Please enable JavaScript.
Coggle requires JavaScript to display documents.
Microbiology (Conditions for Bacterial Growth (Nutritional Requirements…
Microbiology
-
Gram Stain
Gram positive = Violet
-
susceptible to penicillin as it interferes with cross-linking weakening wall structure - osmotic pressure causes cells to burst
-
-
Cell wall of bacteria
Made up of peptidoglycan (murein) arranged in a 3D network of glycan chains (polysaccharides) cross-linked by peptide bridges
-
-
method
-
-
Acetone - alcohol (decolouriser) - removes unbound crystal violet
- (gram negative bacteria lose stain + become colourless) as alcohol penetrates the lipid rich and peptidoglycan layer. Iodine-violet complex is easily removed
- (gram positive bacteria remain purple) peptidoglycan layer becomes dehydrated causing pores in the wall to close. prevents iodine-violet complex escaping
-
-
Aseptic Technique
before culturing bacteria the equipment and media must be sterilised - heat normally used 121'C for 15 minutes
-
-
-
-
-
-
-
-
