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Fertile chicken eggs were used as an alternative model for large animals to evaluate suspect toxic dietary ingredients for fetal loss disorders associated with mare reproductive loss syndrome (MRLS) and fetal losses in other livestock. Nitrate, ammonia, and sulfate may react with proteinaceous compounds to enable the formation of abiotic pathogenic nanoparticles which were constant findings in pathognomonic placental lesions associated with non-infectious fetal losses of previously unknown etiology in mares, chickens and other livestock. The pathogenic nanoparticles may be produced naturally by toxic elements associated with air pollution that affect pasture forages or crops, unintentionally by reactions of these elements in protein-mineral mixes in dietary rations, or endogenously within tissues of fetuses and adult animals. The nanoparticles may form niduses in small vessels and predispose animals to a host of secondary opportunistic diseases affecting the reproductive, respiratory and gastrointestinal tracts of animals. The newly recognized abiotic pathogenic micro and nanoparticles are associated with MRLS. The discovery of the pathogenic nanoparticles led to the identification of nitrate, ammonium, and sulfur, in the form of sulfate, that seemingly enable the formation of the pathogenic nanoparticles in embryonic and fetal tissues.

Biological desulfurization offers several remarkably environmental advantages of operation at ambient temperature and atmospheric pressure, no demand of toxic chemicals as well as the formation of biologically re‐usable sulfur (S0), which has attracted increasing attention compared to conventionally physicochemical approaches in removing hydrogen sulfide from sour gas. However, the low biomass of SOB, the acidification of process solution, the recovery of SOB, and the selectivity of bio‐S0 limit its industrial application. Therefore, more efforts should be made in the improvement of the BDS process for its industrial application via different research perspectives. This review summarized the recent research advances in the microbial capture of hydrogen sulfide from sour gas based on strain modification, absorption enhancement, and bioreactor modification. Several efficient solutions to limitations for the BDS process were proposed, which paved the way for the future development of BDS industrialization. [ABSTRACT FROM AUTHOR]

Thioalkalivibrio paradoxus strain ARh 1(T) is a chemolithoautotrophic, non-motile, Gram-negative bacterium belonging to the Gammaproteobacteria that was isolated from samples of haloalkaline soda lakes. It derives energy from the oxidation of reduced sulfur compounds and is notable for its ability to grow on thiocyanate as its sole source of electrons, sulfur and nitrogen. The full genome consists of 3,756,729 bp and comprises 3,500 protein-coding and 57 RNA-coding genes. This organism was sequenced as part of the community science program at the DOE Joint Genome Institute.

Thioalkalivibrio thiocyanoxidans strain ARh 2(T) is a sulfur-oxidizing bacterium isolated from haloalkaline soda lakes. It is a motile, Gram-negative member of the Gammaproteobacteria. Remarkable properties include the ability to grow on thiocyanate as the sole energy, sulfur and nitrogen source, and the capability of growth at salinities of up to 4.3 M total Na(+). This draft genome sequence consists of 61 scaffolds comprising 2,765,337 bp, and contains 2616 protein-coding and 61 RNA-coding genes. This organism was sequenced as part of the Community Science Program of the DOE Joint Genome Institute.

Sulfur-based denitrification may be a key biogeochemical nitrate (NO3−) removal process in sulfide-rich regions, but it is still poorly understood in natural terrestrial ecosystems. We examined sulfur-driven NO3− reduction using streambank soils in a headwater catchment underlain by marine sedimentary rock in Akita, Japan. In a catchment exhibiting higher sulfide content in streambed sediment, we sampled two adjacent streambank soils of streambank I (two layers) and of streambank II (eight layers). Anaerobic long-term incubation experiments (40 days, using soils of streambank I) and short-term incubation experiments (5 days, using soils of streambank II) were conducted to evaluate variations of N solutes (NO3−, NO2−, and NH4+), N gases (NO, N2O), and the bacterial flora. In both experiments, two treatment solutions containing NO3− (N treatment), and NO3− and S2O32− (N + S treatment) were prepared. In the N + S treatment of the long-term experiment, NO3− concentrations gradually decreased by 98%, with increases in the SO42−, NO2−, NO, and N2O concentrations and with not increase in the NH4+, indicating denitrification had occurred with a high probability. Temporal accumulation of NO2− was observed in the N + S treatment. The stoichiometric ratio of SO42− production and NO3− depletion rates indicated that denitrification using reduced sulfur occurred even without additional S, indicating inherent S also served as an electron donor for denitrification. In the short-term incubation experiment, S addition was significantly decreased NO3− concentrations and increased NO2−, NO, and N2O concentrations, especially in some subsoils with higher sulfide contents. Many denitrifying sulfur-oxidizing bacteria (Thiobacillus denitrificans and Sulfuricella denitrificans) were detected in both streambank I and II, which dominated up to 5% of the entire microbial population, suggesting that these bacteria are widespread in sulfide-rich soil layers in the catchment. We concluded that the catchment with abundant sulfides in the subsoil possessed the potential for sulfur-driven NO3− reduction, which could widely influence N cycling in and NO3− export from the headwater catchment.

The biogas produced in a centralized digestion plant treating high-solid sewage sludge under thermophilic conditions was biologically desulfurized via in-situ headspace micro-oxygenation. The removal of hydrogen sulfide (H 2 S) from the produced biogas was evaluated for 84 days under decreasing injection flows of oxygen (O 2), resulting in O 2 doses from 0.96(±0.03) to 0.19(±0.01) NL/Nm3 biogas. A stable H 2 S removal efficiency of 98.2(±1.3)% was obtained with an O 2 dose of 0.96(±0.03) NL/Nm3 biogas, whereas removal efficiencies of 67.4(±0.7)% were observed at the lowest O 2 dose tested. The response time of the biological desulfurization system to transient oxygen conditions was evaluated through intermittent O 2 injection. Headspace micro-oxygenation did not negatively impact the digestion performance, and the optimization of O 2 dose allowed to reach a biogas quality complying with the specification for biomethane in terms of both O 2 and H 2 S contents. Lentimicrobiaceae, Caldicoprobacteraceae, DTU014, Syntrophomonadaceae, and Rhodobacteraceae were the main microbial families responsible for biological H 2 S oxidation in digester headspace. [Display omitted] • Stable H 2 S removal of 98% was obtained with an O 2 dose of 0.96(±0.03) NL/Nm3 biogas. • Biological desulfurization response time to transient O 2 flows occurred in 10 h. • Oxygen is recommended instead of air if biogas upgrading to biomethane is targeted. • Micro-oxygenation did not disrupt the anaerobic digestion of sewage sludge. • Sulfide-oxidizing bacteria were identified on digestate surface and internal walls. [ABSTRACT FROM AUTHOR]

