Thiosulfate/FeCl3 pre-treatment enhances short-chain fatty acid production and mitigates H2S generation during anaerobic fermentation of waste activated sludge: Performance, microbial community and ecological analyses.

Anaerobic fermentation (AF) has been identified as a promising method of transforming waste activated sludge (WAS) into high-value products (e.g., short-chain fatty acids (SCFAs)). This study developed thiosulfate/FeCl3 pre-treatment and investigated the effects of different thiosulfate/FeCl3 ratios (S:Fe = 3:1, 3:2, 1:1, 3:4 and 3:5) on SCFA production and sulfur transformation during the AF of WAS. At a S:Fe ratio of 1:1, the maximal SCFA yield (933.3 mg COD/L) and efficient H2S removal (96.5 %) were obtained. S:Fe ratios ≤ 1:1 not only benefited hydrolysis and acidification but largely mitigated H2S generation. These results were supported by the enriched acidogens and reduced sulfur-reducing bacteria (SRB). Molecular ecological network analysis further revealed that the keystone taxon (g_Saccharimonadales) was found in S:Fe = 1:1, together with reductions in associations among methanogens, acidogens and SRB. This work provides a strategy for enhancing high-value product recovery from WAS and minimising H2S emissions.

Cysteine and thiosulfate promoted cadmium immobilization in strain G303 by the formation of extracellular CdS.

Bacteria have evolved a variety of strategies to defend themselves against cadmium toxicity, however, the specific mechanisms involved in the enhancement of bacterial cadmium resistance by sulfur sources are unclear. In this study, a novel cadmium (Cd)-tolerant bacterium, Stenotrophomonas geniculata G303, was isolated from activated sludge. The growth of strain G303 under diverse Cd concentrations was investigated, and the minimum inhibitory concentration of Cd was found to be 1 mM. Strain G303 effectively remove 94.7 % of Cd after 96 h of culture. Extracellular CdS was detected using multiple methods, with the CdS formed being aggregated in the biofilm. The addition of cysteine and thiosulfate to the medium significantly enhanced the Cd resistance and removal capacity of strain G303. Integrated genomic and proteomic analyses revealed that heavy metal transporters cooperate to resist Cd stress. Cysteine and thiosulfate improved Cd tolerance in strain G303 by upregulating nitrogen and energy metabolism. Proteins associated with nitrate reduction likely played a pivotal role in cysteine and thiosulfate metabolism. Notably, cysteine synthase and the SUF system played crucial roles in CdS formation. This study systematically explored the impact of cysteine and thiosulfate on the Cd resistance of strain G303, deepening our understanding of the microbial response mechanism to heavy metals.

Structural and functional characterization of sulfurtransferase from Frondihabitans sp. PAMC28461.

Sulfurtransferases transfer of sulfur atoms from thiols to acceptors like cyanide. They are categorized as thiosulfate sulfurtransferases (TSTs) and 3-mercaptopyruvate sulfurtransferases (MSTs). TSTs transfer sulfur from thiosulfate to cyanide, producing thiocyanate. MSTs transfer sulfur from 3-mercaptopyruvate to cyanide, yielding pyruvate and thiocyanate. The present study aimed to isolate and characterize the sulfurtransferase FrST from Frondihabitans sp. PAMC28461 using biochemical and structural analyses. FrST exists as a dimer and can be classified as a TST rather than an MST according to sequence-based clustering and enzyme activity. Furthermore, the discovery of activity over a wide temperature range and the broad substrate specificity exhibited by FrST suggest promising prospects for its utilization in industrial applications, such as the detoxification of cyanide.

Enhancing the bioreduction and interaction of arsenic and iron by thiosulfate in groundwater.

