Staining Bacteria and Yeasts with Acid Dyes

Various acid dyes prove satisfactory for the routine staining of bacteria. Those used are acid fuchsin, anilin blue w. s., fast acid blue R, fast green FCF, light green, orseilline BB, erythrosin, phloxine and rose bengal. Acid fuchsin, fast green, anilin blue, and orseilline are especially recommended. Phenolic solutions of the dyes, acidified with acetic acid, with the addition of ferric chloride to those containing acid fuchsin, anilin blue, fast green or light green, are used. Procedures are given in detail for staining or demonstrating vegetative cells, resting and germinating spores, capsules, sheaths and glycogen in bacteria; germinating and conjugating spores of yeast; and for counterstaining after acid fast or Gram staining. The principal advantages of using acid dyes are better differentiation, and less tendency for slime amd debris to take the dye.