Dr. Catarina Moreirinha (University of Aveiro) has presented the results of the Enviphage project in the Phage Therapy World Congress (Paris). Her oral presentation to more than 100 researchers from around the world generated great interest among the attendees. You can access the summary of his presentation at the “Diffusion material ” section.
Catarina Moreirinha, Carla Pereira, Adelaide Almeida. Phage therapy in aquaculture: in vitro and in vivo studies. 2-3 June, 2016. Phage Therapy World Congres, Paris, France.
“The fastest growing food animal-producing sector worldwide is aquaculture, providing about 30 percent of the world seafood supply. However, it often suffers from heavy ﬁnancial losses because of the high mortality caused by bacteria, namely multidrug-resistant bacteria that are easily transmitted through the water and infect a great variety of aquaculture species.
Nowadays, phage therapy is considered a potential viable alternative to antibiotics for inactivation of bacteria in aquaculture systems.
A major concern of bacterial inactivation by phages is the emergence of phage-resistant bacteria, and few is known about the resistance mechanisms that are developed in the presence of phages.
The efficiency of three different phages to inactivate Aeromonas salmonicida was tested in vitro. This bacterium causes furunculosis, a disease characterized by high mortality in aquaculture fish. It was found that all of the three phages (either single or combined in cocktail) decreased the concentration of this bacterium to 4 log.
In vivo experiments with two E. coli phages using cockles in a depuration system with recirculating water showed that approximately 2 log of bacteria were inactivated in artificially contaminated cockles, and approximately 0.6 log in naturally contaminated ones. It was also found that the use of phages during depuration decreased bacteria concentration faster than the use of depuration alone, as to achieve the same bacterial concentration decrease, two more hours were needed if no phage was used.
Regarding the development of bacterial resistance to phages, it was verified that mutant bacteria rapidly recover their susceptibility to the phages and the colonies grow much slower and small than the susceptible bacteria. Taking this into account, infrared spectroscopy was used to assess the spectral modifications of the bacterial cells that developed resistance. It was found that there were great modifications in the protein spectral region, suggesting that surface proteins, that can be phage receptors, are greatly implied in this process.
These results suggest that phage therapy might be the most promising choice to be used in aquaculture fish and during the bivalve depuration to control the transmission of bacteria that can cause economic losses or be harmful to the consumers.”