

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“…Further, it has been shown that all the dyes which give Gram differentiation form precipitates with iodine [12]. It seems then that iodine merely serves to accentuate the differentiation, probably by forming some form of complex or precipitate with the adsorbed dye and thereby reducing its ease of removal in alcohol, especially since it has been shown that Gram-positive cells are less permeable to iodine in alcoholic solution than Gram-negative ones [64]. A study of reagents which can replace iodine in the Gram reaction shows Table 1. that each is a mild oxidizing agent and can form a precipitate with Crystal Violet [64].…”

Section: The Role Of Iodine In the Gram Reactionmentioning

confidence: 99%

“…It seems then that iodine merely serves to accentuate the differentiation, probably by forming some form of complex or precipitate with the adsorbed dye and thereby reducing its ease of removal in alcohol, especially since it has been shown that Gram-positive cells are less permeable to iodine in alcoholic solution than Gram-negative ones [64]. A study of reagents which can replace iodine in the Gram reaction shows Table 1. that each is a mild oxidizing agent and can form a precipitate with Crystal Violet [64]. Nevertheless some oxidizing agents and some reagents which form precipitates with Crystal Violet are unsuitable for use in the Gram reaction, and this suggests that iodine must function not merely as an oxidizing agent, nor merely as a precipitating agent, but as a combination of both.…”

Section: The Role Of Iodine In the Gram Reactionmentioning

confidence: 99%

The Dye-Staining of Micro-Organisms: A Review

McKay

1963

Textile Research Journal

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The staining of micro-organisms is an essential feature of microscopy and is also an important aspect of solution adsorption. The present article is an attempt to arouse the interest of physical chemists in the subject of staining mechanisms, which has been to some extent neglected. The general physical and chemical features of the cells of micro-organisms are described in broad terms. The more common staining techniques are described and their mechanisms discussed from the chemist's point of view.

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“…Of 29 dye samples reported on here for the first time none proved to be good substitutes for crystal violet.A previous paper in this series (Mittwer, Bartholomew and Kallman, 1950) indicated that differences in cell membrane permeability to alcoholic iodine were part of the Gram stain mechanism. It was found that, increasing precipitate solubility in alcohol or safranin solution gave decreasing differentiation between Gram-positive and Gram-negative bacteria.…”

mentioning

confidence: 90%

“…A previous paper in this series (Mittwer, Bartholomew and Kallman, 1950) indicated that differences in cell membrane permeability to alcoholic iodine were part of the Gram stain mechanism. Since iodine forms a precipitate with crystal violet, and since the dissolution of this precipitate from the bacterial cell depends on (1) permeability, and (2) general solubility of the precipitate in alcohol and the counterstain, it is clear that a study of dye precipitate solubilities would aid greatly in interpreting the Gram stain mechanism.…”

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confidence: 90%

The Mechanism of the Gram Reaction. III. Solubilities of Dye-Iodine Precipitates and Further Studies of Primary Dye Substitutes

Bartholomew

Mittwer

1951

Stain Technology

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Solubilities of dye-iodine precipitates in alcohol and in aqueous safranin solution were determined by direct solubility methods and by photocolorimetric methods. It was found that, increasing precipitate solubility in alcohol or safranin solution gave decreasing differentiation between Gram-positive and Gram-negative bacteria. Dyes which did not stain the cells well as a primary stain did not give good Gram stains, regardless of the solubilities of their precipitates. Some dyes (typified by methylene blue) which gave relatively alcohol-insoluble iodine precipitates gave inferior Gram differentiation because these precipitates were readily soluble in the safranin counterstain.Solubilities of precipitates of crystal violet and various iodine substitutes were determined photocolorimetrically. The ability of a substance to replace iodine in the Gram stain correlated with its ability to give a precipitate which was only slightly soluble in alcm hol and relatively insoluble in aqueous safranin solution.I t was concluded that the usual Gram reagents are not truly specific for the differentiation. Any dye and mordant could be used if the dye was deeply colored, stained the cells well, and if the precipitate of dye and mordant was only slightly soluble in alcohol and relatively insoluble in the counterstain. These factors, combined with those influencing differences in cell membrane permeability, constitute the most important factors in the Gram stain differentiation.Studies were made concerning the ability of dyes to substitute for rrystal violet in the Gram procedure. Of 29 dye samples reported on here for the first time none proved to be good substitutes for crystal violet.A previous paper in this series (Mittwer, Bartholomew and Kallman, 1950) indicated that differences in cell membrane permeability to alcoholic iodine were part of the Gram stain mechanism. Since iodine forms a precipitate with crystal violet, and since the dissolution of this precipitate from the bacterial cell depends on (1) permeability, and (2) general solubility of the precipitate in alcohol and the counterstain, it is clear that a study of dye precipitate solubilities would aid greatly in interpreting the Gram stain mechanism. It is

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The Mechanism of the Gram Reaction. II. The Function of Iodine in the Gram Stain

Cited by 24 publications

References 12 publications

Quantitative Gram Reaction

Quantitative Gram Reaction

The Dye-Staining of Micro-Organisms: A Review

The Mechanism of the Gram Reaction. III. Solubilities of Dye-Iodine Precipitates and Further Studies of Primary Dye Substitutes

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