Poster Presentation Australian Microbial Ecology 2017

The inner workings of the outer surface: mucosal barrier bacterial assemblages as indicators of changing health status in yellowtail kingfish, Seriola lalandi. (#111)

Thibault PRA Legrand 1 2 , Sarah R Catalano 1 , Andrew PA Oxley 1
  1. SARDI Aquatic Sciences, West Beach, SA, Australia
  2. School of Biological Sciences, Flinders University, Adelaide, SA, Australia

The mucosal surfaces and associated microbiota of fish provide the first line of defence against potential pathogens. We assessed whether the outer-surface bacterial communities reflect a change in gut health status of Yellowtail Kingfish (Seriola lalandi). Active bacterial assemblages were surveyed from swabs of skin and gills by constructing Illumina 16S rRNA amplicon libraries. Proteobacteria and Bacteroidetes were predominant in both skin and gills, with enrichment of key b-proteobacteria in the gills (Nitrosomonadales and Ferrovales). Fish exhibiting early stage chronic lymphocytic enteritis comprised markedly different global bacterial assemblages compared to those deemed healthy and exhibiting late stages of disease. This corresponded to an overall loss of diversity and enrichment of Proteobacteria and Actinobacteria, particularly in the gills. In contrast, bacterial assemblages of fish with late stage disease were generally similar to those of healthy individuals, though with some distinct taxa. This likely reflects changes in immune states and/or barrier systems during early onset of the disease as marked by physical changes in the underlying epithelia. This study represents the first to investigate the microbiota of the outer mucosal surfaces of fish in response to underlying chronic gut enteritis, revealing potential biomarkers for assessing fish health in commercial aquaculture systems.