Characteristics of intestinal microbiota in male morphotypes of the giant freshwater prawn Macrobrachium rosenbergii

There is a close correlation between intestinal microbiota and development. However, our understanding of the relationship between the intestinal microbial community and phenotypic traits in giant freshwater prawn (GFP), Macrobrachium rosenbergii, remains limited. Here, we explored this association between the gut bacterial com-munity composition and phenotypic traits of male morphotypes of the GFP by using culture-dependent and high-throughput sequencing approaches. The results showed that Lactococcus garvieae was the dominant bacterial species, and accounted for 83.3%, 82.7%, 65.5%, and 40.8% of the total bacteria in the orange claw (OC), small males (SM), blue claw (BC), and old blue claw (OBC) groups, respectively. The relative abundance of the in-testinal bacterial communities in the OBC and SM groups differed significantly from that in the OC and BC groups. We also observed statistically significant associations between gut microbiota and phenotypic traits. Moreover, the results obtained by using the conventional culture method further confirmed that L. garvieae was significantly predominant in all groups and more abundant in the OC and BC groups, suggesting an important role of L. garvieae in GFP development. This finding strongly suggests that the intestinal microbiota of GFP is tightly correlated with the morphotypic differentiation likely owing to its effects on nutrient metabolism in the gut.