Microbiology Techniques

August 17, 2013

Media Names

Nutrient Agar – NA

Potato Dextrose Agar - PDA

How to hold an Inoculating Loop

Flaming the Loop

Streak Plate

• Streak plating is used to isolate a single type of bacteria.

• This technique spreads out original “parent bacteria” in a sparse pattern that ,after growth, results in individual colonies.

• After incubation, the 4th

quadrant of your plate should have dots.

• These small “dots” are individual colonies, and represent millions of bacteria of the same type.

Streak Plate

* IMPORTANT!!!: Be very gentle when streaking the sample onto the plate. Try not

to make a hole on the surface of the medium with your inoculation loop.

Transfer to tubes

Flaming tubes

Streaking a slant

Transfer

Steps for Transfer of Broth to Broth Hold loop or needle with dominant hand( right ) Flame the loop Hold culture tube in left hand Remove red cap with pinkie of right hand Flame mouth of culture tube Place loop into broth( water) Flame mouth of culture tube and close Open culture tube with broth( should be labeled) Dip loop into new broth and mix Flame mouth of tube and close Flame loop Place to the side of your rack

ASEPTIC PROCECURE FOR MICROBE REMOVAL

http://www.youtube.com/watch?v=0odxJy0nR9s&feature=related

Streaking and flaming

Flame the loop to sterilize it and let cool. Position the plate so that the spot of inoculum is nearest the hand

not holding the loop (the opposite hand). Lift the plate lid with the opposite hand; just enough to get the loop

inside and touch the loop to the inoculum spot. It is often helpful to treat the inoculating loop as if it were a pencil - steadying the loop by resting the heel of the hand against the lab bench.

Move the loop back and forth across the spot and then gradually continue toward the center of the plate as you sweep back and forth. Use a very gentle and even pressure.

When creating each phase, do not worry about keeping each pass across the plate separate from previous ones.

When about 30% of the plate has been covered by the first streaking phase, remove the loop and flame sterilize it.

Repeat the above procedure for the second phase, but this time pick up some inoculum by crossing into the first phase 2-3 times and then not passing into it again.

Repeat as necessary for the third and fourth phases. After streaking the plate, flame sterilize the loop before setting it down.

Measuring Zone of Inhibition

END