Giant sulfur bacteria (Beggiatoaceae) from sediments underlying the Benguela upwelling system host diverse microbiomes

Abstract

Due to their lithotrophic metabolisms, morphological complexity and conspicuous appearance, members of the Beggiatoaceae have been extensively studied for more than 100 years. These bacteria are known to be primarily sulfur-oxidizing autotrophs that commonly occur in dense mats at redox interfaces. Their large size and the presence of a mucous sheath allows these cells to serve as sites of attachment for communities of other microorganisms. But little is known about their individual niche preferences and attached microbiomes, particularly in marine environments, due to a paucity of cultivars and their prevalence in habitats that are difficult to access and study. Therefore, in this study, we compare Beggiatoaceae strain composition, community composition, and geochemical profiles collected from sulfidic sediments at four marine stations off the coast of Namibia. To elucidate community members that were directly attached and enriched in both filamentous Beggiatoaceae, namely Ca. Marithioploca spp. and Ca. Maribeggiatoa spp., as well as non-filamentous Beggiatoaceae, Ca. Thiomargarita spp., the Beggiatoaceae were pooled by morphotype for community analysis. The Beggiatoaceae samples collected from a highly sulfidic site were enriched in strains of sulfur-oxidizing Campylobacterota, that may promote a more hospitable setting for the Beggiatoaceae, which are known to have a lower tolerance for high sulfide to oxygen ratios. We found just a few host-specific associations with the motile filamentous morphotypes. Conversely, we detected 123 host specific enrichments with non-motile chain forming Beggiatoaceae. Potential metabolisms of the enriched strains include fermentation of host sheath material, syntrophic exchange of H2 and acetate, inorganic sulfur metabolism, and nitrite oxidation. Surprisingly, we did not detect any enrichments of anaerobic ammonium oxidizing bacteria as previously suggested and postulate that less well-studied anaerobic ammonium oxidation pathways may be occurring instead.

Nutrient turnover by large sulfur bacteria on the Namibian mud belt during the low productivity season

“…Marithioploca spp. have also been reported (Gallardo et al, 1998;Flood et al, 2021), but are probably not widely distributed, and no specimens were observed at the sites studied here or detected based on 16S-RNA (data not shown). During the fieldwork, the water mass on the inner shelf was dominated by ESACW that prevented anoxic conditions in the bottom waters (Zabel et al, 2019).…”

Polyhydroxybutyrate-producing cyanobacteria from lampenflora: The case study of the “Stiffe” caves in Italy

“…The SAR324 clade was described for the first time in the Sargasso Sea ( Wright et al, 1997 ). The distribution of this taxon is relevant in deep waters and oceans ( DeLong et al, 2006 ; Brown and Donachie, 2007 ; Ghiglione et al, 2012 ; Dick et al, 2013 ; Boeuf et al, 2021 ; Flood et al, 2021 ) and is a major component of low-oxygen environments, under dysoxic and suboxic conditions ( Boeuf et al, 2021 ). The SAR324 reports underline a high flexible metabolism and a chemoautotrophic regime ( Boeuf et al, 2021 ).…”

Outside-in: intracellular vesicles in giant sulfur bacteria contain peptidoglycan

“…We also recently discovered that Ca . Thiomargarita hosts a large number of host-specific epibionts [28]. Consideration of these microorganisms, in addition to Ca .…”

“…We also recently discovered that Ca. Thiomargarita hosts a large number of host-specific epibionts [28].…”