Gram staining & steps

gram-negative bacteria characteristics

very thin peptidoglycan layer & an outer membrane, which together make up cell envelope

gram-positive bacteria characterisitcs

has a thick peptidoglycan layer, remains purple

step 1

smear one loop of the mixed bacteria from the secondary culture bottle

step 2

heat fix by passing the slide over the flame until it becomes dry

step 3

cover the smear with crystal violet and let stand for 20 seconds

step 4

wash till liquid runs clear

step 5

cover with smear with gram's iodine solution and let it stand for one minute

step 6

flood the smear with 95% ethly alcohol for around 5-15 seconds

step 7

stop the action of alcohol by rinsing the slide with water from wash bottle for a few seconds

step 8

cover the smear with safranin for 20 seconds

step 9

wash gently for a few seconds, blot dry with bibulous paper, and air dry

step 10

examine slide under oil immersion

step 11

dispose gram stain waste in the beakers