Thiosulfate influences the bioreduction and migration transformation of arsenic (As) and iron (Fe) in groundwater environments. The aim of this study was to investigate the impact of microbially-mediated sulfur cycling on the bioreduction and interaction of As and Fe. Microcosm experiments were conducted, including bioreduction of thiosulfate, As(V), and Fe(III) by Citrobacter sp. JH012-1, as well as the influence of thiosulfate input at different initial arsenate concentrations on the bioreduction of As(V) and Fe(III). The results demonstrate that Citrobacter sp. JH012-1 exhibited strong reduction capabilities for thiosulfate, As(V), and Fe(III). Improving thiosulfate level promoted the bioreduction of Fe(III) and As(V). When 0, 0.1, 0.5, and 1 mM thiosulfate were added, Fe(III) was completely reduced within 9 days, 3 days, 1 day, and 0.5 days, simultaneously, 72.8%, 82.2%, 85.5%, and 90.0% of As(V) were reduced, respectively. The products of As(III) binding with sulfide are controlled by the ratio of As-S. When the initial arsenate concentration was 0.025 mM, the addition of thiosulfate resulted in the accumulation of soluble thioarsenite. However, when the initial arsenate level increased to 1 mM, precipitates of orpiment or realgar were formed. In the presence of both arsenic and iron, As(V) significantly inhibits the bioreduction of Fe(III). Under the concentrations of 0, 0.025, and 1 mM As(V), the reduction rates of Fe(III) were 100%, 91%, and 83%, respectively. In this scenario, the sulfide produced by thiosulfate reduction tends to bind with Fe(II) rather than As(III). Therefore, the competition of arsenic-iron and thiosulfate concentration should be considered to study the impact of thiosulfate on arsenic and iron migration and transformation in groundwater.

How to achieve adequate quenching for DBP analysis in drinking water?

Quenching is an important step to terminate disinfection during preparation of disinfected water samples for the analysis of disinfection byproducts (DBPs). However, an incomplete quenching might result in continued reactions of residual chlorine, whereas an excessive quenching might decompose target DBPs. Therefore, an adequate quenching to achieve simultaneous disinfection termination and DBP preservation is of particular importance. In this study, the two-stage reaction kinetics of chlorine and three commonly used quenching agents (i.e., ascorbic acid, sodium thiosulfate, and sodium sulfite) were determined. Stopping quenching during the first stage prevented interactions of residual chlorine with natural organic matter. Complete quenching was achieved by minimizing the quenching time for ascorbic acid and sodium sulfite, while limiting the quenching time to less than 3 min for sodium thiosulfate. At the optimized quenching times, the molar ratios (MRs) of quenching agent to chlorine were 1.05, 1.10, and 0.75 for ascorbic acid, sodium sulfite, and sodium thiosulfate, respectively. The destructive effects of the three quenching agents on total organic halogen (TOX) followed the rank order of ascorbic acid (33.7-64.8 %) < sodium sulfite (41.6-72.8 %) < sodium thiosulfate (43.3-73.2 %), and the destructive effects on aliphatic DBPs also followed the rank order of ascorbic acid (29.5-44.5 %) < sodium sulfite (34.9-51.9 %) < sodium thiosulfate (46.9-53.2 %). For total organic chlorine (TOCl) and aliphatic DBPs, the quenching behavior itself had more significant destructive effect than the quenching agent type/dose and quenching time, but for total organic bromine (TOBr), the destructive effect caused by quenching agent type/dose and quenching time was more significant. High-dose, long-duration quenching enhanced the reduction of TOX, but had little effect on aliphatic DBPs. Additionally, the three quenching agents reduced the levels of halophenols (except for tribromophenol), while maintained or increased the levels of tribromophenol, halobenzoic/salicylic acids, and halobenzaldehydes/salicylaldehydes. To achieve adequate quenching for overall DBP analysis in chlorinated water samples, it is recommended to use ascorbic acid at a quenching agent-to-chlorine MR of 1.0 for a quenching time of < 0.5 h.

