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Topic 9: Negative Staining

  • The negative stain technique does not stain the bacteria but stains the background.
  • The bacteria will appear clear against a stained backgroun.
  • The stain does not stain the bacteria because of ionic repulsion (the bacteria and the acidic stain both have negative charges)
  • No heat fixing or strong chemicals are used so the bacteria are less distored than other staining procedures.
  • The negative stain technique is useful in situations where other staining techniques don’t clearly indicate cell morphology or size.