• The use of biofertilizer containing Thiobacillus increased the growth and chl content in radish plants. • The application of biofertilizer increased the absorption of nutrients and the content of carbohydrates. • Sulfur biofertilizer improved the photochemical efficiency of PSII. • Improved yield of plant in response to biofertilizer can be considered in reducing the consumption of chemical fertilizers. Biofertilizers containing sulfur-oxidizing bacteria increase the accessibility of roots to nutrients by reducing soil pH. These biofertilizers can significantly contribute to soil fertility and increase plant growth. The present study was conducted to investigate the effect of a mixture of sulfur biofertilizer (SB) and granular sulfur fertilizer (GSF) on the growth, absorption of some elements, and photochemical efficiency of PSII in small Raphanus sativus grown in greenhouse conditions. GSF, including 0, 200, 400, and 600 kg ha−1 was added to the soil of the pots without or with biofertilizer containing Thiobacillus bacteria. The results showed that applying biofertilizer along with different levels of GSF increased the fresh weight and contents of anthocyanins, soluble sugars, starch, and some nutrients in leaves and swollen red roots. In addition, these treatments led to an increase in shoot length and photosynthetic pigments. In plants treated with a mixture of biofertilizer and chemical fertilizer, the photochemical efficiency of photosynthesis improved. The results of this study suggest the use of SB along with GSF (even at low and medium levels) can improve the growth and photosynthetic performance of radish plants in most of the measured indicators, at least in current experimental conditions. The results of this study can be significant for less use of chemical fertilizers and the production of agricultural products with higher food security, especially in developing countries. [Display omitted] [ABSTRACT FROM AUTHOR]

• Our model predicted pH, alkalinity and LSI in coupled MBfRs producing S0. • CO 2 and HCl acidification strategies for pH control were compared with the model. • CO2 was a source of carbon and alkalinity, but increased the LSI. • In mine water treatment, HCl addition may be constrained by Cl− effluent standards. We developed a model to predict pH, alkalinity, and the Langelier Saturation Index (LSI) in coupled systems of hydrogen-based autotrophic sulfate reduction and aerobic oxidation of sulfide to elemental sulfur. To neutralize the biologically generated base, the model allows for the addition of CO 2 as part of the gas mixture, the independent addition of HCl or CO 2 , or a combination of the alternatives. The model was evaluated against the results from a laboratory system for the production of elemental sulfur from sulfate present in mine-tailings water, which is characterized by the presence of elevated sulfate and calcium concentrations. Model results were consistent with measurements of pH, alkalinity, and LSI. The model showed how the acid demands of the coupled reactors vary with pH, being approximately equivalent at pH over 8, when ionized sulfide predominates. Also, while the sulfidogenic reactor was well buffered due to the production of ionized sulfide, the sulfidotrophic reactor in the absence of sulfide and carbonate alkalinity was prone to pH declines. Considering that both reactors operated in the positive range of LSI, the model also indicated that addition of CO 2 should be minimized due to increase in the bicarbonate concentration and its effect on increasing the LSI. Furthermore, the model also showed that exclusive reliance on HCl for pH control can be incompatible with Cl− effluent standards, which means that a compromise must be reached between CO 2 and HCl additions. [ABSTRACT FROM AUTHOR]

Abstract Chemolithoautotrophic sulfur-oxidizing bacteria (SOB) are crucial key players in biotechnological processes to remove hydrogen sulfide from sour gas streams. Several different haloalkaliphilic SOB have been detected and isolated from lab- and full-scale facilities, which all performed differently considering end product yields (sulfur and sulfate) and conversion rates. Understanding and regulating bacterial community dynamics in biodesulfurization processes will enable optimization of the process operation. We developed quantitative PCR (qPCR) assays to quantify haloalkaliphilic sulfur-oxidizing gammaproteobacterial species Alkalilimnicola ehrlichii, Thioalkalivibrio sulfidiphilus, and Thioalkalibacter halophilus that dominate bacterial communities of biodesulfurization lab- and full-scale installations at haloalkaline conditions. The specificity and PCR efficiency of novel primer sets were evaluated using pure cultures of these target species. We further validated the qPCR assays by quantification of target organisms in five globally distributed full-scale biodesulfurization installations. The qPCR assays perform a sensitive and accurate quantification of Alkalilimnicola ehrlichii, Thioalkalivibrio sulfidiphilus and Thioalkalibacter halophilus, thus providing rapid and valuable insights into process performance and SOB growth dynamics in gas biodesulfurization systems.

The sulfur cycle participates significantly in life evolution. Some facultatively autotrophic microorganisms are able to thrive in extreme environments with limited nutrient availability where they specialize in obtaining energy by oxidation of reduced sulfur compounds. In our experiments focused on the characterization of halophilic bacteria from a former salt mine in Solivar (Presov, Slovakia), a high diversity of cultivable bacteria was observed. Based on ARDRA (Amplified Ribosomal DNA Restriction Analysis), at least six groups of strains were identified with four of them showing similarity levels of 16S rRNA gene sequences lower than 98.5% when compared against the GenBank rRNA/ITS database. Heterotrophic sulfur oxidizers represented ~34% of strains and were dominated by Halomonas and Marinobacter genera. Autotrophic sulfur oxidizers represented ~66% and were dominated by Guyparkeria and Hydrogenovibrio genera. Overall, our results indicate that the spatially isolated hypersaline deep subsurface habitat in Solivar harbors novel and diverse extremophilic sulfur-oxidizing bacteria.