Deep-sea in situ and laboratory multi-omics provide insights into the sulfur assimilation of a deep-sea Chloroflexota bacterium.

Chloroflexota bacteria are abundant and globally distributed in various deep-sea ecosystems. It has been reported based on metagenomics data that two deep-sea Chloroflexota lineages (the SAR202 group and Dehalococcoidia class) have the potential to drive sulfur cycling. However, the absence of cultured Chloroflexota representatives is a significant bottleneck toward understanding their contribution to the deep-sea sulfur cycling. In this study, we find that Phototrophicus methaneseepsis ZRK33 isolated from deep-sea sediment has a heterotrophic lifestyle and can assimilate sulfate and thiosulfate. Using combined physiological, genomic, proteomic, and in situ transcriptomic methods, we find that strain ZRK33 can perform assimilatory sulfate reduction in both laboratory and deep-sea conditions. Metabolism of sulfate or thiosulfate by strain ZRK33 significantly promotes the transport and degradation of various macromolecules and thereby stimulates the energy production. In addition, metagenomic results show that genes associated with assimilatory and dissimilatory sulfate reduction are ubiquitously distributed in the metagenome-assembled genomes of Chloroflexota members derived from deep-sea sediments. Metatranscriptomic results also show that the expression levels of related genes are upregulated, strongly suggesting that Chloroflexota bacteria may play undocumented roles in deep-sea sulfur cycling. IMPORTANCE: The cycling of sulfur is one of Earth's major biogeochemical processes and is closely related to the energy metabolism of microorganisms living in the deep-sea cold seep and hydrothermal vents. To date, some of the members of Chloroflexota are proposed to play a previously unrecognized role in sulfur cycling. However, the sulfur metabolic characteristics of deep-sea Chloroflexota bacteria have never been reported, and remain to be verified in cultured deep-sea representatives. Here, we show that the deep-sea Chloroflexota bacterium ZRK33 can perform sulfate assimilation in both laboratory and deep-sea conditions, which expands our knowledge of the sulfur metabolic potential of deep-sea Chloroflexota bacteria. We also show that the genes associated with assimilatory and dissimilatory sulfate reduction ubiquitously distribute in the deep-sea Chloroflexota members, providing hints to the roles of Chloroflexota bacteria in deep-sea sulfur biogeochemical cycling.

Evaluating the Effects of Kidney Preservation at 10 °C with Hemopure and Sodium Thiosulfate in a Rat Model of Syngeneic Orthotopic Kidney Transplantation.

Kidney transplantation is preferred for end-stage renal disease. The current gold standard for kidney preservation is static cold storage (SCS) at 4 °C. However, SCS contributes to renal graft damage through ischemia-reperfusion injury (IRI). We previously reported renal graft protection after SCS with a hydrogen sulfide donor, sodium thiosulfate (STS), at 4 °C. Therefore, this study aims to investigate whether SCS at 10 °C with STS and Hemopure (blood substitute), will provide similar protection. Using in vitro model of IRI, we subjected rat renal proximal tubular epithelial cells to hypoxia-reoxygenation for 24 h at 10 °C with or without STS and measured cell viability. In vivo, we preserved 36 donor kidneys of Lewis rats for 24 h in a preservation solution at 10 °C supplemented with STS, Hemopure, or both followed by transplantation. Tissue damage and recipient graft function parameters, including serum creatinine, blood urea nitrogen, urine osmolality, and glomerular filtration rate (GFR), were evaluated. STS-treated proximal tubular epithelial cells exhibited enhanced viability at 10 °C compared with untreated control cells (p < 0.05). Also, STS and Hemopure improved renal graft function compared with control grafts (p < 0.05) in the early time period after the transplant, but long-term function did not reach significance. Overall, renal graft preservation at 10 °C with STS and Hemopure supplementation has the potential to enhance graft function and reduce kidney damage, suggesting a novel approach to reducing IRI and post-transplant complications.

