ERA-NET: BlueBio - Microalgae Microbiomes - A natural source for the prevention and treatment of diseases in aquaculture (AquaHealth)

The AquaHealth project studied the natural synergy of microalgae and their associated microbial consortia to discover, develop, and validate novel bioactive and prebiotic compounds for sustainable use in preventing and treating disease in land-based aquaculture systems. SINTEF, Dept. Biotechnology and Nanomedicine participated in this project based on its high competences in general and molecular microbiology, functional metagenomics, biofilm studies, and high throughput bioactivity screening. In the second reporting period from October 2020 to September 2021, the focus of SINTEF in the AquaHealth project was on developing assays for testing the biofilm inhibition efficacy of microalgae material produced by other partners. A high-throughput microwell and a flow-based biofilm assay were developed with selected strains of the fish pathogens Yersinia ruckeri and Flavobacterium psychrophilum. Initial experiments with microalgae material were performed, with results corresponding to the results obtained by partners at the University of Hamburg, using different assays. The developed assays were used for further search of microalgae-associated microorganisms and compounds produced by these with effects on growth and biofilm formation of the pathogens. SINTEF also started sequencing analyses of the bacterial microbiomes in algae material produced at the Technical University of Hamburg, as well as sequence mining for enzymes and other active compounds in algae/bacteria microbiome data provided by the University of Hamburg. Regular meetings between SINTEF staff and staff at the two Universities in Hamburg and the University of Aalborg ensured close collaboration in Work packages 2, 3 and 4. Communication with all partners was maintained through monthly online progress meetings and internal status reporting. From October 2021 to September 2022, SINTEF finalized the method development, and the HTS and flow-based biofilm assays were used to analyse samples from the other partners. The model organisms that can be tested in these assays include the fish pathogens Yersinia ruckeri, Flavobacterium psychrophilum, Edwardsiella anguillarum, and Aeromonas salmonicida. Considerable work was also done to establish a protocol for testing anti-viral effect of biomass and bioactive compounds from microalgae and their associated microbiomes. The virus protocol includes CHSE fish cell lines from salmon and infectious pancreatic necrosis virus (IPNV). The virus assay was used further for testing anti-viral effect of biomass and compounds from microalgae. One promising enzyme with antibacterial effect was identified by the University of Hamburg, and this was tested by SINTEF with all established protocols. Sequence analyses of algae/bacterial microbiomes, and sequence mining for enzymes and other active compounds in algae/bacteria microbiomes data for antibacterial, antifungal, and antiviral effects was ongoing. SINTEF staff attended the midterm meeting at Aalborg University and also hosted a project meeting in Trondheim in June 2022. In the last reporting period from October 2022 to September 2023, SINTEF used all the methods established in the project to finalize the testing of bioactive compounds identified from microalgae and their associated microbiomes by the University of Hamburg. Several compounds were characterized with good biofilm inhibition property against important fish pathogens, and no cell toxicity of the compounds were found. Results have been submitted for publication. Sequence analyses for monitoring microalgae-associated microbial communities as well as contamination during up-scaled production of algae biomass were finalized. Sequence mining for enzymes and other active compounds in algae/microbiomes genome data with potential antibacterial, antifungal, and antiviral effects was performed using sequence mining tools which were advanced through the project. In summary, AquaHealth delivered both potential bioactive candidates and infrastructure to efficiently search for novel bioactive compounds in the future and to test their effect. SINTEF staff attended the final meeting at the Technical University of Hamburg in March 2023 where all results were shared and discussed. The project ended by August 31st, 2023.

The AquaHealth project's focus on exploring microalgae and their microbiomes for disease prevention and treatment in aquaculture aligns with the growing need for sustainable solutions in the industry. The project's findings contribute to a positive development of sustainable land-based aquaculture, ensuring high-quality food supply while minimizing environmental impact and establishing infrastructure for future bioactive compound exploration. By identifying and characterizing bioactive compounds derived from microalgae, the project offers a natural and eco-friendly alternative to conventional disease treatments, such as antibiotics. This can help address the issue of multi-resistant pathogens and promote more sustainable practices in aquaculture. The project not only delivered potential bioactive candidates but also developed the infrastructure to efficiently search for novel bioactive compounds in the future and to test their effects. The cultivation process was successfully scaled up for two promising microalgae strains, Tetradesmus obliquus and Chlorella sorokiniana, using different indoor and outdoor cultivation systems. An efficient downstream processing method was developed, including cell separation, cell lysis, and dehydration, to facilitate the extraction of bioactive molecules. These advancements pave the way for the future commercial application of bioactive compounds derived from microalgae and their microbiomes in aquaculture. The project conducted comprehensive assessments of the potential benefits of dietary microalgae on rainbow trout, considering growth performance, blood metabolites, and intestinal microbiota. These evaluations provide valuable insights into the use of microalgae as a dietary supplement in aquaculture. To assess the uncertainty and the scope of possibilities of the industrial synergy between microalgae and fish aquaculture, a thorough ex-ante LCA of the AquaHealth project was conducted by modelling the distinct aspects of the technology from microalgae to fish farming and propagating the various forms of uncertainty. The AquaHealth project benefits from a transnational nature, with partners from Germany, Norway, and Denmark, and the multidisciplinarity has provided an added value to the project, being effective and productive. Stakeholders and the public were involved to promote sustainable aquaculture.

Aquaculture is one of the fastest growing food sectors in the world. In order to guarantee continuous, efficient and sustainable production and to safeguard the growth of this important sector, its protection from biological threats is crucial. Within the AquaHealth project, an international consortium of highly experienced partners will assemble and apply an advanced 'omics toolbox on the natural synergy of microalgae and microbial consortia to discover and validate novel bioactive and prebiotic compounds for sustainable use in preventing and treating disease in land-based aquaculture systems. Targeted classes include biofilm and microbial pathogens inhibiting enzymes, peptides and small molecules, as well as antiviral natural products such as reverse-transcriptase inhibitors. The AquaHealth project will deliver fundamental new insight into microalgae and their associated microbiomes. Integrated 'omics approaches and further, sequence- and function-based screening in search for new bioactive and prebiotic candidate molecules will be applied. The cultivation process for selected strains and consortia producing promising targets of interest will be scaled up to pilot scale and appropriate downstream processing developed and applied in order to obtain the valuable candidates for detailed characterization and testing. Economic, environmental and social impacts of novel product candidates will be assessed, as well as routes towards commercialization of identified biomolecules and technologies. Overall, the AquaHealth project will contribute significantly to a positive development of sustainable land-based aquaculture, securing high quality food supply for world's growing population while simultaneously reducing environmental impact.