Project 6: Functional diversity of endosymbiotic bacterial communities in marine green algae

Project 6 examines the role of siphonous green seaweeds. These seaweeds are amongst the morphologically most complex algae and also one of the most notorious  invasive species in many parts of the world. Their ecological success has repeatedly been linked to their association with endo- as well as epiphytic bacteria. Indeed, recent studies based on 16S rDNA barcoding revealed rich associated bacterial communities. However, little is known about their functional diversity as well as the principles underlying their assembly.

Based at the University of Ghent in Belgium, this project seeks to address how bacteria contribute to the ecological success of siphonous green algae and whether the competitive potential of invasive species may be at least partly shaped by associated microbes. To do this, we apply a metagenomic approach analyzing the functional diversity of epi- and endophytic bacterial communities associated with native and invasive species of Caulerpa. Our strategy involves sampling natural populations along environmental gradients combined with lab experiments aimed at altering the abiotic conditions of the Caulerpa. Sampling natural populations is facilitated by secondments to DEU (Turkey, Levent Cavas) and CIIMAR-Madeira. Characterization of bacterial communities involves Illumina-based 16S rDNA finger printing, combined with microbiome metagenome and transcriptome sequencing focusing on C. racemosa/cylindracea and C. prolifera.

Kathryn Morrissey has been appointed researcher for project 6. As part of her research, Kathryn investigates bacterial communities associated with Caulerpa species and how these communities change under different abiotic stresses. She also develops and applies DNA-stable isotope probing techniques to label bacteria, providing detailed information about the functional diversity of microorganisms and the role they play in host metabolism.

The aim of this project is to piece together an ecological framework of the essential project-6host-bacteria interactions in this system, therefore leading to better understanding of the highly invasive nature of Caulerpa species.