What are cyanobacteria?

Introduction

At this point, you’ve probably heard this a thousand times, but our world is rapidly changing, temperatures are rising, and natural resources are thinning by the day. Right now, the focus is shifting from land resources to ocean ones. The sea is currently serving as a food provider, a mineral and water resource, and an energy producer. As you can imagine, this is all taking a great strain on our planet’s bodies of water—oceans, lakes, and rivers alike. And perhaps the Earth would have been able to take it, had we not been polluting the planet at the same time.
At some point in our lives, we’ve all seen news headlines along the lines of: Beach closed due to oil spill, Oil spill renews call for drilling ban, Ship leaks oil in a protected area or, Oil spill threatens marine life. [1] Petroleum spills, both on land and in the sea, are devastating for the ecosystems, and we are proposing a solution that can tackle this issue.

Lake pollution

For our project we chose to work with freshwater cyanobacteria and decided to focus mainly on lake water pollution due to a couple of reasons. The first time we were swayed in this direction was when we took a look at how a watershed works. A watershed refers to a portion of land that drains to a common point, like a river, a creek, or a lake. Meaning water from all the cities, forests, farms etc. in an area eventually reaches a single body of water. Smaller watersheds drain into larger ones and so on until water eventually reaches the ocean. [2] In other words, pollution from upstream can eventually reach the sea pretty easily. So, if we were going to tackle water pollution we figured, why not start at the source? A second reason for our choice consisted mainly of the fact that lake water pollution is an issue that is less talked about, but in our opinion, it is just as important. In the end, we chose to focus on oil spills in lakes.
According to the Environmental Protection Agency, over 90 million liters of oil end up in the trash or in water bodies each year. This type of pollution can lead to high levels of phosphates and nitrates, which in turn can cause algae blooms. We found a way to make these naturally occurring blooms fight the very pollution that is causing their appearance. You can find more about this in the Our Solution section, but first let’s take a look at lake pollution in our country.

Figure 1: A watershed Inspired from source: Mid-America Regional Council Reproduced by our team.

Lake pollution in Romania

Our country is located in the south-eastern part of Europe and due to its varied terrain filled with mountains, hills, and plains, it has around 3.500 lakes. [3] One of them is actually located in our city, called Lake Noua. This lake is a popular spot among our city’s habitants, whether they want to have a relaxing picnic, spend a couple hours in a boat, or hike one of the many trails that start near the lake. All the members in our team have been there at least a couple dozen times.
Due to its popularity, there can be many causes for oil spills, such as the fuel used in generators for the numerous kiosks around, or for the ATVs sometimes seen on the hiking trails, not to mention from all the cars parked around the lake. In the last ten years, we’ve noticed a considerable decrease in fish populations, and instead a rapid increase in algae and in trash floating around the lake. Since this place is important to all of us in some way or another, we couldn’t not do something about it.

Our solution

Background information

Cyanobacteria, also called blue-green algae, are one of the first organisms on Earth. These primitive bacteria produce oxygen during photosynthesis, as a result of fixing carbon dioxide dissolved in water. [4] Chloroplasts, which are responsible for photosynthesis, are fragments that evolved from cyanobacteria. Various bioreactor systems have been proposed in which algae are used to treat polluted water, while the harvested algal biomass can be used for industrial applications such as biofuel and fertilizer production. For this reason, we want to further explore the possibility of using cyanobacteria as a bioremediation tool.

Goal

As cyanobacteria has a rapid multiplication rate, it can form blooms that, in some cases, release toxic compounds such as cyanotoxins. We aim to engineer cyanobacteria in order to make use of these otherwise harmful blooms. Our modified microorganisms will degrade petroleum. The first step however before developing this, is studying cyanobacteria from a variety of perspectives to better understand their characteristics. For this reason, we determined features such as their growth pattern, multiplication rate and quantity of photosynthetic pigments. Moreover, we analysed them under variable conditions such as different temperatures, pH levels and nutrients to better fit a real-life environment, which provides more accurate information about bacteria development. Results were correlated with one another to characterize these organisms.

Figure 2: The cyanobacteria study process

Degrading petroleum: a synthetic biology application

Alcanivorax borkumensis is a bacteria found in polluted waters, which has the capacity to break down petroleum, metabolizing it and converting it into non-toxic compounds and water, which are then released back into nature. [5] We want to use the property of this bacteria and give it to cyanobacteria. There are several genes involved in oil degradation, but we are mainly interested into two of them: alkB1 and alkS, which have the functions of first attaching the bacteria to the petroleum and after that degrading it. AlkB1 catalyzes the hydroxylation of n-alkanes and fatty acids in the presence of a NADH-rubredoxin reductase and rubredoxin. AlkS activates the expression of AlkB1 in the presence of alkanes. These genes will be introduced into a plasmid containing a medium strength ribosomal binding site, which has a high rate of protein production.

Figure 3: Alkanivorax brokumesis breaking down petroleum. Inspiration from source: https://microbewiki.kenyon.edu/index.php/Oil-Eating_Bacteria:_A_Tool_for_Bioremediation Reproduced by our team.

References

[1] Oil spills. (n.d.). The New York Times.
[2] Oil and Water Don’t Mix. (n.d.).
[3] Climate Change Post. (2023) Fresh water sources in Romania:
[4] Kasting, J. F., & Siefert, J. L. (2002). Life and the evolution of Earth's atmosphere. Science (New York, N.Y.), 296(5570), 1066–1068.
[5] Oil-Eating Bacteria: A Tool for Bioremediation - microbewiki. (n.d.).