Gold in nature is covered by rocks which contain sulfide minerals such as pyrite, chalcopyrite, arsenopyrite, and others sulfide minerals. Chemolithotrophic bacteria have the ability to oxidize the sulfur compounds and can be used in the process of releasing gold from carrier rocks which contain sulfide minerals. This research aimed to explore and identify the chemolithotrophic bacteria from gold mining areas as well as determine their potential for sulfur oxidation. The methods used in this study were exploring the potential of bacteria in sulfur oxidation and describing the variety of bacteria that were isolated from gold mining areas by 16s rRNA identification. The results showed that there were six isolates from isolation with Starkey solid medium, i.e. Bl-1, B1-2, B1-3, B1-4, B1-5 and B1-6 that were similar to Paenibacillus sp., Enterobacter ludwigiis train E8-13, uncultured Burkholderia sp., Uncultured bacterium clone N4.5, Bacillus subtilis strain CICC 10023, and Bacterium enrichment culture clone 02 respectively. The B1-3 isolate showed the highest increase of sulfate compound in the medium (8.04 % at 649.55 ppm). This indigenous bacteria will be able to be used to release gold from rock which contains sulfide minerals and reduce the use of hazardous chemicals commonly used in gold mining.

Aerobic, Gram-stain-negative, obligately chemolithoautotrophic thiosulfate-oxidizing bacteria, strains AkT22T and aks77T were isolated from a brackish lake in Japan. Strains AkT22T and aks77T were isolated from samples of eelgrass and sediment, respectively. Growth on sulfide, tetrathionate, elemental sulfur, and organic substrates was not observed for both strains. Growth of the strains was observed at 5 °C or higher temperature, with optimum growth at 22 °C. Strain AkT22T grew at a pH range of 5.8–8.0, with optimum growth at pH 6.7–7.8. Strain aks77T grew at a pH range of 5.8–8.5, with optimum growth at pH 7.0–7.9. Major cellular fatty acids (> 10% of total) of strain AkT22T were C16:1, C18:1, and C16:0. The sole respiratory quinone was ubiquinone-8 in both strains. The genome of strain AkT22T consisted of a circular chromosome, with size of approximately 2.6 Mbp and G + C content of 43.2%. Those values of the genome of strain aks77T were ca. 2.7 Mbp and 45.5%, respectively. Among cultured bacteria, Thiomicrorhabdus aquaedulcis HaS4T showed the highest sequence identities of the 16S rRNA gene, to strains AkT22T (94%) and aks77T (95%). On the basis of these results, Thiosulfativibrio zosterae gen. nov., sp. nov. and Thiosulfatimonas sediminis gen. nov., sp. nov. are proposed, with type strains of AkT22T (= BCRC 81184T = NBRC 114012T = DSM 109948T) and aks77T (= BCRC 81183T = NBRC 114013T), respectively. [ABSTRACT FROM AUTHOR]

Flavocytochrome c sulfide dehydrogenase (FCC) is one of the central enzymes of the respiratory chain in sulfur-oxidizing bacteria. FCC catalyzes oxidation of sulfide and polysulfide ions to elemental sulfur accompanied by electron transfer to cytochrome c. The catalytically active form of the enzyme is a non-covalently linked heterodimer composed of flavin- and heme-binding subunits. The Thioalkalivibrio paradoxus ARh1 genome contains five copies of genes encoding homologous FCCs with an amino acid sequence identity from 36 to 54%. When growing on thiocyanate or thiosulfate as the main energy source, the bacterium synthesizes products of different copies of FCC genes. In this work, we isolated and characterized FCC synthesized during the growth of Tv. paradoxus on thiocyanate. FCC was shown to oxidize exclusively sulfide but not other reduced sulfur compounds, such as thiosulfate, sulfite, tetrathionate, and sulfur, and it also does not catalyze the reverse reaction of sulfur reduction to sulfide. Kinetic parameters of the sulfide oxidation reaction are characterized. [ABSTRACT FROM AUTHOR]

Antarctic sea-ice is exposed to a wide range of environmental conditions during its annual existence; however, there is very little information describing the change in sea-ice-associated microbial communities (SIMCOs) during the changing seasons. It is well known that during the solar seasons, SIMCOs play an important role in the polar carbon-cycle, by increasing the total photosynthetic primary production of the South Ocean and participating in the remineralization of phosphates and nitrogen. What remains poorly understood is the dynamic of SIMCO populations and their ecological contribution to carbon and nutrient cycling throughout the entire annual life of Antarctic sea-ice, especially in winter. Sea ice at this time of the year is an extreme environment, characterized by complete darkness (which stops photosynthesis), extremely low temperatures in its upper horizons (down to −45 °C) and high salinity (up to 150–250 psu) in its brine inclusions, where SIMCOs thrive. Without a permanent station, wintering expeditions in Antarctica are technically difficult; therefore, in this study, the process of autumn freezing was modelled under laboratory conditions, and the resulting ‘young ice’ was further incubated in cold and darkness for one month. The ice formation experiment was primarily designed to reproduce two critical conditions: (i) total darkness, causing the photosynthesis to cease, and (ii) the presence of a large amount of algae-derived organic matter. As expected, in the absence of photosynthesis, the activity of aerobic heterotrophs quickly created micro-oxic conditions, which caused the emergence of new players, namely facultative anaerobic and anaerobic microorganisms. Following this finding, we can state that Antarctic pack-ice and its surrounding ambient (under-ice seawater and platelet ice) are likely to be very dynamic and can quickly respond to environmental changes caused by the seasonal fluctuations. Given the size of Antarctic pack-ice, even in complete darkness and cessation of photosynthesis, its ecosystem appears to remain active, continuing to participate in global carbon-and-sulfur cycling under harsh conditions.

