Dynamics of acute Montipora white syndrome: bacterial communities of healthy and diseased M. capitata colonies during and after a disease outbreak.

Coral diseases contribute to the decline of coral reefs globally and threaten the health and future of coral reef communities. Acute Montipora white syndrome (aMWS) is a tissue loss disease that has led to the mortality of hundreds of Montipora capitata colonies in Kane'ohe Bay, Hawai'i in recent years. This study describes the analysis of coral-associated bacterial communities using high-throughput sequencing generated by the PacBio RSII platform. Samples from three health states of M. capitata (healthy, healthy-diseased and diseased) were collected during an ongoing aMWS outbreak and a non-outbreak period and the bacterial communities were identified to determine whether a shift in community structure had occurred between the two periods. The bacterial communities associated with outbreak and non-outbreak samples were significantly different, and one major driver was a high abundance of operational taxonomic units (OTUs) identified as Escherichia spp. in the outbreak sequences. In silico bacterial source tracking suggested this OTU was likely from sewage contamination of livestock, rather than human, origin. The most abundant coliform OTU was a culturable E. fergusonii isolate, strain OCN300, however, it did not induce disease signs on healthy M. capitata colonies when used in laboratory infection trials. In addition, screening of the sequencing output found that the most abundant OTUs corresponded to previously described M. capitata pathogens. The synergistic combination of known coral pathogens, sewage contaminants and other stressors, such as fluctuating seawater temperatures and bacterial pathogens, have the potential to escalate the deterioration of coral reef ecosystems.

Pseudoalteromonas piratica sp. nov., a budding, prosthecate bacterium from diseased Montipora capitata, and emended description of the genus Pseudoalteromonas.

A Gram-stain-negative, motile, rod-shaped bacterium designated OCN003T was cultivated from mucus taken from a diseased colony of the coral Montipora capitata in Kane'ohe Bay, O'ahu, Hawai'i. Colonies of OCN003T were pale yellow, 1-3 mm in diameter, convex, smooth and entire. The strain was heterotrophic, strictly aerobic and strictly halophilic. Cells of OCN003T produced buds on peritrichous prosthecae. Growth occurred within the pH range of 5.5 to 10, and the temperature range of 14 to 39 °C. Major fatty acids were 16 : 1ω7c, 16 : 0, 18 : 1ω7c, 17 : 1ω8c, 12 : 0 3-OH and 17 : 0. Phylogenetic analysis of 1399 nucleotides of the 16S rRNA gene nucleotide sequence and a multi-locus sequence analysis of three genes placed OCN003T in the genus Pseudoalteromonas and indicated that the nearest relatives described are Pseudoalteromonas spongiae, P. luteoviolacea, P. ruthenica and P. phenolica(97-99 % sequence identity). The DNA G+C content of the strain's genome was 40.0 mol%. Based on in silico DNA-DNA hybridization and phenotypic differences from related type strains, we propose that OCN003T represents the type strain of a novel species in the genus Pseudoalteromonas, proposed as Pseudoalteromonas piratica sp. nov. OCN003T (=CCOS1042T=CIP 111189T). An emended description of the genus Pseudoalteromonas is presented.