Comparative efficacy of sodium thiosulfate, bisphosphonates, and cinacalcet for the treatment of vascular calcification in patients with haemodialysis: a systematic review and network meta-analysis.

BACKGROUND: Up to now, there is no unequivocal intervention to mitigate vascular calcification (VC) in patients with hemodialysis. This network meta-analysis aimed to systematically evaluate the clinical efficacy of sodium thiosulfate, bisphosphonates, and cinacalcet in treating vascular calcification. METHODS: A comprehensive study search was performed using PubMed, Web of Science, the Cochrane Library, EMBASE and China National Knowledge Internet (CNKI) to collect randomized controlled trials (RCTs) of sodium thiosulfate, bisphosphonates, and cinacalcet for vascular calcification among hemodialysis patients. Then, network meta-analysis was conducted using Stata 17.0 software. RESULTS: In total, eleven RCTs including 1083 patients were qualified for this meta-analysis. We found that cinacalcet (SMD - 0.59; 95% CI [-0.95, -0.24]) had significant benefit on vascular calcification compared with conventional therapy, while sodium thiosulfate or bisphosphonates did not show such efficiency. Furthermore, as for ranking the efficacy assessment, cinacalcet possessed the highest surface under the cumulative ranking curve (SUCRA) value (88.5%) of lessening vascular calcification and was superior to sodium thiosulfate (50.4%) and bisphosphonates (55.4%). Thus, above results suggested that cinacalcet might be the most promising drug for vascular calcification treatment in hemodialysis patients. Mechanistically, our findings illustrated that cinacalcet reduced serum calcium (SMD - 1.20; 95% CI [-2.08, - 0.33]) and showed the tendency in maintaining the balance of intact Parathyroid Hormone (iPTH) level. CONCLUSIONS: This network meta-analysis indicated that cinacalcet appear to be more effective than sodium thiosulfate and bisphosphonates in mitigating vascular calcification through decreasing serum calcium and iPTH. And cinacalcet might be a reasonable option for hemodialysis patients with VC in clinical practice. SYSTEMATIC REVIEW REGISTRATION: [ http://www.crd.york.ac.uk/PROSPERO ], identifier [CRD42022379965].

First clinical evidence that trimethylsulfonium can serve as a biomarker for the production of the signaling molecule hydrogen sulfide.

BACKGROUND: Hydrogen sulfide (H2S) is established as the third gaseous signaling molecule and is known to be overproduced in down syndrome (DS) due to the extra copy of the CBS gene on chromosome 21, which has been suggested to contribute to the clinical manifestation of this condition. We recently discovered trimethylsulfonium (TMS) in human urine and highlighted its potential as a selective methylation metabolite of endogenously produced H2S, but the clinical utility of this novel metabolite has not been previously investigated. We hypothesize that the elevation of H2S production in DS would be reflected by an elevation in the methylation product TMS. METHODS: To test this hypothesis, a case-control study was performed and the urinary levels of TMS were found to be higher in the DS group (geo. mean 4.5 nM, 95 % CI 2.4-3.9) than in the control (N) group (3.1 nM, 3.5-6.0), p-value 0.01, whereas the commonly used biomarker of hydrogen sulfide, thiosulfate, failed to reflect this alteration in H2S production (15 µM (N) vs. 13 µM (DS), p-value 0.24. RESULTS: The observed association is in line with the proposed hypothesis and provides first clinical evidence of the utility of TMS as a novel and more sensitive biomarker for the endogenous production of the third gaseous signaling molecule than the conventionally used biomarker thiosulfate, which is heavily dependent on bacterial hydrogen sulfide production. CONCLUSION: This work shows that TMS must be explored in clinical conditions where altered metabolism of hydrogen sulfide is implicated.

Rapid start-up sulfur-driven autotrophic denitrification granular process: Extracellular electron transfer pathways and microbial community evolution.

