Welcome to our ongoing series highlighting our Aquaponics Curriculum!
Over the coming weeks, we will be posting a series of articles covering the basics of each Curriculum Topic. Today, we are covering Topic 2, Lesson 1, Types of bacteria in Aquaponics. Each of these blog posts is aimed to give an overview of the subject and provide one or more critical thinking questions. You can find our first post in this series here. Enjoy!
Bacteria are microorganisms that can have many different shapes (rods, spheres, spirals and amorphous shapes). Bacteria are some of the oldest organisms on Earth. Bacteria are virtually found everywhere. Bacteria form several types of relationships with animals, plants, fungi and other organisms. Symbiosis happens when two organisms “live together.” When the relationship benefits both organisms, this is called mutualism. Commensalism is the relationship when only one organism benefits and the other organism is unaffected. Parasitism happens when one organism, the parasite, benefits and the other organism, the host, is adversely affected.
Although bacteria are microscopic, they play a large role in any ecosystem. For example, in the human body, millions of bacteria can be found in the gut. Mostof these bacteria help humans absorb a myriad of compounds that the body cannot digest. However there are some bacteria that cause disease in animals and plants. Salmonella causes a common bacterial infection in humans an other animals from the ingestion of contaminated foods.
In aquaponics, two genera of bacteria form a mutual relationship with the fish and the plants. Nitrifying bacteria, Nitrosomonas and Nitrobacter are important microorganisms that help keep an aquaponics system in balance. Nitrosomonas sp. converts ammonia to nitrites and Nitrobacter sp. converts nitrites to nitrates.
Because ammonia and nitrites are toxic to fish in minimal amounts, Nitrosomonas sp. and Nitrobacter sp. directly benefit the fish. The fish and Nitrosomonas sp. have a mutual relationship. Nitrobacter sp. and the fish also have a mutual relationship. However, the relationship between Nitrobacter sp. and the fish is more indirect and requires the commensalistic relationship between Nitrosomonas sp. and Nitrobacter sp. Furthermore, because nitrates are a form of nitrogen that plants can absorb, the plants have a mutual commensalistic relationship with the bacteria and fish.
In the next section, these relationships will be expanded upon. The concept of converting nitrogen into a less toxic form for fish and a useful form for plants is very important in aquaponics. The population of bacteria, fish and plants live in a symbiotic relationship and if one population increases or decreases, another population can be affected. For example, if the population of the fish increases, the bacterial populations will increase and the plants need to compensate for the increase of nitrates or additional plants should be added. If the increase in nitrates is not mitigated, the EC of the nutrient solution may dramatically increase.
Critical Thinking Question:
What would happen if there was too much Nitrosomonas in an Aquaponics system?