Chinese mitten crab (CMC, Eriocheir sinensis) is an economically valuable species in South-East Asia that has been widely farmed in China. Characterization of the intestinal bacterial diversity of CMCwill provide insights into the aquaculturing of CMCs. Based on the analysis of cloned 16S rRNA genes from culture-independent CMC gut bacteria, 124 out of 128 differ-ent clones reveal＞95 % nucleotide similarity to the species belonging to the four phyla of Tenericutes, Bacteroidetes, Firmicutes and Proteobacteria; one clone shows 91 % sequence similarity to the member of TM7 (a candidate phylum without cultured representatives). Fluo-rescent in situ hybridization also reveals the abundance ofBacteroidetes in crab intestine. Electron micrographs show that spherical and filamentous bacteria are closely associated with the microvillus brush border of the midgut epithelium and are often inserted into the space between the microvilli using a stalk-like cell appendage. In contrast, the predominant rod-shaped bacteria in the hindgut are tightly attached to the epithelium surface by an unusual pili-like structure. Both 16S rRNA gene denaturing gel gradient electrophoresis and metagen-ome library indicate that the CMCMollicutes group 2 appears to be present in both the midgut and hindgut with no significant difference in abundance. The CMCMollicutes group 1, howev-er, was found mostly in the midgut of CMCs. The CMC gutMollicutes phylotypes appear to bemost closely related toMollicutes symbionts detected in the gut of isopods (Crustacea: Iso-poda). Overall, the results suggest that CMCs harbor diverse, novel and specific gut bacteria, which are likely to live in close relationships with the CMC host
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.