Microbiology Lab Safety
In this lab, we focused on skills we will be using throughout this course. This lab specifically focused on hand hygiene. We will be dealing with microorganisms that humans tend to interact with, so it is important to learn safety in lab. Even though they are not harmful, safety is always an important skill to have in a lab setting, especially when we are working independently without guidance.
The objectives of this lab were to work with microorganisms in the safe proper way, use the correct experiment equipment and use it in the correct way, and follow instructions to protect us in lab setting.
3. Methods and Materials
(1) 250 mL beaker
1 tsp. sugar
(4) 5 cm. Petri dishes
20 drops deionized water
(4) Sterile transfer pipettes
(4) Sterile cotton swabs
(4) Disposable gloves
10% bleach solution
The method we used to discover the importance of hand hygiene was using four petri dishes with nutrient agar plates to accumulate bacteria from our hands as they were at different stages.
1. Prepare the agar plates: We microwaved the nutrient agar bottle, swirling its contents every 10 seconds until it was completely liquefied. Once it was in full liquid form, we poured about 5 mL into each of the four petri dishes, filling the bottom of the dish. We then placed the lids onto the dishes to allow the agar to solidify, which took approximately an hour. Each petri dish was labeled #1-4
2. Preparing the yeast solution: We measured 230 mL of warm water into the provided 250 mL beaker. We then added 1 tsp. of sugar and the full yeast packet to the beaker. We stirred this mixture together until the ingredients dissolved and it began to froth.
3. Testing the hands: To collect the hands bacteria, we put a glove on our non-dominant hand, added 8-10 drops of the deionized water to the gloved hand and rubbed our two hands together to spread the water over our dominant hand. Once the water covered the hand, we took a cotton swab to the non-gloved hand to collect the bacteria, and then rubbed the cotton swab onto the agar plate. In petri dish #1, a plain, unchanged hand bacterium was collected. Between collecting bacteria, we washed our hands with warm water and hand soap for at least 20 seconds, using the provided hand soap and stop watch. We then repeated the same process as we did for petri dish #1, so for petri dish #2 we collected bacteria of a hand that was just washed. For petri dish #3, instead of deionized water, we added the yeast solution to our hands and collected that bacterium. Petri dish #4 contained bacteria from the yeast solution, but after the hands was just washed. Between each collection of bacteria, we made sure to change gloves and cotton swabs.
4. Letting the petri dishes sit: After we finished collecting bacteria, the lids were placed on the petri dishes and we sealed them with parafilm. They remained in a warm location for several days until I started to see colonies grow. I counted and recorded the number of colonies I saw. Before discarding the petri dishes, I cleaned our the agar with 10% bleach solution and let them incubate for 20 minutes then poured the bleach down the drain with running water.
Table 1: Experiment 1 Colony Growth
Water minus hand washing
Water plus hand washing
Yeast minus hand washing
Yeast plus hand washing
1. What constitutes personal protective equipment? When should personal protective equipment be worn? Why is personal protective equipment important?
Personal protective equipment, commonly referred to as "PPE", is equipment worn to minimize exposure to serious workplace injuries and illnesses. Some examples of personal protective equipment include gloves, safety glasses and shoes, earplugs or muffs, hard hats, etc. This