Selecting and characterizing probiotic strains for aquaculture

CREATEC-CV program, funded by IVACE and co-financed with ERDF funds, aims to promote innovative technology-based entrepreneurship, business diversification, economic growth, and the creation of quality jobs within the business fabric of the Valencian Community by supporting the development of small innovative and technology-based companies. This DARWIN project focuses on the development of probiotics intended for aquaculture.


The main objective of the project was the selection, characterization, and production of new probiotic microorganisms for use in aquaculture, specifically to inhibit the growth of pathogenic microorganisms that affect the three main fish species produced in Spain: trout, gilthead seabream, and European seabass.




Fish is considered a particularly important food due to its high protein content and essential nutrients such as polyunsaturated fatty acids, minerals, and vitamins. The increase in global demand for this food necessitates sustainable development in the aquaculture industry.


In this context, the development of diets that include probiotic supplements has great potential and helps reduce the use of antibiotics in this sector. Probiotics are live dietary supplements that have positive health effects, such as aiding the digestive process or stimulating the immune system. Additionally, many probiotics can inhibit the growth of certain pathogenic microorganisms that cause infectious diseases, the main cause of economic losses in aquaculture.


Another challenge caused by the increased demand for these foods is the need to produce a greater amount of raw materials for fish feed. One proposed solution to this problem is the use of agricultural by-products as a source of protein for fish feed, but their digestion can result in the generation of toxic metabolites. An example is saponin, which can cause intestinal enteritis in fish.




The solution proposed by DARWIN for these challenges was to select and characterize probiotic strains for fish through the mass screening of potentially probiotic strains from our microorganism collection. These strains underwent a battery of tests to verify their ability to survive and grow under the environmental conditions they would face in fish farms and in the fish intestines. The project was divided into different phases:

  1. Testing the resistance of probiotic strains to fish farm and intestinal conditions (growth at different temperatures, resistance to salinity, pH, bile, and degradation of saponin).
  2. Detecting the antibacterial activities of probiotic strains against selected fish pathogens (Tenacibaculum maritimum, Yersinia ruckeri, Aeromonas salmonicida, Pseudomonas fluorescens, Vagococcus salmoninarum, and Vibrio harveyi).
  3. Studying the interactions between probiotic strains in co-culture to guide the formulation of the final product and avoid undesired interactions.
  4. Production and lyophilization of the selected probiotics for their subsequent application in fish farms.
  5. Characterization of the microbiota that inhabits international fish farms.



Year of Completion: 2020




The capabilities of withstanding fish farm conditions, their broad-spectrum activity against the battery of pathogens tested in this project, the high production yield, and the high viability of the lyophilized products over time make the selected microorganisms (a strain of Lacticaseibacillus paracasei) very promising for application as probiotics in fish farms.