A facultatively anaerobic sulfur-oxidizing bacterium, strain skT11T, was isolated from anoxic lake water of a stratified freshwater lake. As electron donor for chemolithoautotrophic growth, strain skT11T oxidized thiosulfate, tetrathionate, and elemental sulfur under nitrate-reducing conditions. Oxygen-dependent growth was observed under microoxic conditions, but not under fully oxygenated conditions. Growth was observed at a temperature range of 5–37 °C, with optimum growth at 28 °C. Strain skT11T grew at a pH range of 5.1–7.5, with optimum growth at pH 6.5–6.9. Heterotrophic growth was not observed. Major components in the cellular fatty acid profile were C16:1 and C16:0. The complete genome of strain skT11T consisted of a circular chromosome with a size of 3.8 Mbp and G + C content of 60.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the strain skT11T is related to sulfur-oxidizing bacteria of the genera Sulfuricella, Sulfurirhabdus, and Sulfuriferula, with sequence identities of 95.4% or lower. The analysis also indicated that these three genera should be excluded from the family Gallionellaceae, as members of another family. On the basis of its genomic and phenotypic properties, strain skT11T (= DSM 110711 T = NBRC 114323 T) is proposed as the type strain of a new species in a new genus, Sulfurimicrobium lacus gen. nov., sp. nov. In addition, emended descriptions of the families Gallionellaceae and Sulfuricellaceae are proposed to declare that Sulfuricellaceae is not a later synonym of Gallionellaceae. [ABSTRACT FROM AUTHOR]

Salinity negatively affects growth of sulfur-oxidizing bacteria (SOB) and their sulfate production ability, meanwhile decreases the available sulfate for plants in soil. The aim of this study was to isolate and characterize the bacteria of genus Halothiobacillus, as a salt-tolerant SOB, from saline and sulfidic habitats of Iran for the first time and evaluating the effect of salinity on their biomass and sulfate production during the oxidation of different sulfur sources. Isolation process and surveying the morphological, biochemical and 16S rRNA gene analysis resulted into identification of three species (eight strains) of Halothiobacillus genus including H. neapolitanus, H. hydrothermalis and H. halophilus. Salinity (0, 0.5, 1, 2 and 4 M NaCl) had a significant impact (p ≤ 0.01) on bacterial biomass and sulfate production during the oxidation of thiosulfate and elemental sulfur. Biomass and sulfate production by strains was accompanied by a decrease in residual content of thiosulfate (RCT) in medium. The amount of produced biomass and sulfate in medium supplemented by thiosulfate was much higher than elemental sulfur. The highest amount of biomass and sulfate was produced by H. neapolitanus strain I19 at 0.5 and 1 M NaCl concentration. The results of this study could be the first step to focus on the application of these bacteria to increase sulfate storage of saline soils and crop production. [ABSTRACT FROM AUTHOR]

The role of microorganisms in destructive processes occurring in concrete and reinforced concrete structures is considered. The mechanisms of microbiological effects on concrete surfaces and in the formation of microbial biofilms, are described. The main groups of corrosive microorganisms — in particular sulfur-oxidizing and sulfate-reducing microorganisms—are characterized. The principal methods for analyzing the processes of microbiological corrosion and protection of concrete from biological destruction are adduced. [ABSTRACT FROM AUTHOR]

• The clogging and dilution of biogas depend on dissolved oxygen (DO). • pH depends on Sufur oxidizing bacteria (SOB), H 2 S solubility & DO. • Near-neutral or alkaline SOB (pH 7–8) are suitable bacteria for H 2 S removal. • Shutdown the biotrickling filters increases H 2 S removal & reduces biogas clogging. • The end-products in anoxic process depends on N/S ratio. The presence of hydrogen sulfide (H 2 S) in biogas negatively affects human health and corrodes metal. Therefore, the removal of H 2 S from biogas before using is an essential requirement in many cases. Recently, biotrickling filters (BTFs) have been widely applied to the treatment of H 2 S on both laboratory and industrial scales. However, BTFs method also has some drawbacks such as low mass transfer efficiency, clogging the bed filter due to further elemental sulfur (S) excess accumulation, and biogas dilution. This paper reviews the recent development of aerobic BTF systems and solutions for those limitations during the H 2 S oxidation process in biogas. In addition, the factors affecting H 2 S removal efficiency, including sulfur-oxidizing bacteria, biofilm, packing material, pH, dissolved oxygen (DO), empty bed retention time (EBRT), ingredients of nutrients for the growth of bacteria, trickling liquid and gas velocity, are also discussed. Finally, the current strength of research in the field of H 2 S removal in biogas using BTF and its future prospects are also suggested. Some of highest elimination capacity (EC) of 78.57 g H 2 S/m3h, 144 g H 2 S/m3h, 228.6 g H 2 S/m3h were obtained from previous experiments. [ABSTRACT FROM AUTHOR]

Shallow-water hydrothermal vents are widespread, especially in the Mediterranean Sea, owing to the active volcanism of the area. Apart free microbial communities’ investigations, few biological studies have been leaded yet. Investigations of microbial communities associated with Nematoda, an ecologically important group in sediments, can help to improve our overall understanding of these ecosystems. We used a multidisciplinary-approach, based on microscopic observations (scanning electron microscopy: SEM and Fluorescence In Situ Hybridization: FISH) coupled with a molecular diversity analysis using metabarcoding, based on the 16S rRNA gene (V3-V4 region), to characterize the bacterial community of a free-living marine nematode and its environment, the shallow hydrothermal vent near Naples (Italy). Observations of living bacteria in the intestine (FISH), molecular and phylogenetic analyses showed that this species of nematode harbors its own bacterial community, distinct from the surrounding sediment and water. Metabarcoding results revealed the specific microbiomes of the sediment from three sites of this hydrothermal area to be composed mainly of sulfur oxidizing and reducing related bacteria.

