DPANN symbiont of Haloferax volcanii accelerates xylan degradation by the non-host haloarchaeon Halorhabdus sp.
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Elsevier
Abstract
This study examines a natural consortium of halophilic archaea, comprising xylan-degrading Halorhabdus sp. SVX81, consortium cohabitant Haloferax volcanii SVX82 (formerly H. lucentense SVX82), and its DPANN ectosymbiont Ca. Nanohalococcus occultus SVXNc. Transcriptomics and targeted metabolomics demonstrated that the tripartite consortium outperformed individual and the Halorhabdus sp. SVX81 with H. volcanii SVX82 bipartite cultures in xylan degradation, exhibiting a division of labor: the DPANN symbiont processed glycolysis products, while other members performed xylan depolymerization and biosynthesis of essential compounds. Electron microscopy and cryo-electron tomography revealed the formation of heterocellular biofilms interlinked by DPANN cells. The findings demonstrated that DPANN symbionts can interact directly with other members of microbial communities, which are not their primary hosts, influencing their gene expression. However, DPANN proliferation requires their primary host presence. The study highlights the collective contribution of consortium members to xylan degradation and their potential for biotechnological applications in the management of hypersaline environments.
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SUPPLEMENTARY MATERIAL : DOCUMENT S1. Figures S1–S3 and Table S2. TABLE S1. Reads per Kilo base per Million mapped reads (RPKM) values of expression of functional genes of Haloferax volcanii SVX82 in four different archaeal consortia. (I) Axenic monoculture on xylose; (II) In a consortium with Ca. N. occultus SVXNc on xylose; (III) With Halorhabdus sp. SVX81 on xylan; and (IV) In a tripartite culture on xylan. TABLE S3. Haloferax volcanii genes expressed in the axenic culture, whose transcripts were not detected in the tripartite culture with Halorhabdus sp. and Ca. Nanohalococcus occultus SVXNc on xylan. TABLE S4. Gene co-regulation in Haloferax volcanii SVX82 (Hfx) and Halorhabdus sp. SVX81 (Hrh) under effect of Ca. Nanohalococcus occultus SVXNc. TABLE S5. Highly expressed and differentially expressed genes of Ca. Nanohalococcus occultus SVXNc_ in the tripartite culture on xylan compared to the bipartite culture with Haloferax volcanii SVX82 on xylose. TABLE S6. Co-regulation and counter-regulation of genes in Haloferax volcanii SVX82 affected by the presence of the DPANN symbiotic archaeon Ca. Nanohalococcus occultus SVXNc, compared to gene expression in the axenic culture of H. volcanii SVX82 on xylose and in the tripartite consortium on xylan with Halorhabdus sp. SVX81, respectively.
Keywords
DPANN symbiont, Haloferax volcanii, Xylan degradation, Halorhabdus sp., Archaeal consortium, Heterocellular biofilms, Metabolism, Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, and Nanohaloarchaeota (DPANN)
Sustainable Development Goals
SDG-15: Life on land
Citation
Reva, O.N., La Cono, V., Marturano, L. et al. 2025, 'DPANN symbiont of Haloferax volcanii accelerates xylan degradation by the non-host haloarchaeon Halorhabdus sp.', iScience, vol. 28, no. 2, art. 111749, doi : 10.1016/j.isci.2025.111749.