Characterising the intestinal microbiome of Australian aquacultured abalone

Abstract

Abalone are marine molluscs that are highly prized seafood delicacies. Australia produces more than 1,000 metric tonnes of abalone from aquaculture. Abalone aquaculture research priorities are to improve the growth rates and reduce the mortalities of abalone in aquaculture. Currently, little is known about the microbial communities associated with Australian abalone aquaculture; however, pathogens are associated with high mortality rates in the summer months. By utilising the 16S rRNA gene and high-throughput sequencing, the broad aim of this thesis was to characterise the microbiomes of Australian aquacultured abalone. This objective was undertaken by exploring the microbiome of abalone in early-life stage development, at optimum growth temperature, and when exposed to chronic temperature stress. Microbiomes colonise the digestive tract of animals, prime the gut for food digestion, and aid in immune system development. Abalone microbiome diversity is impacted by season, temperature, diet, and age. In addition, Psychrilyobacter, Vibrio, and Mycoplasma are dominant community members of juvenile and mature greenlip abalone. This indicates that the abalone digestive tract is a niche environment, in which these genera have an important role. Vibrio spp. are important community members that colonise and persist in the digestive tract of abalone throughout development and growth in aquaculture. In particular, V. halioticoli is a known symbiont in abalone from Japan, France, South Africa, and now Australia, with a putative role in abalone energy metabolism. This thesis provides the framework for future investigation into the microbiomes of aquacultured abalone and completements nutritional research. There is scope for the development of prebiotic or probiotic diets in abalone aquaculture that enhance the survival and feeding rates of abalone and promote the stability of the digestive tract flora.