Harnessing the potential of the microbial sulfur cycle for environmental biotechnology.

The sulfur cycle is a complex biogeochemical cycle characterized by the high variability in the oxidation states of sulfur. While sulfur is essential for life processes, certain sulfur compounds, such as hydrogen sulfide, are toxic to all life forms. Micro-organisms facilitate the sulfur cycle, playing a prominent role even in extreme environments, such as soda lakes, acid mine drainage sites, hot springs, and other harsh habitats.

Draft genome sequence of strain B181, isolated from a fecal sample.

A mesophilic methanogen, B181 (DSM 11975) was previously isolated from a human fecal sample, grown on carbon dioxide and hydrogen, and subsequently sequenced. The reconstructed 1.9-Mb genome sequence of B181 contributes to our understanding of hydrogenotrophic, CO-reducing methanogenesis in the human gut.

Process conditions affect microbial diversity and activity in a haloalkaline biodesulfurization system.

Biodesulfurization (BD) systems that treat sour gas employ mixtures of haloalkaliphilic sulfur-oxidizing bacteria to convert sulfide to elemental sulfur. In the past years, these systems have seen major technical innovations that have led to changes in microbial community composition. Different studies have identified and discussed the microbial communities in both traditional and improved systems.

Draft genome sequence of strain Sph5, isolated from tap water filtration membrane.

Sphingomonadaceae are common membrane colonizers and biofilm formers. As part of our studies on long-term genetic changes in drinking water biofilm species, we report the draft genome sequence of strain Sph5, isolated from a tap water filtration membrane. The isolate was determined as through whole genome sequencing and assembly.

interactions between , and under hydrogenotrophic conditions.

Methanogens, reductive acetogens and sulfate-reducing bacteria play an important role in disposing of hydrogen in gut ecosystems. However, how they interact with each other remains largely unknown. This study cocultured (reductive acetogen), (sulfate reducer) and (methanogen).

Functional Insights of Salinity Stress-Related Pathways in Metagenome-Resolved Genomes.

Recently, methanogenic archaea belonging to the genus were reported to have a fundamental role in maintaining stable ecosystem functioning in anaerobic bioreactors under different configurations/conditions. In this study, we reconstructed three metagenome-assembled genomes (MAGs) from granular sludge collected from saline upflow anaerobic sludge blanket (UASB) reactors, where was previously implicated with the formation of compact and stable granules under elevated salinity levels (up to 20 g/L Na). Genome annotation and pathway analysis of the MAGs revealed a genetic repertoire supporting their growth under high salinity.

Comparative analysis of microbial communities from different full-scale haloalkaline biodesulfurization systems.

In biodesulfurization (BD) at haloalkaline and dO-limited conditions, sulfide-oxidizing bacteria (SOB) effectively convert sulfide into elemental sulfur that can be used in agriculture as a fertilizer and fungicide. Here we show which bacteria are present in this biotechnological process. 16S rRNA gene amplicon sequencing of biomass from ten reactors sampled in 2018 indicated the presence of 444 bacterial Amplicon Sequence Variants (ASVs).

Use of synthetic communities to study microbial ecology of the gut.

The application of synthetic microbial communities is an excellent approach to model the ecological interactions between microbes in the human gastrointestinal tract. Although DNA-based studies have provided a wealth of information, they do not consider the ecological properties of the human gut microbiota. Ecological interactions between gut microbes of interest can be studied by applying synthetic communities.

Proteomic Analysis of a Syntrophic Coculture of MPOB and PCA.

We established a syntrophic coculture of MPOB (SF) and PCA (GS) growing on propionate and Fe(III). Neither of the bacteria was capable of growth on propionate and Fe(III) in pure culture. Propionate degradation by SF provides acetate, hydrogen, and/or formate that can be used as electron donors by GS with Fe(III) citrate as electron acceptor.

How microbial glycosyl hydrolase activity in the gut mucosa initiates microbial cross-feeding.

The intestinal epithelium is protected from direct contact with gut microbes by a mucus layer. This mucus layer consists of secreted mucin glycoproteins. The outer mucus layer in the large intestine forms a niche that attracts specific gut microbiota members of which several gut commensals can degrade mucin.

Pelorhabdus rhamnosifermentans gen. nov., sp. nov., a strictly anaerobic rhamnose degrader from freshwater lake sediment.

A rhamnose-degrading bacterium, strain BoRhaA, was isolated from profundal sediment of Lake Constance in agar dilution series with l-rhamnose as substrate and with a background lawn of Methanospirillum hungatei. The isolated strain was a motile rod that stained Gram positive. Growth was observed within a pH range of 4.

Biofouling control: the impact of biofilm dispersal and membrane flushing.

Pure culture studies have shown that biofilm dispersal can be triggered if the nutrient supply is discontinued by stopping the flow. Stimulating biofilm dispersal in this manner would provide a sustainable manner to control unwanted biofilm growth in industrial settings, for instance on synthetic membranes used to purify water. The response of multispecies biofilms to nutrient limitation has not been thoroughly studied.

Special Issue "Anaerobes in Biogeochemical Cycles".

Anaerobic microorganisms, Bacteria and Archaea, have an essential role in global biogeochemical cycles [...

Effect of Sulfate on Carbon Monoxide Conversion by a Thermophilic Syngas-Fermenting Culture Dominated by a Species.

