Sex-bias of core intestinal microbiota in different stocks of Chinese mitten crabs (Eriocheir sinensis)

The differences in intestinal microbiota composition are synergistically shaped by internal and external factors of the host. The core microbiota plays a vital role in maintaining intestinal homeostasis. In this study, we conducted 16S rRNA sequencing analysis to investigate the stability of intestinal microbiota and sex-bias of six stocks of Chinese mitten crabs (105 females; and 110 males). The dominant phyla in all six stocks were Proteobacteria, Tenericutes, Bacteroidetes and Firmicutes; however, their relative abundance differed significantly. Twenty-seven core operational taxonomic units (OTUs), corresponding to 18 genera, were screened. Correlation analysis revealed that OTUs of four stocks in the Yangtze River system play important roles in maintaining the stability of intestinal microbiota. Additionally, the core intestinal microbiota was significantly sex-biased, and the top three genera in terms of relative abundance (Acinetobacter, Vibrio, and Candidatus_Hepatoplasma) were significantly dominant in female crabs. Network structure analysis also confirmed gender differences in the association pattern of intestinal microbiota. The intestinal microbiota of male crabs has a higher degree of functional enrichment. This study provided a theoretical basis for further investigating exploring the shaping effect of gender and geographical factors on the intestinal microbiota of Chinese mitten crabs.