6 minute read
Multi-disciplinary team from Vilnius University wins prestigious international competition
by Eurofish
per cycle. In a test of meat quality, the Lithuanian shrimp did very well, besting imports. Th e scientists have also studied the issue of space as this could be a constraint in the commercial production of tonnes of shrimp per year. To address this, they developed a shrimp tower RAS that would produce high volumes using much less space. In the next production cycle this new RAS will be stocked to see if it lives up to expectations.
Research follows many different directions
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Shrimp production is however only one part of the research being carried by this wing of the Marine Research Institute. Other directions include developing the brackish RAS technology that is used to produce tilapia and rainbow trout. Th e plan is to grow rainbow trout to 70-100 g and then transfer the fi sh to tanks with salt water to see if they can be grown to the large sizes seen when growing trout in the sea. Th e Lithuanian coastline is only 100 km in length, the water is brackish, and most of the coast is protected, so to prevent pressure on coastal waters, the researchers would like to breed fi sh in RAS systems that use salt water. Th is can either be from the geothermal source, where the water is naturally salty, or by adding marine formulated salt, which is very expensive. Th e geothermal water will also be tested for bioaccumulation of different trace elements to make sure that it is suitable for fi sh farming. Th e point is to experiment with diff erent sources of salt to see which gives the best and most cost-eff ective results, because this would potentially allow the development of an innovative saltwater aquaculture industry in Lithuania based on RAS. Dr Nika is convinced that this is where the future of the sector lies, as demand for high value species is likely to increase with rising prosperity. For potential investors too, the prospect of producing on land should be attractive as obtaining permission is much smoother than if the production were in the sea.
Dr Nika’s team has also started experimenting with aquaponics. Two projects are being carried out, one to install aquaponics systems for small-scale crop and aquaculture farmers and the other at the institute’s laboratory on the Curonian spit, where a greenhouse is used to conduct experiments and to train students. Another area of research is probiotics, benefi cial bacteria that help break down and digest feed and promote a healthy digestive tract. Th e researchers are testing feeds produced by a Lithuanian start-up to recommend feeding regimes and provide information on feed conversion rates. Th is research together with the other directions are all part of the Klaipeda 2030 strategy for blue growth in which aquaculture is one of the priorities.
For more information, contact:
Dr Nerijus Nika Marine Research Institute Klaipeda University
nerijus.nika@apc.ku.lt http://apc.ku.lt/en/
The International Genetically Engineered Machine (iGEM) Foundation is an independent, non-profi t organization dedicated to the advancement of synthetic biology, education, and the development of an open community and collaboration. The foundation runs the iGEM competition, an international contest for students to fi nd solutions to everyday issues using synthetic biology. The competition started as a summer event at the Massachusetts Institute of Technology in 2004 with fi ve teams and has since expanded to over 350 teams from 40 countries.
In 2020 a team from Vilnius University won the event’s undergraduate grand prize for work on detecting, treating, and preventing toxic bacteria from colonising fi sh farms using recirculating aquaculture systems (RAS). Led by Ieva Lingyt , a student at Vilnius University’s Life Sciences Centre, the team comprised 14 members, many of them from the Life Sciences Centre, but some also from the faculty of Mathematics and Informatics, faculty of Chemistry and Geosciences, and other departments. It was the discovery that two bacterial infections, columnariosis and cold water disease, were so toxic to fi sh growing in recirculating aquaculture systems that they could decimate a stock within a couple of weeks if left unchecked, that inspired the team to address the issue. Th e solution took the form of a test, like a pregnancy test, that could identify species of Flavobacterium. Th is genus is responsible for several serious diseases in farmed trout and tools currently used for detection are highly complex and not very cost eff ective.
Time is of the essence when treating disease
Like many pathogens these bacteria normally coexist with the fi sh, but if a change in environmental or other conditions raises the stress levels of the fi sh, their immune systems weaken, and they start displaying symptoms of the disease. Within 24-72 hours of changes in fi sh appearance or behaviour, mortality rates accelerate and can reach over 70% among the infected population. Being able to quickly identify the pathogen is therefore a vital step in preventing the disease from
Members of the Vilnius University team that won the 2020 International Genetically Engineered Machine (iGEM) Foundation undergraduate grand prize for their work on detecting, treating, and preventing certain fi sh diseases in recirculation aquaculture systems.
fl aring out of control. Th e primary goal of the project was to develop a detection kit for fl avobacteria that was effi cient, cost eff ective, robust, and fully portable, as current methods, though sensitive and fairly quick, require special laboratory equipment and samples from live fi sh. In addition to developing the test the group created a software tool that could speed up the whole process of developing tests, making it easier to create tests for other pathogens. Another project output was the design and production of a 3D-printed case to protect the testing strip during its use on a fi sh farm.
Once the pathogen is identified the next step is to treat the infected fish. The team was well aware that generally treatment methods for bacterial infections in fish are to dose the fish with antibiotics. While this stops the infection, over time it also contributes to the evolution of antibiotic-resistant pathogens. To avoid this, it was decided that the treatment strategy should help reduce usage of antibiotics against bacterial fish diseases. The idea behind the treatment was to base it on exolysins which attack the harmful bacteria that form biofilms on the fish gills which prevent the fish from respiring. The exolysins would only work when they sense sufficient concentrations of a molecule that expresses the biofilms. However, Ms Lingyt says much more work is needed before such a treatment strategy can be considered safe and effective.
Prevention based on an oral vaccine to prevent fi sh handling
Th e third leg of the project was to develop a prevention strategy that would stop the disease from breaking out again. Th e obvious way to do this is by vaccinating the fi sh but this calls for physical handling which stresses the fi sh and weakens their immune systems. Th e solution was to develop an orally administered vaccine in the form of a protein embedded in a protective envelope. Th e envelope would allow the protein to survive the harsh environment of the stomach so that it could be released in the midgut where naturally occurring bacteria dissolve the protective membrane and enable the vaccine to be absorbed into the bloodstream. In addition to developing the tools for detection, treatment and elimination, the terms of the competition prescribed the creation of a detailed website (https://2020. igem.org/Team:Vilnius-Lithuania) that described the work the team was doing. Moreover, the team made presentation videos, carried out outreach activities promoting synthetic biology, and interacted with academics, government offi cials, and private companies. For the team members, the months of intense work that went into the project were tough but, thanks to all they learned and experienced, also rewarding. Th at they then went on to win the grand prize was like the icing on the cake.
For more information, contact Ieva Lingyt , ieva.lingyte@gmail. com