The biogenic production of toxic H2S gas in sulfate-rich oil sands tailings ponds is associated with strong environmental concerns. Beside precipitation into sulfide minerals and chemical re-oxidation, microbial sulfur oxidation may catalyze sulfide re-cycling but potentially contributes to acid rock drainage (ARD) generation. To evaluate the microbial potential for sulfur oxidation, we conducted a microcosm-based pilot study with tailings of an active pond. Incubations were performed under oxic and anoxic conditions, with and without KNO3 as an electron acceptor and thiosulfate as a common substrate for microbial sulfur oxidation. The highest potentials of sulfur oxidation occurred in oxic assays (1.21 mmol L−1 day−1). Under anoxic conditions, rates were significantly lower and dominated by chemical transformation (0.09 mmol L−1 day−1; p < 0.0001). The addition of KNO3 to anoxic incubations increased microbial thiosulfate oxidation 2.5-fold (0.23 mmol L−1 day−1; p = 0.0474), with complete transformation to SO42− coupled to NO3− consumption, pointing to the activity of sulfur-oxidizing bacteria (SOB) under nitrate-reducing conditions. Importantly, in the presence of KNO3, a decrease in sedimentary sulfides was associated with an increase in S0, which indicates the potential for microbially mediated oxidation of sulfide minerals and ARD generation. Furthermore, the comparative analysis of sediments from other anthropogenic aquatic habitats demonstrated high similarities with respect to viable SOB counts and corresponding activity rates.

This study focuses on utilizing a plant-derived urease enzyme (PDUE)–urea mixture to remove heavy metals from water as constituents of nano-carbonate minerals. The bio-removal process was conducted by individually mixing PbCl2, CuCl2, and NiCl2 solutions with a PDUE–urea mixture, followed by incubation for 24 h at 23 ± 2 °C. The preliminary results revealed that the proposed method exhibited high Pb removal efficiency (˃ 99%) in a short time (8 h); meanwhile, moderate Cu and Ni removal efficiencies (67.91% and 58.49%, respectively) were obtained at the same incubation time. The concentration of heavy metals (50–200 mM) had an insignificant effect on the bio-removal rate, indicating that the PDUE–urea mixture is highly effective for the removal of heavy metals at different concentrations. The bio-removal process involved the transformation of soluble heavy metals into insoluble carbonate materials. A spherically shaped nano-cerussite (4–15 nm), a malachite hexahydrate nanosheet (thickness 8 nm), and an ultrafine micro-hellyerite (thickness 0.3 μm) were the main minerals produced by the Pb, Cu, and Ni bio-removal processes, respectively. As a beneficial application, nano-cerussite was used as an additive in an alkali-activated slag/ceramic waste-based geopolymeric coating. A preliminary study proved that increasing the nano-cerussite content enhanced the resistance of the geopolymeric coating to sulfur-oxidizing bacteria, which is detrimental to normal concrete, particularly in sewer systems. [ABSTRACT FROM AUTHOR]

Shallow-water hydrothermal vents are widespread, especially in the Mediterranean Sea, owing to the active volcanism of the area. Apart free microbial communities' investigations, few biological studies have been leaded yet. Investigations of microbial communities associated with Nematoda, an ecologically important group in sediments, can help to improve our overall understanding of these ecosystems. We used a multidisciplinary-approach, based on microscopic observations (scanning electron microscopy: SEM and Fluorescence In Situ Hybridization: FISH) coupled with a molecular diversity analysis using metabarcoding, based on the 16S rRNA gene (V3-V4 region), to characterize the bacterial community of a free-living marine nematode and its environment, the shallow hydrothermal vent near Naples (Italy). Observations of living bacteria in the intestine (FISH), molecular and phylogenetic analyses showed that this species of nematode harbors its own bacterial community, distinct from the surrounding sediment and water. Metabarcoding results revealed the specific microbiomes of the sediment from three sites of this hydrothermal area to be composed mainly of sulfur oxidizing and reducing related bacteria. [ABSTRACT FROM AUTHOR]

Biogas from distillery anaerobic digesters in the ethanol industry consist of hydrogen sulfide (H 2 S) at concentrations up to 12,000 ppm. Before being used as a feed for an electrical generator H 2 S levels need to be reduced to concentrations below 100 ppm. H 2 S removal performance depends on the activity of sulfur-oxidizing bacteria (SOB). Next Generation Sequencing (NGS) analysis of samples collected from the bioscrubber with 3 different samples including starting seed (TRE1), recirculating liquid (TRE2), bioscrubber plastic media (TRE3) were taken. Genera Fastidiosipila belonging to the phylum Firmicutes was dominant in the starting seed, while genera Pseudomonas, MWH UniP1_aquatic_group, Hydrogenophaga belonging to phyla Proteobacteria were dominant in the bioscrubber. Pseudomonas anguilliseptica (33%) and Pseudomonas alcaligenes (18%) were the major members of facultative chemoautotrophic SOB in the bioscrubber. Two species of SOB were isolated using a selective culture medium technique including Sphingobium yanoikuyae and Enhydrobacter aerosaccus. • Sulfide oxidizing bacteria (SOB) community in full scale bioscrubber treating H 2 S in distillery derived biogas was elucidated. • SOB isolated from cultural dependent technique was identified by full length 16S rRNA gene. • Next generation sequencing (NGS) of short read 16S region were employed to identifiy the SOB communities. • SOB plays a key role in a removal efficiency and stability system of hydrogen sulfide in biogas. [ABSTRACT FROM AUTHOR]

This Special Issue contains three articles and two reviews. The biological reactors used in the studies were fed with real biogas from Landfill or STPs. One research article concerns the use of a pilot scale plant with a combined process with a chemical and biological system. The other two studies concern anoxic biotrickling filters, with one study focused on the study of variable operation and its optimization through the response surface methodology, and the other focused on the selection of packing material. The reviews concern the current state of biogas desulfurization technologies, including an economic analysis, and the microbial ecology in biofiltration units. This Issue highlights some of the most relevant aspects about biogas desulfurization. [ABSTRACT FROM AUTHOR]

