aka acidic stain stains the background, bacteria do not stain with electronegative stain, because both bacteria and dye are electronegative resulting in ionic repulsion.. Advantage is NO FIXING
Gram negative bacteria
Gram positive bacteria
purple after adding counterstain
Steps to gram staining
crystal violet, iodine, alcohol, safaranin
counter stain in gram stain
prevent crystal violet from leaving the cell (iodine) intensifies stain
Gram stain primary stain
Gram stain mordant
iodine ( intensifies the stain) prevents crystal violet from leaving the cell
gram stain decolorizing agent
ethyl alcohol disrupts the lipids coat
gram stain counterstain
safranin ( positive)
Gram positive and negative bacteria may appear if
Bacteria stain poorly or not at all, or older cultures of gram positive bacteria give inconsistent results
crystal violet-iodine can be removed from gram negative bacteria with alcohol because
alcohol is decolorizing agent
Acid fast stain is used to differentiate what bacteria
prevents the entrance of most stains into acid-fast positive cells
primary stain for acid fast stain
recycle and autoclaved before washing and disposing
Chemically defined medium
Medium whose exact chemical composition is known
Most chemoheterotrophic bacteria are grown... Media for which the exact chemical composition varies slightly from batch to batch.
Organic carbon, energy, in the form of meat extracts and partially digested proteins.
commonly used liquid complex medium.
When agar is added it becomes a solid medium
marine red algae with unique properties that make it useful in culture media. Few microbes degrade agar so it remains solid during microbial growth. Liquifies 100 degrees C and remains liquid state until cooled 40 degrees C.
sterilized after preperation in autoclave using steam under pressure.
121degrees C for 15 pounds of pressure for 15 minutes.
Determines the morphology, size and arrangement
Kills microorganisms to observe, and attaches the organism to the slide while preserving structures w/ minimal distortion