Sulfur-driven autotrophic denitrification (SAD) granular process has significant advantages in treating low-carbon/nitrogen wastewater; however, the slow growth rate of sulfur-oxidizing bacteria (SOB) results in a prolonged start-up duration. In this study, the thiosulfate-driven autotrophic denitrification (TAD) was successfully initiated by inoculating anaerobic granular sludge on Day 7. Additionally, the electron donor was successfully transferred to the cheaper elemental sulfur from Day 32 to Day 54 at the nitrogen loading rate of 176.2 g N m-3 d-1. During long term experiment, the granules maintained compact structures with the α-helix/(ß-sheet + random coil) of 29.5-40.1 %. Extracellular electron transfer (EET) pathway shifted from indirect to direct when electron donors were switched thiosulfate to elemental sulfur. Microbial analysis suggested that thiosulfate improved EET involving enzymes activity. Thiobacillus and Sulfurimonas were dominant in TAD, whereas Longilinea was enriched in elemental sulfur-driven autotrophic denitrification. Overall, this strategy achieved in-situ enrichment of SOB in granules, thereby shortening start-up process.

Eliminating the need for preoperative intravenous hyperhydration: Sodium thiosulfate as nephrotoxicity prevention in HIPEC-treated patients - A retrospective analysis.

BACKGROUND: Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) is an effective treatment for peritoneal metastases. However, HIPEC with cisplatin is associated with renal toxicity. Sodium thiosulfate (ST) has been shown to prevent cisplatin-induced toxicity. METHODS: A retrospective, single-center analysis of patients treated curatively for peritoneal surface malignancy, who underwent cytoreductive surgery with cisplatin-based HIPEC between 2015 and 2020. Patients were categorized into three groups based on the management of cisplatin-induced renal toxicity: preoperative hyperhydration alone (PHH), preoperative hyperhydration with ST (PHH + ST), and ST alone. Renal function and complications, in terms of Acute (AKI) and chronic kidney injury (CKI), were monitored and analyzed during 3 postoperative months. RESULTS: This study included 220 consecutive patients. Mean serum creatinine levels were 95, 57 and 61 mmol/L, for PHH, PHH + ST and ST groups, respectively (p < 0.001). Glomerular Filtration Rate (GFR) were 96, 94 and 78 ml/min/1.73 m2, respectively (p < 0.001). AKI and CKI are respectively for PHH, PHH + ST and ST groups were 21 % (n = 46), 1 % (n = 2) and 0 % vs 19 % (n = 42), 0 % and 0 % (p < 0.001), for pairwise analysis did not show any difference between PHH + ST and ST alone combination, regarding nephrological outcomes. All patients were followed 3 months postoperatively. CONCLUSION: There is no need for preoperative hyperhydration when sodium-thiosulfate is used to prevent cisplatin-induced nephrotoxicity in patients undergoing cytoreductive surgery with HIPEC. These findings have implications for improving and simplifying the management of patients with peritoneal metastases undergoing HIPEC with cisplatin.

Sodium thiosulfate does not protect ovarian reserve from cisplatin-induced gonadotoxicity†.

Cisplatin, a platinum-containing alkylating agent, is used in the treatment of various tumors owing to its potent antitumor activity. However, it causes permanent and adverse effects, particularly hearing loss and depletion of ovarian reserve. Until recently, there were no clinically available protective agents to mitigate the adverse side effects of cisplatin-induced cytotoxicity. In 2022, sodium thiosulfate (STS) was approved by the Food and Drug Administration for mitigating hearing loss in children and adolescents undergoing cisplatin treatment. Consequently, our investigation aimed to determine if STS could protect ovarian reserve against cisplatin-induced gonadotoxicity. In an ex vivo culture, the cisplatin-only group exhibited a loss of primordial follicles, while post-STS administration after cisplatin exposure effectively protected primordial follicles. However, when post-STS was administrated either 6 or 4 h after cisplatin exposure, it did not confer protection against cisplatin-induced gonadotoxicity in postnatal day 7 or adolescent mouse models. Immunofluorescence assays using γH2AX and cPARP revealed that oocytes within primordial follicles exhibited DNA damage after cisplatin exposure, irrespective of post-STS administration. This underscores the rapid and heightened sensitivity of oocytes to gonadotoxicity. In addition, oocytes demonstrated an increased expression of pCHK2 rather than pERK, suggesting that the pathway leading to oocyte death differs from the pathway observed in the inner ear cell death following cisplatin exposure. These results imply that while the administration of STS after cisplatin is highly beneficial in preventing hearing loss, it does not confer a protective effect on the ovaries in mouse models.

