Identification of culturable bacteria isolated from sponges affected in the 2016 massive die-off at the Flower Garden Banks National Marine Sanctuary (FGBNMS)

This project was conducted to identify culturable bacteria isolated from sponges affected in the 2016 massive die-off at the Flower Garden Banks National Marine Sanctuary (FGBNMS). The FGBNMS was considered a healthy reef system until sport divers reported on July 25th 2016 green, hazy water with huge patches of white mats on corals, sponges, other vertebrates and dead animals littering the bottom of East Flower Garden Bank. To help elucidate the root cause of this event, affected and unaffected sponge samples of Agelas clathrodes and Xestospongia muta sponges from East bank were examined for their associated microbial communities using culture-dependent methods. MALDI – TOF – MS and 16S rDNA sequencing were used to identify representative isolates. MALDI – TOF – MS and 16S rDNA sequencing analysis showed the presence of Bacillus firmus, Pseudovibrio spp., Halanaerobium spp., Microbulbifer variabilis, and Microbulbifer spp. in unaffected samples. Bacillus firmus could help sponges by nitrogen fixation and producing secondary metabolites that protects sponges from predators and Halanaerobium sehlinense is fermentative bacteria. The role of Halanaerobium sehlinense in sponges is not yet clear. Affected samples showed the presence of Vibrio spp. and Halanaerobium sehlinense. Vibrio spp. which occurs naturally in sea water as opportunistic pathogenic bacteria exhibits stronger proteolytic (caseinase), phospholipase and hemolytic activities. These potential pathogens may have contributed into massive die-off at East bank of FGBNMS.