Microbial community function in the bleaching disease of the marine macroalgae Delisea pulchra

Abstract

Disease is increasingly viewed as a major factor impacting the health of both natural and cultured populations of marine organisms, including macroalgae. The red macroalga Delisea pulchra suffers from a bleaching disease resulting from host stress and infection by opportunistic bacterial pathogens. However, how pathogens cause the disease and how the entire macro algal-associated community is involved in the process is unclear. Here, we perform a metagenomic analysis of microbial communities associated with diseased and healthy D. pulchra across multiple bleaching events. Analysis of reconstructed 16S rRNA gene sequences showed that bacteria belonging to the families Rhodobacteraceae, Saprospiraceae and Flavobacteriaceae, including bacteria previously implicated in algal bleaching, to be enriched in diseased D. pulchra. Genes with predicted functions related to chemotaxis, motility, oxidative stress response, vitamin biosynthesis and nutrient acquisition were also prevalent in microbiomes of bleached algae, which may have a role in pathogenicity. Reconstruction of genomes that were abundant on bleached samples revealed that no single organism contains all bleaching-enriched functional genes. This observation indicates that potential virulence traits are distributed across multiple bacteria and that the disease in D. pulchra may result from a consortium of opportunistic pathogens, analogous to dysbiotic or polymicrobial diseases.

The effect of the algal microbiome on industrial production of microalgae

“…Algae are also adversely affected by a wide range of bacteria; however, underlying mechanisms remain underexplored. Algae‐associated bacteria belonging to the families Rhodobacteraceae , Saprospiraceae and Flavobacteriaceae have been implicated in bleaching of the seaweed Delisea pulchra (Zozaya‐Valdés et al ., ). Gram‐negative bacteria such as members of the genera Alteromonas , Cytophaga , Flavobacterium , Pseudomonas , Saprospira , Vibrio and Pseudoalteromonas are mainly responsible for rot symptoms (Ashen and Goff, ) and galls on seaweeds (Wang et al ., ).…”

The Pathobiome in Animal and Plant Diseases

“…Bleaching disease in the red alga Delisea pulchra is caused by host stress and invasion by secondary bacterial pathogens from several families (Rhodobacteraceae, Saprospiraceae, and Flavobacteriaceae), but no single bacterial lineage has all bleaching-enriched bacterial genes [39]. A related concept is the distribution between co-infecting lineages of bacteria of 'community-dependent essential genes' required for infection [40].…”

Temporal covariation of epibacterial community and surface metabolome in the Mediterranean seaweed holobiont Taonia atomaria

“…In particular, the Rhodophyta Delisea pulchra has been intensively studied with respect to particular chemically mediated interactions (i.e. quorum sensing modulation via the production of halogenated furanones) between the seaweed and its epibacterial community, including pathogens that can be involved in the temperature-dependent bleaching process (Fernandes et al, 2011;Harder et al, 2012;Zozaya-Valdes et al, 2017). More recently, the role of bacterial communities associated with the invasive Rhodophyta Asparagopsis spp.…”