Lab 2: The Desalination Challenge Thru Inoculation Effect (microbial Management)
Objective: Following discussions on soil contamination students begin building a closed ecosystem using their regolith simulant and cyanobacteria amendment for soil. If we had true regolith it would be contaminated with toxic perchlorates that our bacteria would not just be an organic building block but also work to neutralize the perchlorate that are damaging to plant growth. The criteria of desalination is a goal for success; however, there is no contaminant in the simulate we will be using. While they don't eat the salt, growing cyanobacteria can actually improve salty (saline) soils by adding organic matter, fixing nitrogen, and improving soil structure, which helps lower the overall stress of the salt on plants. This means the students will be learning to overcome the constraints of Martian soil without engaging in the process. Also, by adding a nitrogen-fixing bacteria like cyanobacteria student engage with microscopic living things that demonstrate how microbes function in the nutrient cycle by fixing nitrogen.
- Oklahoma Standard: MS.ETS1.1 (Define the criteria and constraints of a design problem).
- Oklahoma Standard: 8.LS1.5 (Construct a scientific explanation for how environmental factors influence growth).
- Procedure:
- Grouping: Students working in groups to Construct their Martian stimulated greenhouse in a jar using Sterile Simulant.
- Each team will need a sterilized jar and sterilized Martian stimulus. For this lab dry heat sterilization will be adequate. In a lab or hot air oven you are required to reach a temperature is 160°C to 180°C (320°F to 356°F) and maintain it for 60 to 120 minutes. I will prep this ahead of time Using the student prepared stimulated regolith in canning jars with the appropriate lid to create a seal as the jar cools.
- Cautions given for the experiment: each team will need to be careful as to minimize the amount of contaminants introduced to their jars throughout this year long experiment. - This is an excellent opportunity to talk to students about contamination and vectors.
- Watering: the students will now decide as a team how much water their soil can hold and record their initial water investment. They will then measure out the appropriate amount of water and place it in a covered container.
- Soil inoculation: At this time, I will give each student a premeasured amount of beneficial starter bacteria. Once everyone has their bacteria and their initial water investment, they will carefully open their jar and place the water and bacteria in the jar closing it again.
- Monitoring and logging: this will be the first long-term observation and could take week to months. During this time students should be logging observations and adding water if necessary. Students may take the jar periodically to spread moisture and bacteria however they are not to be opening the jar. Observations can be done daily or weekly depending on our time and students will be observing the weight of the jar as well as any visual changes.
- Scientific Inquiry:
- How does the addition of Cyanobacteria increase water retention IE when you tip your jar does water run out of the regolith?
- Do you think you have achieved creating soil and are you ready to plant?
- Working at your fellow students’ jars are you doing something different that is beneficial or negative and how could you improve the growth of your bacteria?
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