Discovery of Afifi, the shallowest and southernmost brine pool reported in the Red Sea

Abstract

The previously uncharted Afifi brine pool was discovered in the eastern shelf of the southern Red Sea. It is the shallowest brine basin yet reported in the Red Sea (depth range: 353.0 to 400.5 m). It presents a highly saline (228 g/L), thalassohaline, cold (23.3 °C), anoxic brine, inhabited by the bacterial classes KB1, Bacteroidia and Clostridia and the archaeal classes Methanobacteria and Deep Sea Euryarcheota Group. Functional assignments deduced from the taxonomy indicate methanogenesis and sulfur respiration to be important metabolic processes in this environment. The Afifi brine was remarkably enriched in dissolved inorganic carbon due to microbial respiration and in dissolved nitrogen, derived from anammox processes and denitrification, according to high δ 15 N values (+6.88‰, AIR). The Afifi brine show a linear increase in δ 18 O and δD relative to seawater that differs from the others Red Sea brine pools, indicating a non-hydrothermal origin, compatible with enrichment in evaporitic environments. Afifi brine was probably formed by venting of fossil connate waters from the evaporitic sediments beneath the seafloor, with a possible contribution from the dehydration of gypsum to anhydrite. Such origin is unique among the known Red Sea brine pools.Submarine brine pools are bodies of water with elevated salinity that form lake-like structures on the seafloor.

Patterns and Drivers of Extracellular Enzyme Activity in New Zealand Glacier-Fed Streams

“…While we acknowledge that fresh sediment is ideal for EEA analyses, freezing is an acceptable preservation method when logistically necessary (Hewins et al, 2016). Lastly, approximately 2.5-3 g of wet sediment for bacterial abundance (BA) was collected in a cryovial and fixed in 1.8 ml filter-sterilized paraformaldehyde/glutaraldehyde solution (1% w/v paraformaldehyde, 0.05% w/w glutaraldehyde; Duarte et al, 2020), flash-frozen in the field, and stored at −80 • C until analysis.…”

Fine-scale metabolic discontinuity in a stratified prokaryote microbiome of a Red Sea deep halocline

“…Filtered and unfiltered results were not significantly different indicating that >95% of all C and N was in dissolved phase. In parallel, triplicate seawater and brine samples of 1.62 ml per each depth were fixed with 180 μl of paraformaldehyde and glutaraldehyde fixing solution for a total volume of 1.8 ml per sample, and stored in liquid nitrogen for enumeration of microbial cells using flow cytometry, as in Duarte et al [ 26 ]. The gating strategy is shown in Supplementary Fig.…”

“…The quantification of nitrogen cycle-related functional genes, archaeal and bacterial ammonia monooxygenase subunit A ( amoA ) and hzo was carried out following the methods described by Duarte et al [ 26 ] and elsewhere [ 63 , 64 ]. Briefly, the fragments of interest were amplified from total genomic DNA isolated from environmental samples by PCR and cloned into into pCR™2.1-TOPO® vectors.…”

Novel Enzymes From the Red Sea Brine Pools: Current State and Potential

“…Thus, enhancing enzyme stability can markedly lower industry expenses (Jin et al, 2019). For some reaction conditions, enzymes can be sufficiently stabilized by surface modifications, e.g., PEGylation or immobilization (Dumorne et al, 2017;Ellis, 2019). However, ideally, industry would need enzymes that can naturally and reproducibly withstand a combination of several extreme conditions (pH, temperature, salinity, organic solvents, and/or aerification) (Sarmiento et al, 2015;Dumorne et al, 2017;Kara and Liese, 2019).…”

“…For some reaction conditions, enzymes can be sufficiently stabilized by surface modifications, e.g., PEGylation or immobilization (Dumorne et al, 2017;Ellis, 2019). However, ideally, industry would need enzymes that can naturally and reproducibly withstand a combination of several extreme conditions (pH, temperature, salinity, organic solvents, and/or aerification) (Sarmiento et al, 2015;Dumorne et al, 2017;Kara and Liese, 2019). Naturally, halotolerant enzymes are of particular interest for biotech applications because high salt concentrations correspond to low water activity and hence to increased tolerance to organic solvents.…”