Project name: Zobellia galactanivorans

Description: Macroalgae contribute substantially to primary production in coastal ecosystems. Their biomass, mainly consisting of polysaccharides, is cycled into the environment by marine heterotrophic bacteria (MHB), using largely uncharacterized mechanisms. In Zobellia galactanivorans, we discovered and characterized the complete catabolic pathway for carrageenans, major cell wall polysaccharides of red macroalgae, providing a model system for carrageenan utilization by MHB. We further demonstrate that carrageenan catabolism relies on a multifaceted carrageenan-induced regulon, including a non-canonical polysaccharide utilization locus (PUL) and several distal genes. The genetic structure of the carrageenan utilization system is well conserved in marine Bacteroidetes, but modified in other MHB phyla. The core system is completed by additional functions which can be assumed by non-orthologous genes in different species. This complex genetic structure is due to multiple evolutionary events including gene duplications and horizontal gene transfers. These results allow for an extension on the definition of bacterial PUL-mediated polysaccharide digestion.Overall design: The RNA-seq transcriptome analysis was performed using Zobellia galactanivorans DsijT strain cultivated in marine minimal medium with D-galactose (D-gal; reference condition), kappa-carrageenan (KC), iota-carrageenan (IC) or 3,6-anhydro-D-galactose (D-AnG), as unique carbon source. Expression values were calculated from three independent biological replicates (A, B and C). Total RNA were extracted, mRNA enriched using the Illumina Ribo-Zero rRNA Removal kit (Bacteria), then RNA-seq libraries were generated with the ScriptSeq V2 kit (Illumina). The sequencing was performed with a NextSeq 500 platform using a single-end 75 bases run.

Data type: Transcriptome or Gene expression

Sample scope: Multiisolate

Relevance: Other

Last updated: 2017-07-11