Biological manganese-dependent sulfide oxidation impacts elemental gradients in redox-stratified systems: indications from the Black Sea water column

Abstract

The reduction of manganese oxide with sulfide in aquatic redox-stratified systems was previously considered to be mainly chemical, but recent isolation of the Black Sea isolate Candidatus Sulfurimonas marisnigri strain SoZ1 suggests an important role for biological catalyzation. Here we provide evidence from laboratory experiments, field data, and modeling that the latter process has a strong impact on redox zonation in the Black Sea. High relative abundances of Sulfurimonas spp. across the redoxcline in the central western gyre of the Black Sea coincided with the high-level expression of both the sulfide:quinone oxidoreductase gene (sqr, up to 93% expressed by Sulfurimonas spp.) and other sulfur oxidation genes. The cell-specific rate of manganese-coupled sulfide oxidation by Ca. S. marisnigri SoZ1 determined experimentally was combined with the in situ abundance of Sulfurimonas spp. in a one-dimensional numerical model to calculate the vertical sulfide distribution. Abiotic sulfide oxidation was too slow to counterbalance the sulfide flux from euxinic water. We conclude that microbially catalyzed Mn-dependent sulfide oxidation influences the element cycles of Mn, S, C, and N and therefore the prevalence of other functional groups of prokaryotes (e.g., anammox bacteria) in a sulfide-free, anoxic redox zone.

Biosynthesis of H-GDGTs linked to ocean oxygen deficiency

“…One significant advantage of using lipid biomarkers for paleoenvironmental studies is their enduring preservation in the geological records. We first examined the relative abundance of H-GDGTs lipids in modern seas, alongside direct measurements of oxygen levels (40)(41)(42). The findings from the three sites in the Baltic Sea and Black Sea revealed that that H-GDGTs were much more prevalent in oxygen-deficient waters compared to oxic waters (Fig.…”

Supplementation of Polymeric Reservoirs with Redox-Responsive Metallic Nanoparticles as a New Concept for the Smart Delivery of Insulin in Diabetes

“…The ability to oxidize glucose, in fact, was used to justify the proposition for the use of manganese oxide (Mn x O y ) nanoparticles as facilitators of the starvation of cancer cells [ 56 ]. Manganese, moreover, is an element that cycles across the ecosphere in its various redox states, such as in deep-sea basins, where dissolved Mn 2+ and intermediate Mn 3+ species are transported upward by diffusion until they are oxidized into Mn 4+ and form MnO 2 , which is solid and is transported downward due to gravity, toward anaerobic depths where it then undergoes reduction by sulfides and continues cycling [ 57 ]. This omnipresence of manganese redox processes and their essentiality for life provides strong support for choosing this element for incorporation into the smart drug delivery carrier investigated here.…”

Changes in the membrane lipid composition of a Sulfurimonas species depend on the electron acceptor used for sulfur oxidation

“…The biologically catalyzed oxidation of HS - by Ca . S. marisnigri SoZ1 is faster than the abiotic oxidation of HS - with MnO 2 [ 14 ] and yields as the prominent end product, while elemental sulfur (S 0 ) accumulates in the abiotic reaction [ 13 , 15 , 16 ]. Combining the cellular abundance of Sulfurimonas spp.…”

“…in the Black Sea redoxcline with rates of MnO 2 dependent HS - oxidation by Ca . S. marisnigri SoZ1 in a reaction diffusion model yielded adequate rates to counterbalance the HS - flux, resulting in the measured HS - concentration profile, in contrast to a pure abiotic reaction [ 14 ]. Hence, this process is likely to play a prominent role in HS - oxidation at the chemocline of the Black Sea.…”

“…These studies revealed the important role of MnO 2 -dependent Sulfurimonas spp. in biogeochemical cycling in redox-stratified systems [ 14 ]. Changes in the electron acceptor are associated with differences in the electron transport chain (ETC), which is embedded in the cellular membrane.…”