Profound metabolic acidosis in association with sodium thiosulfate therapy in a patient with calcific uremic arteriolopathy: a case report and literature review.

Calciphylaxis, also known as Calcific uremic arteriolopathy (CUA), is a serious disorder that presents with skin necrosis due to calcification of dermal and subcutaneous adipose tissue capillaries and arterioles. The condition occurs primarily in patients with end-stage renal disease (ESRD) on dialysis, and it carries high morbidity and mortality, primarily due to sepsis, with an estimated six-month survival of approximately 50%. Although there are no high-quality studies to guide the optimal treatment approach for patients with calciphylaxis, many retrospective studies and case series support treatment with sodium thiosulfate (STS). Despite the frequent use of STS as an off-label treatment, data regarding its safety and efficacy are limited. STS has generally been considered a safe drug with mild side effects. However, severe metabolic acidosis associated with STS is a rare and life-threatening complication of STS treatment and is often unpredictable. Herein, we report a 64-year-old female with ESRD on peritoneal dialysis (PD) who presented with a profound high anion gap metabolic acidosis and severe hyperkalemia while on STS treatment for CUA. No other etiology for her severe metabolic acidosis other than STS was identified. ESRD patients receiving STS should be monitored closely for this side effect. Dose reduction, increasing the duration of infusion, or even discontinuing STS treatment should be considered if severe metabolic acidosis develops.

Ultra-stable mixotrophic denitrification coupled with anammox under organic stress for mainstream municipal wastewater treatment.

Sulfur-based autotrophic denitrification (SAD) coupled with anammox is a promising process for autotrophic nitrogen removal in view of the stable nitrite accumulation during SAD. In this study, a mixotrophic nitrogen removal system integrating SAD, anammox and heterotrophic denitrification was established in a single-stage reactor. The long-term nitrogen removal performance was investigated under the intervention of organic carbon sources in real municipal wastewater. With the shortening of hydraulic retention time, the nitrogen removal rate of the mixotrophic system dominated by the autotrophic subsystem reached 0.46 Kg N/m³/d at an organic loading rate of 0.57 Kg COD/m³/d, with COD and total nitrogen removal efficiencies of 82.5 % and 94 %, respectively, realizing an ideal combination of autotrophic and heterotrophic systems. The 15NO3--N isotope labeling experiments indicated that thiosulfate-driven autotrophic denitrification was the main pathway for nitrite supply accounting for 80.6 %, while anammox exhibited strong competitiveness for nitrite under the dual electron supply of sulfur and organic carbon sources and contributed to 65.1 % of nitrogen removal. Sludge granulation created differential functional distributions in different forms of sludge, with SAD showing faster reaction rate as well as higher nitrite accumulation rate in floc sludge, while anammox was more active in granular sludge. Real-time quantitative PCR, RT-PCR and high-throughput sequencing results revealed a dynamically changing community composition at the gene and transcription levels. The decrease in heterotrophic denitrification bacteria abundance indicated the effectiveness of the operational strategy for introduction of thiosulfate and maintaining the dominance of SAD in denitrification process in suppressing the excessive growth of heterotrophic bacteria in the mixotrophic system. The high transcriptional expression of sulfur-oxidizing bacteria (SOB) (Thiobacillus and Sulfurimonas) and anammox bacteria (Candaditus_Brocadia and Candidatus_Kuenenia) played a crucial role in the stable nitrogen removal.

