CULTURED SHRIMP HEALTH STATUS IS ASSOCIATED WITH THE COMPOSITION OF AQUATIC AND INTESTINAL BACTERIAL COMMUNITIES  

It is widely accepted that the microbes in pond water and shrimp intestine are related to disease outbreaks in shrimp. However, we know little of how the microbial community in water or intestine relate to the health status of cultured shrimp due to the limits of traditional microbial methods. Here, we used next generation sequencing techniques to investigate the aquatic and intestinal bacterial communities from shrimp-culturing ponds.

We tracked the changes of bacterioplankton communities in 6 shrimp ponds (2,000 m² for each) during a period of 43 days. We found that the community composition changed over time, with greater similarities between samples from consecutive sampling points. The variations of the bacterial communities from different ponds shared similar successional trajectories, suggesting that bacterial temporal dynamics are predictable to a certain extent. We also compared the bacterioplankton composition of ponds with healthy shrimp populations (PHS) with that of ponds with diseased shrimp populations (PDS; n=5) and found that the bacterial communities in PDS were markedly distinct (P < 0.05) from those of PHS. The results also showed that the bacterioplanktonic community dramatically deviated from the defined trend when disease occurred. We created a model to identify indicators that discriminated ponds with diseased shrimp populations from those with healthy shrimp populations. An improved logistic regression model additionally revealed that the occurrences of 13 indicator families could be predictive of the shrimp health status with a high degree of accuracy (>79 %).

Changes in shrimp intestinal bacterial communities occurred in parallel with changes in disease severity, reflecting the transition from a healthy state to a diseased one. This pattern was further evidenced by 38 bacterial families that were significantly different in abundance between healthy and diseased shrimps. In addition, with some bacterial families, the patterns of increase or decrease were consistent with their known function as disease-causing agents.

Overall, these findings might be of importance to the managing of water and intestinal microbiota, exploration of new taxon as more effective probiotics, and thus to the final goal of controlling disease before an outbreak event.