Studying microbiota - the simple solution to bacterial infectious diseases?

Pelteobagrus fulvidraco, or the yellow catfish, is a freshwater organism that dominates Asian aquaculture industry due to its excellent meat quality. However, it is often severely affected by bacterial infectious diseases which can cause the industry severe losses. The stability of an organism’s intestinal flora is extremely important in the natural resistance of fish to bacterial infections caused by pathogens in the digestive tract.

Wu et al. (2010), investigated the microbiota in the intestinal contents and mucus of P. fulvidraco. We assume (as it is not clearly stated) that the aim of their study was to identify any differences in the two microbiomes, but also to see whether 16S rDNA sequencing could improve on previous, more traditional methods. They reference a few papers who have found that 16S rDNA sequencing provided them with novel sequences when compared to traditional agar cultivation (e.g. Holben et al., 2002), however none have looked at this particular organism.

The results of this study showed that Aeromonads are the most common in the guts – some of which possess virulence factors required to induce disease. However, the most dominant bacterial species belonged to Proteobacteria, which is knowledge consistent with other literature. What is most interesting about their results is that they identified most of the organisms found in the intestinal contents and in the mucus as opportunistic pathogens – this has also been seen in studies relating to human intestinal microbiota (Hand, 2016). By using 16S rDNA sequencing in this study the authors were able to determine that the alimentary microflora of fish is more complex than originally thought.

Overall, this study has resulted in a number of novel discoveries about the composition of the intestinal and mucus microbiota in P. fulvidraco. However, at the beginning of the paper Wu et al., stated that “knowledge about the fish microbiota would help to understand the disturbances…brought about during these disease outbreaks”. The authors do not make a link between what their results show and any further studies possible, which presumably could be quite advantageous to the aquaculture industry, in order to investigate or prevent the outbreaks of disease in farmed communities.

Studied paper

Wu, S., Gao, T., Zheng, Y., Wang, W., Cheng, Y., Wang, G. (2010). Microbial diversity of intestinal contents and mucus in yellow catfish (Pelteobagrus fulvidraco). Aquaculture (303) 1-7.

References

Hand, T. (2016). The Role of the Microbiota in Shaping Infectious Immunity. Trends in Immunology (37), No. 10.

Holben, W. E., Williams, P., Gilbert, M. A., Saarinen, M., Serkilahti, L. K., Apajalahti., J. H. (2002). Phylogenetic analysis of intestinal microflora indicates a novel Mycoplasma phylotype in farmed and wild salmon. Microbial Ecology (44), 175-185.