The potential of using iron-oxidizing and sulfur-oxidizing bioleaching process for removal of heavy metals (HMs) was investigated at initial unadjusted pH of pig manure (PM). The indigenous iron-oxidizing and sulfur-oxidizing microorganisms enriched from PM were primarily Alicyclobacillus and Acidithiobacillus thiooxidans, respectively. After 12 days of bioleaching, 95% of Cu, 96.5% of Zn, 93.6% of Mn, and 92.7% of Cd were removed from the PM in sulfur-oxidizing bioleaching process. Besides, 92.9% of Cu, 94.1% of Zn, 91.9% of Mn, and 90.5% of Cd were removed in iron-oxidizing bioleaching process. Furthermore, 18.1% of TN, 63.3% of TP, 65.4% of TK, and 45.6% of TOC were leached from the PM in the sulfur-oxidizing bioleaching process, whereas only 21.6% of TN, 32.8% of TP, 4% of TK, and 49% of TOC were solubilized in the iron-oxidizing bioleaching process. The X-ray diffraction analysis results demonstrated that there was a large amount of sulfur remained in bioleached manure from the sulfur-oxidizing process which poses a potential risk of soil re-acidification. The Standards, Measurements and Testing Program extraction protocol study on fraction of P in PM showed that the amount of bioavailable P in the sulfur-oxidizing bioleaching process was dramatically declined, whereas it was elevated by 25.9% in the iron-oxidizing bioleaching process. The results obtained in this study indicated that both the sulfur- and iron-oxidizing bioleaching process were able to efficiently remove HMs from PM at initial unadjusted pH, whereas the iron-oxidizing process was proved better method in reserving the fertilizing property and more friendly to the environment. [ABSTRACT FROM AUTHOR]

Sulfide produced from sewers is considered one of the dominant threats to public health and sewer lifespan due to its toxicity and corrosiveness. In this study, we developed an environmentally friendly strategy for gaseous sulfide control by enriching indigenous sulfur-oxidizing bacteria (SOB) from sewer sediment. Ceramics acted as bio-carriers for immobilizing SOB for practical use in a lab-scale sewer reactor. 16 S rRNA gene sequences revealed that the SOB consortium was successfully enriched, with Thiobacillus , Pseudomonas , and Alcaligenes occupying a dominant abundance of 64.7% in the microbial community. Metabolic pathway analysis in different acclimatization stages indicates that microorganisms could convert thiosulfate and sulfide into elemental sulfur after enrichment and immobilization. A continuous experiment in lab-scale sewer reactors confirmed an efficient result for sulfide removal with hydrogen sulfide reduction of 43.9% and 85.1% under high-sulfur load and low-sulfur load conditions, respectively. This study shed light on the promising application for sewer sulfide control by biological sulfur oxidation strategy. [Display omitted] • SOB were utilized for sulfide control in sewer networks. • SOB were obtained from in-situ sediment and Thiobacillus played a crucial role. • Sqr, Fcc, and Sox were the major pathways with S(0) as the terminal. • The sulfide suppression could reach above 85%. [ABSTRACT FROM AUTHOR]

Introduction: Dischargeing hazardous pollutants of oil and gas industries such as spent caustic into the soil and water is an environmental concern for which biological treatment could offer a solution. To remove high levels of sulfur compounds in spent caustic waste, isolation of chemolithoautotrophic sulfur-oxidizing bacteria from Meighan wetland was considered in this study. Materials and methods: For isolation of chemolithoautotroph haloalkaliphile sulfur-oxidizing bacteria, alkaline sulfur-respiring medium with sodium thiosulfate as the sole electron and energy source and sodium carbonate/bicarbonate as carbon source were utilized. To confirm that the purified isolates are obligated autotroph, their growth on nutrient agar medium was surveyed and selected strains were identified based on 16S rRNA sequence analysis. The growth and activity of selected strain named EMA were optimized at various pHs and salt conditions by assessment of protein content and remained thiosulfate in the culture medium. Results: Following enrichment, 10 chemolithoautotrophic, haloalkaliphilic sulfur-oxidizing strains were isolated. 16S rRNA sequence analysis, showed that the strains belonged to the genus Thioalkalivibrio. The optimal growth and thiosulfate removal of the selected strain were obtained at pH 10 and 50 g/l of salt (sodium chloride or sodium sulfate). At higher salt concentrations, thiosulfate removal was higher in the presence of sodium sulfate, rather than sodium chloride. Discussion and conclusion: high sulfur removal activity of the isolated haloalkaliphilic Thioalkalivibrio strains in extreme conditions with these bacteria could be promising for the biotreatment of spent caustic.

The genus Thioalkalivibrio includes haloalkaliphilic chemolithoautotrophic sulfur-oxidizing bacteria isolated from various soda lakes worldwide. Some of these lakes possess in addition to their extreme haloalkaline environment also other harsh conditions, to which Thioalkalivibrio needs to adapt. An example is arsenic in soda lakes in eastern California, which is found there in concentrations up to 3000 μM. Arsenic is a widespread element that can be an environmental issue, as it is highly toxic to most organisms. However, resistance mechanisms in the form of detoxification are widespread and some prokaryotes can even use arsenic as an energy source. We first screened the genomes of 76 Thioalkalivibrio strains for the presence of known arsenic oxidoreductases and found 15 putative ArxA (arsenite oxidase) and two putative ArrA (arsenate reductase). Subsequently, we studied the resistance to arsenite in detail in Thioalkalivibrio jannaschii ALM2T, and Thioalkalivibrio thiocyanoxidans ARh2T by comparative genomics and by growing them at different arsenite concentrations followed by arsenic species and transcriptomic analysis. Tv. jannaschii ALM2T, which has been isolated from Mono Lake, an arsenic-rich soda lake, could resist up to 5 mM arsenite, whereas Tv. thiocyanoxidans ARh2T, which was isolated from a Kenyan soda lake, could only grow up to 0.1 mM arsenite. Interestingly, both species oxidized arsenite to arsenate under aerobic conditions, although Tv. thiocyanoxidans ARh2T does not contain any known arsenite oxidases, and in Tv. jannaschii ALM2T, only arxB2 was clearly upregulated. However, we found the expression of a SoeABC-like gene, which we assume might have been involved in arsenite oxidation. Other arsenite stress responses for both strains were the upregulation of the vitamin B12 synthesis pathway, which can be linked to antioxidant activity, and the up- and downregulation of different DsrE/F-like genes whose roles are still unclear. Moreover, Tv. jannaschii ALM2T induced the ars gene operon and the Pst system, and Tv. thiocanoxidans ARh2T upregulated the sox and apr genes as well as different heat shock proteins. Our findings for Thioalkalivibrio confirm previously observed adaptations to arsenic, but also provide new insights into the arsenic stress response and the connection between the arsenic and the sulfur cycle.

