Intestinal microbiota of mangrove red snapper (Lutjanus argentimaculatus Forsskål, 1775) reared in sea cages

Using polymerase chain reaction ampli¢cation of 16S rDNA coupled to denaturing gradient gel electrophoresis (DGGE) and sequencing of isolated amplicons, we investigated the microbiota of the intestinal digesta and mucosal surface in mangrove red snapper cultured in a cage aquaculture area in Daya Bay. A total of 14 sequences were characterized by phylogenetic analysis. Among the bacterial species determinated from sequences, the g-Proteobacteria group (64.25%, nine species) dominated absolutely in ¢sh intestines. Others belonged to Spirochaetes (14.3%, two species), Cyanobacteria (14.3%, two species) and Firmicutes (7.15%, one species). However, the bacteria were identi¢ed as uncultured accounting for 28.6% (four species). The apparent bacterial richness (calculated as the numbers of DGGE bands) was signi¢cantly higher in digesta than that in mucosal tissue samples (Po0.05). There existed ¢ve dominant individual populations including one unknown species of Firmicutes, Arthrospira sp.,Vibrio metschnikovii,Vibrio harveyi andVibrio sp. in intestinal digesta, and in contrast, only three dominant individual populations including Vibrio natriegens, V. harveyi and Vibrio sp. in intestinal mucosal surface. The results indicated that the microbiota in intestinal digesta was signi¢cantly diierent from that in mucosal surface.