The GenBank accession numbers for the SXT gene sequences of Marinomonas sp. strain AN44, Vibrio fortis strain AN60, and V. cholerae strain SG24, respectively, are JQ900625, JQ900626, and JQ970522. Microbial communities associated with coral mucus are taxonomically and functionally diverse (Bourne & Munn, 2005; RAD001 in vivo Ritchie, 2006). In this study, 18 bacterial strains were isolated

from the coral F. echinata. Identification of the strains by 16S rRNA gene sequence analysis revealed that all the strains belong to the five taxa of the class Gammaproteobacteria. Among them, majority of the strains were assigned to the Vibrio core group. All the strains were closely related to previously described bacterial species, with a similarity of more than 97% with the first 1300 bp of the 16S rRNA gene (Table 1). Earlier studies revealed that the heterotrophic bacterial community of the mucus of the stony coral Fungia scutaria from the Red Sea is composed mainly of the bacterial groups Alphaproteobacteria,

Gammaproteobacteria, and Actinobacteria (Lampert et al., 2006). Rohwer et al. (2002) reported that bacterial associations with the corals are species specific, even when the corals are physically close to one another. Moreover, bacterial community described in the tissue of reef coral Pocillopora damicornis was dominated by Gammaproteobacteria, while the mucus of the coral was dominated by Alphaproteobacteria (Bourne & Munn, 2005). In contrast, we compared the composition of bacteria of the coral F. echinata from Andaman Sea and detected only the members of the GSK-3 inhibitor Gammaproteobacteria. The PCR results showed the presence of SXT integrase-encoding gene in Amino acid two strains identified as Marinomonas sp. (strain

AN44) and V. fortis (strain AN60), with an expected amplicon size of ∼ 500 bp, whereas the SXT Hotspot IV-encoding gene was absent in both the strains (Fig. 1a). This might be due to the lack of primer specificity or a mutation in that specific gene. Sequencing of the PCR-amplified SXT integrase from the strains AN44 and AN60 identified open reading frames with identities to genes that encode SXT integrase reported from other bacteria. Moreover, strain AN44 was positive in dot-blot hybridization, suggesting that it carried SXT Hotspot IV gene. Interestingly, strain AN60 was negative (Fig. 1b). Based on these results, we investigated relationships, if any, in the SXT integrase gene sequences and constructed a neighbor-joining phylogenetic tree (Fig. 2) using SXT gene sequences of different organisms. Phylogenetic tree exhibited clustering with the members of Gammaproteobacteria. Comparison of the derivative amino acid sequence of these genes with those in the databases revealed high degree of similarity with SXT integrase reported from different bacteria.