Challenges to the reclamation of pyritic mine tailings arise from in situ acid generation that severely constrains the growth of natural revegetation. While acid mine drainage (AMD) microbial communities are well-studied under highly acidic conditions, fewer studies document the dynamics of microbial communities that generate acid from pyritic material under less acidic conditions that can allow establishment and support of plant growth. This research characterizes the taxonomic composition dynamics of microbial communities present during a 6-year compost-assisted phytostabilization field study in extremely acidic pyritic mine tailings. A complementary microcosm experiment was performed to identify successional community populations that enable the acidification process across a pH gradient. Taxonomic profiles of the microbial populations in both the field study and microcosms reveal shifts in microbial communities that play pivotal roles in facilitating acidification during the transition between moderately and highly acidic conditions. The potential co-occurrence of organoheterotrophic and lithoautotrophic energy metabolisms during acid generation suggests the importance of both groups in facilitating acidification. Taken together, this research suggests that key microbial populations associated with pH transitions could be used as bioindicators for either sustained future plant growth or for acid generation conditions that inhibit further plant growth.

Even in the current era of metagenomics, the interpretation of nucleotide sequence data is primarily dependent on knowledge obtained from a limited number of microbes isolated in pure culture. Thus, it is of fundamental importance to expand the variety of strains available in pure culture, to make reliable connections between physiological characteristics and genomic information. In this study, two sulfur oxidizers that potentially represent two novel species were isolated and characterized. They were subjected to whole-genome sequencing together with 7 neutrophilic and chemolithoautotrophic sulfur-oxidizing bacteria. The genes for sulfur oxidation in the obtained genomes were identified and compared with those of isolated sulfur oxidizers in the classes Betaproteobacteria and Gammaproteobacteria. Although the combinations of these genes in the respective genomes are diverse, typical combinations corresponding to three types of core sulfur oxidation pathways were identified. Each pathway involves one of three specific sets of proteins, SoxCD, DsrABEFHCMKJOP, and HdrCBAHypHdrCB. All three core pathways contain the SoxXYZAB proteins, and a cytoplasmic sulfite oxidase encoded by soeABC is a conserved component in the core pathways lacking SoxCD. Phylogenetically close organisms share same core sulfur oxidation pathway, but a notable exception was observed in the family ‘Sulfuricellaceae’. In this family, some strains have either core pathway involving DsrABEFHCMKJOP or HdrCBAHypHdrCB, while others have both pathways. A proteomics analysis showed that proteins constituting the core pathways were produced at high levels. While hypothesized function of HdrCBAHypHdrCB is similar to that of Dsr system, both sets of proteins were detected with high relative abundances in the proteome of a strain possessing genes for these proteins. In addition to the genes for sulfur oxidation, those for arsenic metabolism were searched for in the sequenced genomes. As a result, two strains belonging to the families Thiobacillaceae and Sterolibacteriaceae were observed to harbor genes encoding ArxAB, a type of arsenite oxidase that has been identified in a limited number of bacteria. These findings were made with the newly obtained genomes, including those from 6 genera from which no genome sequence of an isolated organism was previously available. These genomes will serve as valuable references to interpret nucleotide sequences.

Tarballs are formed from released or discharged crude oil containing sulfur compounds. A considerable amount and variety of sulfate-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) were identified in tarballs collected from the intertidal and supratidal zones of Alabama's Gulf beaches. Amplicon sequencing of the bacterial 16S rRNA gene showed that SRB were more abundantly distributed in the core than on the surface of tarballs, while no significant differences were observed in the distribution of SOB. To our best knowledge, this is the first report on the spatial distribution of diverse SRB and SOB in tarballs., (© The Author(s) 2024. Published by Oxford University Press on behalf of FEMS.)

Importance: Salt marshes are known for their significant carbon storage capacity, and sulfur cycling is closely linked with the ecosystem-scale carbon cycling in these ecosystems. Sulfate reducers are key for the decomposition of organic matter, and sulfur oxidizers remove toxic sulfide, supporting the productivity of marsh plants. To date, the complexity of coastal environments, heterogeneity of the rhizosphere, high microbial diversity, and uncultured majority hindered our understanding of the genomic diversity of sulfur-cycling microbes in salt marshes. Here, we use comparative genomics to overcome these challenges and provide an in-depth characterization of sulfur-cycling microbial diversity in salt marshes. We characterize communities across distinct sites and plant species and uncover extensive genomic diversity at the taxon level and specific genomic features present in MAGs affiliated with uncultivated sulfur-cycling lineages. Our work provides insights into the partnerships in salt marshes and a roadmap for multiscale analyses of diversity in complex biological systems., Competing Interests: The authors declare no conflict of interest.

To biologically inhibit the production of highly toxic sulfide in the aquaculture area, one bacterium, designated as Hydrogenovibrio thermophilus strain TT, was isolated from sediment in Jiaozhou Bay, China. The strain was found to be microaerobic mixtrophic, employing both carbon dioxide and organic carbons, e.g. citrate, lactate, glucose, and peptone as carbon sources. When it oxidized the sulfide and thiosulfate, oxygen was the optimal electron acceptor, followed by nitrite and nitrate, which benefited to removal of sulfide under low-oxygen mariculture environment. In addition, the strain TT exhibited remarkable tolerance of sulfide and thiosulfate in seawater, and it was able to oxidize 18.52 mmol L-1 S2- in 12 h or 45 mmol L-1 S2O32- in 24 h at initial pH 7.0–9.0, 30–40 °C. Therefore, this strain showed a quite promising application for biological remediation of sulfide-contaminated mariculture system. [ABSTRACT FROM AUTHOR]

Bacterial communities' composition, activity and robustness determines the effectiveness of biofiltration units for the desulfurization of biogas. It is therefore important to get a better understanding of the bacterial communities that coexist in biofiltration units under different operational conditions for the removal of H2S, the main reduced sulfur compound to eliminate in biogas. This review presents the main characteristics of sulfur-oxidizing chemotrophic bacteria that are the base of the biological transformation of H2S to innocuous products in biofilters. A survey of the existing biofiltration technologies in relation to H2S elimination is then presented followed by a review of the microbial ecology studies performed to date on biotrickling filter units for the treatment of H2S in biogas under aerobic and anoxic conditions. [ABSTRACT FROM AUTHOR]

