Presence of SXT integrating conjugative element in marine bacteria isolated from the mucus of the coral Fungia echinata from Andaman Sea.

In this study, we characterize 18 cultivable bacteria associated within the mucus of the coral Fungia echinata from Andaman Sea, India. 16S rRNA gene sequence analysis showed that all the 18 strains isolated in this study from the coral mucus belong to the group Gammaproteobacteria and majority of them were identified as Vibrio core group. Our objective was to investigate the presence of the SXT/R391 integrating conjugative elements (ICEs) targeting integrase int(SXT) and SXT Hotspot IV genetic elements in these isolates. SXT/ICE initially reported in Vibrio cholerae contains many antibiotic and heavy metal resistance genes and acts as an effective tool for the horizontal transfer of resistance genes in other bacterial populations. Two of our strains, AN44 and AN60, were resistant to sulfamethoxazole, trimethoprim, chloramphenicol, and streptomycin, in addition to other antibiotics such as neomycin, ampicillin, rifampicin, and tetracycline. Using PCR followed by sequencing, we detected the SXT/ICE in these strains. The SXT integrase genes of AN44 and AN60 had a 99% and 100% identity with V. cholerae serogroup O139 strain SG24. This study provides the first evidence of the presence of SXT/R391 ICEs in Marinomonas sp. strain AN44 (JCM 18476(T) ) and Vibrio fortis strain AN60 (DSM 26067(T) ) isolated from the mucus of the coral F. echinata.