Marine invertebrates are associated with various microorganisms that play a significant role in their host’s development, nutrition, immunity, and health. These microbial communities can be detected on the animal surface (epibiosis), in the digestive tract, but also in the hemolymph or circulatory fluid. Also known as microbiota, they can produce growth factors and antimicrobial molecules, therefore contributing to the protection of their host against pathogenic infections. Aquatic organisms are generally colonized by microbial communities via water and sediments. Recent studies have shown that the assemblage of benthic animals influence the composition of the environmental microbiome, thus modulating the composition of the microbiome available for absorption.
In this study, we assessed whether inter-species assemblages affect the water and the animal’s microbiota and their survival to vibriosis infection. Microbiota was estimated using Illumina sequencing of the V4 region of the 16S rRNA gene. Different assemblages were experimentally created, including the blue shrimp Penaeus stylirostris, the giant clam Tridacna maxima and the sea cucumber Holothuria scabra. These species were chosen based on recent studies showing the existence in these animals of resident microbial communities (i.e. a core microbiome associated with a variable microbiome that varies according to the physiological conditions of the host, environmental conditions, etc.) but also for their economic interest in New Caledonia and more generally in the Pacific.
After few weeks of living along with other invertebrates, the shrimp microbiota was influenced by the assemblages (Fig. 1) and also impacted by the vibriosis infection. Their immune status was also modulated according to species assemblage and a differentiated response to bacterial infection was observed. The association with giant clams appears to help the blue shrimp cope with vibriosis infection.