Affected by COVID-19, we are not allowed to enter the aquarium for functional testing. However, we designed an experimentation and presented it with words and diagrams. Throughout the process, we faced some difficulties such as adapting to different water conditions, choosing other kinds of bacteria, and observing results. Once we finished solving the difficulties, our team has come up with a suitable experimental plan. We believe that our project could be applied in the actual situation and function efficiently.
Experiment design of realistic test
Most fish and plants can only survive in a limited range of water temperature. Thus, it is best to maintain the ideal temperature of aquariums between 25℃ to 27℃. Escherichia coli can survive at a temperature ranging from 4℃ to 45℃. Moreover, E. coli is a facultative anaerobic organism. It is able to survive in an environment where water predominates. In addition to temperature, the salt concentration of seawater is also a factor that may affect the function of our E.coli. A research shows that there were no statistically significant effects of salinity (30.0 and 36.5 psu) in their natural range on the survival of E.coli (Jozić; Šolić, 2017). Therefore, our specifically engineered E.coli can be applied into aquarium and work effectively.
In our interview in Chimelong Ocean Kingdom, one of the interviewees raised a concern in the functionality of our engineered E.coli in both seawater and freshwater. In this case, we collected fresh water and seawater from aquarium and cultivated biofilm in two 50cm*50cm*50cm fish tanks. One from the freshwater aquarium (label A), the other from seawater aquarium (label B). When the biofilm grows to the same condition, we then added 9*10^11num E.coli BL21 into each of the sample. (as seen in figure below).
After adding our engineered E.coli, we chose four time points: one week, two weeks, three weeks, and four weeks to observe the degradation.
Since biofilm can be observed directly by naked eyes, we observed that biofilm can be removed as time increases. After four weeks, our results demonstrated that the biofilm is significantly reduced (more than 50%) in both sample A and B. This indicates that our E.coli has performed effectively in both water samples.
Although our project uses E.coli as the base bacteria. Some may question about the drawbacks on using E.coli. As it may affect the water quality or damage the health of some aquatic organisms. Therefore, in practical applications, among different types of bacteria in the aquarium, we will select the largest number of colony that can be found in the aquarium, followed by genetically modifying that specific bacterial colony to remove biofilm.
Jozić, Slaven & Solic, Mladen. (2017). Effect of Environmental Conditions on Escherichia coli Survival in Seawater. 10.5772/67912.