Uncovering interactions among ternary electron donors of organic carbon source, thiosulfate and Fe0 in mixotrophic advanced denitrification: Proof of concept from simulated to authentic secondary effluent.

To offset the imperfections of higher cost and emission of CO2 greenhouse gas in heterotrophic denitrification (HDN) as well as longer start-up time in autotrophic denitrification (ADN), we synergized the potential ternary electron donors of organic carbon source, thiosulfate and zero-valent iron (Fe0) to achieve efficient mixotrophic denitrification (MDN) of oligotrophic secondary effluent. When the influent chemical oxygen demand to nitrogen (COD/N) ratio ascended gradually in the batch operation with sufficient sulfur to nitrogen (S/N) ratio, the MDN with thiosulfate and Fe0 added achieved the highest TN removal for treating simulated and authentic secondary effluents. The external carbon is imperative for initiating MDN, while thiosulfate is indispensable for promoting TN removal efficiency. Although Fe0 hardly donated electrons for denitrification, the suitable circumneutral environment for denitrification was implemented by OH- released from Fe0 corrosion, which neutralized H+generated during thiosulfate-driven ADN. Meanwhile, Fe0 corrosion consumed the dissolved oxygen (DO) and created the low DO environment suitable for anoxic denitrification. This process was further confirmed by the continuous flow operation for treating authentic secondary effluent. The TN removal efficiency achieved its maximum under the combination condition of influent COD/N ratio of 3.1-3.5 and S/N ratio of 2.0-2.1. Whether in batch or continuous flow operation, the coordination of thiosulfate and Fe0 maintained the dominance of Thiobacillus for ADN, with the dominant heterotrophic denitrifiers (e.g., Plasticicumulans, Terrimonas, Rhodanobacter and KD4-96) coexisting in MDN system. The interaction insights of ternary electron donors in MDN established a pathway for realizing high-efficiency nitrogen removal of secondary effluent.

Rates of iron(III) reduction coupled to elemental sulfur or tetrathionate oxidation by acidophilic microorganisms and detection of sulfur intermediates.

Bioleaching processes and acid mine drainage (AMD) generation are mainly driven by aerobic microbial iron(II) and inorganic sulfur/compound oxidation. Dissimilatory iron(III) reduction coupled to sulfur/compound oxidation (DIRSO) by acidophilic microorganisms has been described for anaerobic cultures, but iron reduction was observed under aerobic conditions as well. Aim of this study was to explore reaction rates and mechanisms of this process. Cell-specific iron(III) reduction rates for different Acidithiobacillus (At.) strains during batch culture growth or stationary phase with iron(III) (∼40 mM) as electron acceptor and elemental sulfur or tetrathionate as electron donor (1% or 5 mM, respectively) were determined. The rates were highest under anaerobic conditions for the At. ferrooxidans type strain with 6.8 × 106 and 1.1 × 107 reduced iron(III) ions per second per cell for growth on elemental sulfur and tetrathionate, respectively. The iron(III) reduction rates were somehow lower for the anaerobically sulfur grown archaeon Ferroplasma acidiphilum, and lowest for the sulfur grown At. caldus type strain under aerobic conditions (1.7 × 106 and 7.3 × 104 reduced iron(III) ions per second per cell, respectively). The rates for five strains of At. thiooxidans (aerobe) were in between those for At. ferrooxidans (anaerobe) and At. caldus (aerobe). There was no pronounced pH dependence of iron(III) reduction rates in the range of pH 1.0-1.9 for the type strains of all species but rates increased with increasing pH for four other At. thiooxidans strains. Thiosulfate as sulfur intermediate was found for At. ferrooxidans during anaerobic growths on tetrathionate and iron(III) but not during anaerobic growths on elemental sulfur and iron(III), and a small concentration was measured during aerobic growths on tetrathionate without iron(III). For the At. thiooxidans type strain thiosulfate was found with tetrathionate grown cells under aerobic conditions in presence and absence of iron(III), but not with sulfur grown cells. Evidence for hydrogen sulfide production at low pH was found for the At. ferrooxidans as well as the At. thiooxidans type strains during microaerophilic growth on elemental sulfur and for At. ferrooxidans during anaerobic growths on tetrathionate and iron(III). The occurrence of sulfur compound intermediates supports the hypothesis that chemical reduction of iron(III) ions takes place by sulfur compounds released by the microbial cells.

