Poster Australian Marine Sciences Association 2022

Spiroplasma-Related Symbionts of CoTS: Genome Insights into Their Potential Role in CoTS Control (#518)

Patrick W Laffy 1 2 , Brett K Baillie 1 , Lone Hoj 1 2
  1. Australian Institute of Marine Science, Townsville MC, QLD, Australia
  2. AIMS@JCU, James Cook University, Townsville, Queensland 4811, Australia

Spiroplasma (Class Mollicutes, Order Entomoplasmatales, Family Spiroplasmataceae) is the dominant bacterium (>97% of sequence reads) in CoTS testes and is also present in the more variable microbiomes of CoTS ovaries and pyloric caeca (Høj et al., 2018). Studies of related bacterial symbionts in other systems, have demonstrated a direct link between symbiont proliferation and host lipid availability (Herren et al., 2014). If a similar relationship exists between Spiroplasma and COTS nutritional status or gonad maturity, then the symbiont could represent a unique vector for delivery of transgenes (e.g. toxin genes or dsRNA for gene silencing) to CoTS. Size fractionated enrichment cultures from COTS testes underwent genomic sequencing, assembly and binning, and the dominant microbe was confirmed as belonging to the genus Spiroplasma. Comparative analysis with other available Spiroplasma genomes showed a reduced genome size, suggestive of an obligate symbiotic lifestyle. Interestingly, a Spiroplasma previously identified as an obligate symbiont within the hindgut of a sea cucumber collected within the Mariana Trench (He et al. 2018), had a similar genome size and protein composition, suggesting a shared role within their respective marine invertebrate hosts. An analysis of their metabolic capacity and other genes relevant for the CoTS symbiosis will be presented.