Several studies undertaken on the biodeterioration of concrete sewer infrastructures have highlighted the better durability of aluminate-based materials. The bacteriostatic effect of aluminum has been suggested to explain the increase in durability of these materials. However, no clear demonstration of the negative effect of aluminum on cell growth has been yet provided in the literature. This present study has the aim to investigate the inhibitory potential of dissolved aluminum on non-sterile microbial cultures containing sulfur-oxidizing microorganisms. Both kinetic (maximum specific growth rate) and stoichiometric (oxygen consumption yield) parameters describing cells activity were accurately determined by using respirometry measurements coupled with modeled data obtained from fed batch cultures run for several days at pH below 4 and with increasing total aluminum (Altot) concentrations from 0 to 100 mM. Short term inhibition was observed for cells poorly acclimated to high salinity. However, inhibition was significantly attenuated for cells grown on mortar substrate. Moreover, after a rapid adaptation, and for Altot concentration up to 100 mM, both kinetic and stoichiometric growth parameters remained similar to those obtained in control culture conditions where no aluminum was added. This argued in favor of the impact of ionic strength change on the growth of sulfur-oxidizing microorganism rather than an inhibitory effect of dissolved aluminum. Other assumptions must hence be put forward in order to explain the better durability of cement containing aluminate-based materials in sewer networks. Among these assumptions, the influence of physical or chemical properties of the material (phase reactivity, porosity...) might be proposed. IMPORTANCE Biodeterioration of cement infrastructures represents 5 to 20% of observed deteriorations within the sewer network. Such biodeterioration events are mainly due to microbial sulfur-oxidizing activity which produces sulfuric acid able to dissolve cementitious material. Calcium aluminate cement materials are more resistant to biodeterioration compared to the commonly used Portland cement. Several theories have been suggested to describe this resistance, the bacteriostatic effect of aluminum is claimed to be the most plausible explanation. However, results reported by the several studies on this exact topic are highly controversial. This present study provides a comprehensive analysis of the influence of dissolved aluminum on growth parameters of long-term cultures of sulfur-oxidizing bacterial consortia sampled from different origins. Kinetic and stoichiometric parameters estimated by respirometry measurements and modeling showed that total dissolved aluminum concentrations up to 100 mM were not inhibitory but it would rather be a sudden increase in the ionic strength which could affect cell growth. Therefore, it appears that the bacteriostatic effect of aluminum on microbial growth cannot explain the better durability of aluminate based cementitious materials. [ABSTRACT FROM AUTHOR]

The genus Thioalkalivibrio includes haloalkaliphilic chemolithoautotrophic sulfur-oxidizing bacteria isolated from various soda lakes worldwide. Some of these lakes possess in addition to their extreme haloalkaline environment also other harsh conditions, to which Thioalkalivibrio needs to adapt. An example is arsenic in soda lakes in eastern California, which is found there in concentrations up to 3000 μM. Arsenic is a widespread element that can be an environmental issue, as it is highly toxic to most organisms. However, resistance mechanisms in the form of detoxification are widespread and some prokaryotes can even use arsenic as an energy source. We first screened the genomes of 76 Thioalkalivibrio strains for the presence of known arsenic oxidoreductases and found 15 putative ArxA (arsenite oxidase) and two putative ArrA (arsenate reductase). Subsequently, we studied the resistance to arsenite in detail in Thioalkalivibrio jannaschii ALM2T, and Thioalkalivibrio thiocyanoxidans ARh2T by comparative genomics and by growing them at different arsenite concentrations followed by arsenic species and transcriptomic analysis. Tv. jannaschii ALM2T, which has been isolated from Mono Lake, an arsenic-rich soda lake, could resist up to 5 mM arsenite, whereas Tv. thiocyanoxidans ARh2T, which was isolated from a Kenyan soda lake, could only grow up to 0.1 mM arsenite. Interestingly, both species oxidized arsenite to arsenate under aerobic conditions, although Tv. thiocyanoxidans ARh2T does not contain any known arsenite oxidases, and in Tv. jannaschii ALM2T, only arx B2 was clearly upregulated. However, we found the expression of a SoeABC-like gene, which we assume might have been involved in arsenite oxidation. Other arsenite stress responses for both strains were the upregulation of the vitamin B12 synthesis pathway, which can be linked to antioxidant activity, and the up- and downregulation of different DsrE/F-like genes whose roles are still unclear. Moreover, Tv. jannaschii ALM2T induced the ars gene operon and the Pst system, and Tv. thiocanoxidans ARh2T upregulated the sox and apr genes as well as different heat shock proteins. Our findings for Thioalkalivibrio confirm previously observed adaptations to arsenic, but also provide new insights into the arsenic stress response and the connection between the arsenic and the sulfur cycle. [ABSTRACT FROM AUTHOR]

Challenges to the reclamation of pyritic mine tailings arise from in situ acid generation that severely constrains the growth of natural revegetation. While acid mine drainage (AMD) microbial communities are well-studied under highly acidic conditions, fewer studies document the dynamics of microbial communities that generate acid from pyritic material under less acidic conditions that can allow establishment and support of plant growth. This research characterizes the taxonomic composition dynamics of microbial communities present during a 6-year compost-assisted phytostabilization field study in extremely acidic pyritic mine tailings. A complementary microcosm experiment was performed to identify successional community populations that enable the acidification process across a pH gradient. Taxonomic profiles of the microbial populations in both the field study and microcosms reveal shifts in microbial communities that play pivotal roles in facilitating acidification during the transition between moderately and highly acidic conditions. The potential co-occurrence of organoheterotrophic and lithoautotrophic energy metabolisms during acid generation suggests the importance of both groups in facilitating acidification. Taken together, this research suggests that key microbial populations associated with pH transitions could be used as bioindicators for either sustained future plant growth or for acid generation conditions that inhibit further plant growth. [ABSTRACT FROM AUTHOR]