A retrospective review of outcomes after hyperbaric oxygen therapy for the treatment of calciphylaxis.

BACKGROUND: Calciphylaxis is a thrombotic vasculopathy characterized by painful necrotic ulcerations. There are no Food and Drug Administration approved therapies despite high mortality. OBJECTIVE: To compare mortality and wound healing outcomes in patients treated with hyperbaric oxygen therapy (HBOT) in addition to intravenous sodium thiosulfate (IV STS) versus patients who received IV STS only. Findings were stratified by dialysis status and modality. METHODS: 93 patients were included, with 57 patients in the control group (IV STS) and 36 patients in the treatment group (HBOT + IV STS). Mortality data were analyzed with traditional survival analyses and Cox proportional hazard models. Longitudinal wound outcomes were analyzed with mixed effects modeling. RESULTS: Univariate survival analyses showed that full HBOT treatment was associated with significantly (P = .016) longer survival time. Increasing number of HBOT sessions was associated with improved mortality outcomes, with 1, 5, 10 and 20 sessions yielding decreasing hazard ratios. There was also a significant (P = .042) positive association between increasing number of HBOT sessions and increased wound score. LIMITATIONS: Data collection was retrospective. CONCLUSION: HBOT may have a role in the treatment of calciphylaxis with benefits demonstrated in both mortality and wound healing. Larger prospective studies are needed to identify which patients would most benefit from this intervention.

Elemental sulfur enhances the anti-fungal effect of Lacticaseibacillus rhamnosus Lcr35.

Lacticaseibacillus rhamnosus Lcr35 is a well-known bacterial strain whose efficiency in preventing recurrent vulvovaginal candidiasis has been largely demonstrated in clinical trials. The presence of sodium thiosulfate (STS) has been shown to enhance its ability to inhibit the growth of Candida albicans strains. In this study, we confirmed that Lcr35 has a fungicidal effect not only on the planktonic form of C. albicans but also on other life forms such as hypha and biofilm. Transcriptomic analysis showed that the presence of C. albicans induced a metabolic adaptation of Lcr35 potentially associated with a competitive advantage over yeast cells. However, STS alone had no impact on the global gene expression of Lcr35, which is not in favor of the involvement of an enzymatic transformation of STS. Comparative HPLC and gas chromatography-mass spectrometry analysis of the organic phase from cell-free supernatant (CFS) fractions obtained from Lcr35 cultures performed in the presence and absence of STS identified elemental sulfur (S0) in the samples initially containing STS. In addition, the anti-Candida activity of CFS from STS-containing cultures was shown to be pH-dependent and occurred at acidic pH lower than 5. We next investigated the antifungal activity of lactic acid and acetic acid, the two main organic acids produced by lactobacilli. The two molecules affected the viability of C. albicans but only at pH 3.5 and in a dose-dependent manner, an antifungal effect that was enhanced in samples containing STS in which the thiosulfate was decomposed into S0. In conclusion, the use of STS as an excipient in the manufacturing process of Lcr35 exerted a dual action since the production of organic acids by Lcr35 facilitates the decomposition of thiosulfate into S0, thereby enhancing the bacteria's own anti-fungal effect.