Symbiotic bacteria within the gut microbiome of various organisms, including fish, provide the host with several functions that improve the immune system. Although the spleen plays an important role in the modulation of immune responses, the role of spleen microbiota in shaping the immune system is unclear. Our study aimed at understanding the relationship between fish health and microbiota composition in the intestine and spleen. Our model organism was the hybrid tilapia (Oreochromis aureus × Oreochromis niloticus). We sampled intestine and spleen from healthy and diseased adult tilapia and determined their microbiota composition by sequencing the 16S rRNA gene. Significant differences were found between the intestine and the spleen microbiota composition of healthy compared to diseased fish as well as between intestines and spleens of fish with the same health condition. The microbiota diversity of healthy fish compared to diseased fish was significantly different as well. In the intestine of healthy fish, Cetobacterium was the most abundant genus while Mycoplasma was the most abundant genus in the spleen. Vibrio was the most abundant genus in the intestine and spleen of diseased fish. Moreover, it seems that there is a co-infection interaction between Vibrio and Aeromonas, which was reflected in the spleen of diseased fish. While Vibrio, Aeromonas and Streptococcus were the probable pathogens in the diseased fish, the role of Mycoplasma as a pathogen of cultured hybrid tilapia remains uncertain. We conclude that the intestine and spleen microbiota composition is strongly related to the health condition of the fish.
Bibliographical noteFunding Information:
The authors would like to thank the fish farms that kindly allow us to use their fish for this research. The authors would like also to thank Ina Natapov and Omer Ben Asher (GIS unit, Ministry of Agriculture and Rural Development, Israel) for the maps that they produced. Our special thanks go to Margarita Smirnov and Dr. Benny Ron from the Central Fish Health Laboratory for their helpful advice and valuable support.
This work was supported by the India-Israel Joint UGC-ISF grant (Grant No. 2728/17) and by the United States-Israel Binational Science Foundation, BSF (Grant No. 2015103).
© 2022, The Author(s).
- Bacterial co-infection
- Hybrid tilapia
- Intensive freshwater aquaculture
- Intestine and spleen microbiota composition
- Pathogenic bacteria
ASJC Scopus subject areas
- Veterinary (miscellaneous)
- Agricultural and Biological Sciences (miscellaneous)
- Animal Science and Zoology
- Microbiology (medical)