Colony Variety
Aseptic Techniques Name ———————–20 ptsObjectives1.- Be aware of where bacteria can be found, and what are the environmental factors that influence the growth of bacteria.2.- Understand the process and importance of labeling and incubating agar plates properly.3.- Learn the aseptic techniques practices necessary to prevent cross-contamination4.- Identify growth of bacteria on the surface of an agar plate, a nutrient broth, and an agar slant.5.- Use colony number estimates to reach conclusions about amount of bacterial growth.6.- Determine the effects of handwashing on bacterial abundance. Determine the effects of bench disinfection on bacterial abundance.7.- Define: pure culture, contamination, aseptic techniques.8.- Know the characteristics of broth medium, bacterial slants, and agar plates.9.- Identify the steps of transferring from broth to broth, slant to slant, and broth to plate.1.- Introduction (4.0 pts.)1.- ( 1 pt.) Explain the following conceptsWhat does the phrase bacteria are ubiquitous means?What is media?2.- ( 1pt.) List two locations in a laboratory where bacteria can be found.List two places, in a laboratory, where bacteria should never be found.3.- (1pt.) The first step in working with any type of medium, is to label it properly prior to use.Why are agar plates always labeled at the bottom?Agar plates are always incubated upside down. Explain why.4.- (1 pt.) Incubation temperatures are always given in degree Celsius. The standard incubation temperature of bacteria isolated from human specimens is:Incubating bacteria, isolated from human specimens, at lower temperatures will slow down their growth. Give the approximate temperature (in degree Celsius) of the following incubators:Room temperature incubator:Refrigerator temperature incubator:2.- Ubiquity Exercise (5.0 pts.)In this exercise bacterial presence was investigated in four different environments: banana, soda can, keyboard, and cash.1.- (0.5 pts.) What implement was used to collect the bacterial samples from the 4 different objects?Name the type of medium used in this exercise to grow the bacteria.2.- (1 pt.) Mention two steps that prevented cross-contamination during this exercise.3 .- (1 pt.) During this exercise, what does it mean to streak a plate?What is a colony? Are all colonies alike?Where was the cotton tip discarded after each use?Do you think that the medium used to dip the cotton tip was sterile? Explain your answer.4.- (1 pt.) ***Take a picture of the results obtained and upload the picture onto your lab report.4.- (continuation) Complete the table below with the results of the exercise. Note in the chartunder Colony variety whether the colonies growing on each plate all look the same, or if there are variations in size, consistency, and color.NUMBER OF COLONIES PER PLATEPLATE LABELAmount of bacteriaColony variety seen/not seen5.- (0.5 pts.) Using the results obtained, explain how handwashing affects bacterial quantity and diversity.6.- (0.5pts.) Using the results obtained, determine which of the 4 objects (soda can, banana, keyboard, and cash) tested had the most amount and variety of bacterial growth. Were the results expected?7.- (0.5pts.) Using the results obtained, explain the effects of ethanol disinfection on the bacterial load and diversity of the lab bench.Is wiping the lab bench with ethanol a method of disinfection, or sterilization? Explain your answer.3.- Aseptic Transfer (3 pts.)1.- ( 1 pt.) The use of aseptic techniques is important in obtaining pure cultures.What are aseptic techniques?What are pure cultures (be specific)?2.- ( 1 pt.) What can happen to a culture if aseptic techniques are not followed?What inoculating tools can be used to transfer microorganisms?3.- (1 pt.) When is the inoculating loop sterilized during a bacterial transfer?When is the mouth of the culture tube passed through the flame during a bacterial transfer?4.- Transfer of E. coli from a broth culture to a sterile broth tube (3 pts.)1.- (1 pts.) Put the steps of bacteria transfer from broth to broth in numerical order. * Note, some steps may be used more than once.
