Study Identifies How Coral Bacteria Export Carbon from DMSP, Completing a Key Metabolic Cycle
Researchers have shown that Endozoicomonas bacteria in coral holobionts degrade the sulfur compound DMSP and export the resulting acetate, making it available to other coral symbionts. The study used gas chromatography, stable isotope labeling, and transcriptomics to trace carbon flow from DMSP through bacterial metabolism to acetate excretion. The findings fill a gap in understanding coral symbiont nutrient sharing, while also revealing that elevated temperatures reduce this bacterial activity.
A new preprint study on bioRxiv investigates how Endozoicomonas ruthgatesiae, a dominant bacterium in coral holobionts, processes dimethylsulfoniopropionate (DMSP) and exports acetate as a byproduct. Using gas chromatography-mass spectrometry, the researchers confirmed a significant increase in acetate excretion when the bacterium was exposed to DMSP, and stable isotope labeling verified that this acetate was directly derived from DMSP carbon. Transcriptomic analysis showed that DMSP exposure upregulated the dddD gene and caused a broad metabolic shift, including downregulation of the TCA cycle and the Pta-AckA pathway, with carbon flux redirected toward the glyoxylate shunt. This metabolic reconfiguration suggests the bacterium prioritizes DMSP catabolism over biomass production, resulting in acetate being released into the holobiont environment where other symbionts and potentially the coral host can access it. A notable finding is that elevated water temperatures diminish the bacterium's DMSP cleavage activity, raising questions about how coral metabolic networks may be disrupted under climate-driven ocean warming.
What's missing
The study is a preprint and has not yet undergone peer review. Key open questions include whether the exported acetate is demonstrably taken up by the coral host or other specific symbionts in vivo, what temperature thresholds are sufficient to meaningfully impair DMSP cleavage activity under realistic reef conditions, and whether findings from the single model strain (8E) generalize to other Endozoicomonas strains or coral species. The study does not address the ecological consequences of reduced DMSP cycling under bleaching-level thermal stress.
What different sources said
- bioRxivCenter
The missing part of the DMSP cycle in coral holobionts: Endozoicomonas exports acetate derived from DMSP degradation
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.