A syngas-degrading enrichment culture, culture T-Syn, was dominated by a bacterium closely related to strain AB33 (98% 16S rRNA gene sequence identity). Culture T-Syn could convert high CO concentrations (from pCO ≈ 34 kPa to pCO ≈ 170 kPa), both in the absence and in the presence of sulfate as external electron acceptor. The products formed from CO conversion were H and acetate.

Comparative proteomics of Geobacter sulfurreducens PCA in response to acetate, formate and/or hydrogen as electron donor.

Geobacter sulfurreducens is a model bacterium to study the degradation of organic compounds coupled to the reduction of Fe(III). The response of G. sulfurreducens to the electron donors acetate, formate, hydrogen and a mixture of all three with Fe(III) citrate as electron acceptor was studied using comparative physiological and proteomic approaches.

Syngas as Electron Donor for Sulfate and Thiosulfate Reducing Haloalkaliphilic Microorganisms in a Gas-Lift Bioreactor.

Biodesulfurization processes remove toxic and corrosive hydrogen sulfide from gas streams (e.g., natural gas, biogas, or syngas).

Butyrate Conversion by Sulfate-Reducing and Methanogenic Communities from Anoxic Sediments of Aarhus Bay, Denmark.

The conventional perception that the zone of sulfate reduction and methanogenesis are separated in high- and low-sulfate-containing marine sediments has recently been changed by studies demonstrating their co-occurrence in sediments. The presence of methanogens was linked to the presence of substrates that are not used by sulfate reducers. In the current study, we hypothesized that both groups can co-exist, consuming common substrates (H and/or acetate) in sediments.

Microbial Community Drivers in Anaerobic Granulation at High Salinity.

In the recent years anaerobic sludge granulation at elevated salinities in upflow anaerobic sludge blanket (UASB) reactors has been investigated in few engineering based studies, never addressing the microbial community structural role in driving aggregation and keeping granules stability. In this study, the combination of different techniques was applied in order to follow the microbial community members and their structural dynamics in granules formed at low (5 g/L Na) and high (20 g/L Na) salinity conditions. Experiments were carried out in four UASB reactors fed with synthetic wastewater, using two experimental set-ups.

Propionate Converting Anaerobic Microbial Communities Enriched from Distinct Biogeochemical Zones of Aarhus Bay, Denmark under Sulfidogenic and Methanogenic Conditions.

The relationship between predominant physiological types of prokaryotes in marine sediments and propionate degradation through sulfate reduction, fermentation, and methanogenesis was studied in marine sediments. Propionate conversion was assessed in slurries containing sediment from three different biogeochemical zones of Aarhus Bay, Denmark. Sediment slurries were amended with 0, 3, or 20 mM sulfate and incubated at 25 °C and 10 °C for 514-571 days.

Characterization of dairy cow rumen bacterial and archaeal communities associated with grass silage and maize silage based diets.

The objective of the present study was to characterize the rumen bacterial and archaeal communities in dairy cows fed different ratios of maize silage (MS) and grass silage (GS), and place the findings in the context of ruminal fermentation as well as previously reported methane (CH4) emissions. Rumen fluid from 12 rumen cannulated dairy cows was collected after 10 and 17 days of feeding one of four diets, all of which had the same roughage to concentrate ratio of 80:20 based on dry matter (DM). Roughage in the four diets (GS100, GS0, GS67, GS33) consisted of either 1000 g/kg DM GS (GS100), 1000 g/kg DM MS (GS0), or a mixture of both silages in different proportions [667 g/kg DM GS and 333 g/kg DM MS (GS67); 333 g/kg DM GS and 677 g/kg DM MS (GS33)].

Biodiversity and ecology of microorganisms in high pressure membrane filtration systems.

High-pressure membrane filtration (reverse osmosis and nanofiltration) is used to purify different water sources, including wastewater, surface water, groundwater and seawater. A major concern in membrane filtration is the accumulation and growth of micro-organisms and their secreted polymeric substances, leading to reduced membrane performance and membrane biofouling. The fundamental understanding of membrane biofouling is limited despite years of research, as the means of microbial interactions and response to the conditions on the membrane surface are complicated.

Concurrent use of methanol and ethanol for chain-elongating short chain fatty acids into caproate and isobutyrate.

Microbial chain elongation (MCE) is a bioprocess that could utilise a mixed-culture fermentation to valorise organic waste. MCE converting ethanol and short chain fatty acids (SCFA; derived from organic waste) to caproate has been studied extensively and implemented. Recent studies demonstrated the conversion of SCFAs and methanol or ethanol into isomerised fatty acids as novel products, which may expand the MCE application and market.

Calcium effect on microbial activity and biomass aggregation during anaerobic digestion at high salinity.

The potential effect of different Ca additions (150, 300, 450, 600 and 1000 mg/L) on microbial activity and aggregation, during anaerobic digestion at moderate (8 g/L Na) and high salinity (20 g/L Na) has been investigated. Batch tests were carried out in duplicate serum bottles and operated for 30 days at 37 °C. At 8 g/L Na, methanogenic activity and protein degradation were comparable from 150 to 450 mg/L Ca, and a significant inhibition was only observed at a Caconcentration of 1000 mg/L.