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Abstract Cable bacteria are long, filamentous, multicellular bacteria that grow in marine sediments and couple sulfide oxidation to oxygen reduction over centimetre‐scale distances via long‐distance electron transport. Cable bacteria can strongly modify biogeochemical cycling and may affect microbial community networks. Here we examine interspecific interactions with marine cable bacteria (Ca. Electrothrix) by monitoring the succession of 16S rRNA amplicons (DNA and RNA) and cell abundance across depth and time, contrasting sediments with and without cable bacteria growth. In the oxic zone, cable bacteria activity was positively associated with abundant predatory bacteria (Bdellovibrionota, Myxococcota, Bradymonadales), indicating putative predation on cathodic cells. At suboxic depths, cable bacteria activity was positively associated with sulfate‐reducing and magnetotactic bacteria, consistent with cable bacteria functioning as ecosystem engineers that modify their local biogeochemical environment, benefitting certain microbes. Cable bacteria activity was negatively associated with chemoautotrophic sulfur‐oxidizing Gammaproteobacteria (Thiogranum,Sedimenticola) at oxic depths, suggesting competition, and positively correlated with these taxa at suboxic depths, suggesting syntrophy and/or facilitation. These observations are consistent with chemoautotrophic sulfur oxidizers benefitting from an oxidizing potential imparted by cable bacteria at suboxic depths, possibly by using cable bacteria as acceptors for electrons or electron equivalents, but by an as yet enigmatic mechanism.
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Microdiversity and temporal dynamics of marine bacterial dimethylsulfoniopropionate genes
Summary Dimethylsulfoniopropionate (DMSP) is an abundant organic sulfur metabolite produced by many phytoplankton species and degraded by bacteria via two distinct pathways with climate‐relevant implications. We assessed the diversity and abundance of bacteria possessing these pathways in the context of phytoplankton community composition over a 3‐week time period spanning September–October, 2014 in Monterey Bay, CA. ThedmdAgene from the DMSP demethylation pathway dominated the DMSP gene pool and was harboured mostly by members of the alphaproteobacterial SAR11 clade and secondarily by the Roseobacter group, particularly during the second half of the study. Novel members of the DMSP‐degrading community emerged fromdmdAsequences recovered from metagenome assemblies and single‐cell sequencing, including largely uncharacterized gammaproteobacteria and alphaproteobacteria taxa. In the DMSP cleavage pathway, the SAR11 genedddKwas the most abundant early in the study, but was supplanted bydddPover time. SAR11 members, especially those harbouring genes for both DMSP degradation pathways, had a strong positive relationship with the abundance of dinoflagellates, and DMSP‐degrading gammaproteobacteria co‐occurred with haptophytes. Thisin situstudy of the drivers of DMSP fate in a coastal ecosystem demonstrates for the first time correlations between specific groups of bacterial DMSP degraders and phytoplankton taxa.
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- Award ID(s):
- 1656311
- PAR ID:
- 10461595
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Environmental Microbiology
- Volume:
- 21
- Issue:
- 5
- ISSN:
- 1462-2912
- Format(s):
- Medium: X Size: p. 1687-1701
- Size(s):
- p. 1687-1701
- Sponsoring Org:
- National Science Foundation
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