Transcript Inoculating a Petri Dish

Inoculating a Petri Dish
Procedure for Dry and Wet Swab
Label
Divide the Petri dish into sections-if
applicable-and label the bottom (agar
side) of the dish using permanent
marker
 Label along the outer edges of the dish
so the labels do not interfere with
viewing the organisms

Inoculate
Use sterile cotton swab to wipe the
surface or liquid being tested. Do not let
anything touch the sterile tip
 If you use a control plate, new
untouched, cotton swabs are good to
use

For a Dry Surface
Wet the swab by dipping to in sterile
water. Then wring out by wiping it
against the inside of the container
 If the swab is too wet, the liquid will flow
into other sections and microbial
colonies will run into each other.
 Swab the dry surface

For a Liquid
Dip sterile swab into liquid and wipe it
against the inside of the container
 Inoculate the nutrient agar using a back
and forth motion covering the entire
area of the section or plate. Do not
swab to close to dividing lines for the
next section

Tape
Place cover on inoculated Petri dish and
seal with parafilm-narrow strip,
stretched around outside edge of
covered dish
 Can use masking tape as well-just
make sure it is sealed-dangerous
bacteria!
 Incubator set at 95 º
