9 Place the loopful of inoculum into the broth and withdraw the loop
10 Again flame the lip of the tube Replace the cap
11 Removing inoculum from a plate organisms growing on an agar surface in a petri plateSterilize the inoculating loop in the flameLift the lid of the culture plate and stab the loop intothe agar away from any growth to cool the loop
12 Scrape off a small amount of the organisms and closethe lid
14 Inoculating an Agar Slant 1.Label the sterile nutrient agar slant with the source of the culture and yourinitials.2. Sterilize the loop.3. Using appropriate aseptic technique, remove a loopful of broth from the culture tube.4. Insert the loop into the sterile agar slant tube and starting at the base ofthe slant, draw the loop up the slant. Do not penetrate the agar. Sterilizethe loop.5. Incubate the slant at 37o C for hours.6. Observe the slant for growth.
18 microorganisms exist in nature as mixed populations(A mixed culture contains two or more bacterial species )However, to study microorganisms in the lab we must have them in the form of a pure culture
19 assumed to be a pure culture Streak plates allow for the growth of isolated colonies on the surface of theagar. An isolated colony is a colony that is not touching any other colonies and isassumed to be a pure culture.
20 You’re never too old to streak! STREAK PLATE METHOD OF ISOLATIONPurpose of streaking: To obtain pure, isolated colonies.Principle: By spreading a large amount of bacteria over the large surface area of a plate, the amount of bacteria is diluted until individual cells are spread on the surface of the plate. Each individual cell grows into a single colony.You’re never too old to streak!
21 Streak PlateLabel the sterile nutrient agar plate with the source of the culture and your initials.. Sterilize the loop.. Using appropriate aseptic technique, remove a loopful from the mixed culture plate.. Lift the agar plate from the lid and streak about half of the plate. The loop should be parallel to the agar surfaceto prevent digging into the agar
22 Return the plate to the lid. Sterilize the loop Return the plate to the lid. Sterilize the loop. Lift the agar plate and makeone streak into the inoculated portion of the plate. Finish by streakingabout one-fourth of the uninoculated plate
23 Return the plate to the lid. Sterilize the loop Return the plate to the lid. Sterilize the loop. Lift the agar plate and makeone streak into the second inoculated portion of the plate. Finish bystreaking the remaining one-fourth of the uninoculated plateSterilize the loop.
24 Place the plate in a 37o C incubator for 24-48 hours.