Amino acids in yeast fermentation: A review of their roles from nutrients to modulators.

Denitrifiers contribute to the remediation of agriculturally impacted aquifers by using NO3⁻ as an electron acceptor. However, the effects of local hydrogeochemical factors (e.g. O2, electron donors, carbon sources) on the abundance of denitrifiers remain poorly understood. To address this, we sampled planktonic (0.2-0.4µm, 0.4-8.0µm) and particle-associated (>8µm) biomass from eight groundwater wells and one karstic spring in the Ammer River catchment (SW Germany). Comparing groundwater hydrochemistry with microbial community composition, relative abundances of 16S rRNA and N-cycling gene copies (nirK, nirS, amoA) showed that declining O2 and dissolved organic carbon along the aquifer corresponded to lower bacterial and archaeal 16S rRNA gene copy numbers. Despite oxic conditions in the recharge zone, NO3⁻ can be reduced heterotrophically and autotrophically in anoxic microniches. In the confined anoxic zone, taxa such as Aquabacterium, Acidovorax and Gallionella may couple NO3⁻ reduction to pyrite-derived Fe(II) oxidation. Microorganisms such as Rhodoferax, Sediminibacterium and Sulfurifustis may oxidize pyrite-derived reduced sulfur compounds. Hydrogen-oxidizing (e.g. Hydrogenophaga) and CH4-oxidizing microorganisms (e.g. Candidatus Methylomirabilis) may also contribute to NO3⁻ turnover. These findings suggest that NO3⁻ turnover in the carbonate aquifer shifts from predominantly organic matter-supported pathways in recharge groundwater towards increasing reliance on pyrite-derived electron donors under anoxic conditions.

Martian rocks are known to contain sulfur-bearing species, including sulfates and sulfides. These compounds record a sulfur cycle that operated over Mars' geological evolution. We used the Curiosity rover to investigate a deposit of light-toned stones in Gediz Vallis, within Gale crater on Mars. We find that the stones are composed of native sulfur. The sulfur deposit appears to have formed in place, within a sinuous entrenched canyon cut into the floor of Gediz Vallis. The presence of native sulfur implies that a sulfur enrichment pathway involving buoyant subsurface fluids operated on ancient Mars. We propose that the primary source of this sulfur was magmatic vapor, which cooled in the near subsurface cryosphere and was released by decompression during the erosion of Gediz Vallis.

Electrode potentials influence the generation and fate of volatile sulfur compounds from sludge anaerobic digestion via microbial extracellular electron transfer.

MMSE-GC-MS volatile organic compound profiling of twelve defect categories in Robusta coffee beans: chemical markers and multivariate discrimination of quality defects.

Gandhak-ki-baoli, an ancient stepwell, long revered for its therapeutic properties, represents untapped natural reservoir of bioavailable sulfur and bioactive compounds. In this study a multidisciplinary analytical approach was employed to investigate the physicochemical and biochemical characteristics of stepwell water and its surrounding geological matrix. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) revealed a notable concentration of sulfur (~61 ppm) in the rock samples, while water profiling confirmed a mineral-rich composition indicative of redox-influenced hydrochemical environment. Ultra Performance Liquid Chromatography coupled with Electrospray Ionization and Quadrupole-Time-of-Flight-Mass-Spectrometry (UPLC–ESI–QToF–MS) identified 20 bioactive compounds exhibiting antimicrobial, antioxidant, and anti-inflammatory properties. Therapeutic potential is attributed to (1) membrane-permeabilizing saponins, such as digitonin, which may enhance the permeation of mineral and bioactive compounds through epidermal layers, and (2) bioactive phenolics and flavonoids, such as coumarin, capable of deep dermal absorption. These findings offer a detailed chemical and metabolomic profile of this historic stepwell, underscoring its significance as a unique reservoir with potential biological relevance and applications that warrant further investigation.

Despite the importance of the oxidation of reduced sulfur compounds in the biogeochemical sulfur cycle and climate, the mechanism of the transformation of methanethiol (CH3SH), the second highest gas-phase marine sulfur emission besides dimethyl sulfide, remains weakly explored. This work presents an investigation of the reaction of CH3SH with hydroxyl radicals (˙OH) and chlorine atoms (Cl˙) using the DLPNO-CCSD(T)/aug-cc-pVTZ//M06-2X/aug-cc-pV(T+d)Z method, both in the absence and presence of water. The results indicate that the hydrogen abstraction by ˙OH/Cl˙ from the -SH group is more favored than from the -CH3 group, leading to the formation of CH3S˙ and ˙CH2SH radicals, respectively, and HCl. While HCl is known to participate in tropospheric physicochemical processes, the fates of CH3S˙ and ˙CH2SH radicals were further examined. Their reactions with O2 lead to and H2CS formation while reactions with NO2 indicate fast formation of HONO and H2CS. Moreover, the CH3S˙ reaction with O2 also forms though at a relatively lower rate than The overall rate coefficients for CH3SH + ˙OH and CH3SH + Cl˙ reactions at 298 K were determined to be 1.69 × 10-11 and 7.49 × 10-10 cm3 per molecule per s, respectively, and were found to exhibit a negative temperature dependency in the temperature range 260-360 K. Besides its contribution to atmospheric sulfate, this study highlights the potential influence of CH3SH on the atmospheric oxidative capacity through HONO and formation, and the necessity to fully assess its chemistry and the contribution thereof to atmospheric chemistry.

Archaeal extrachromosomal elements (ECEs) are arguably the least well understood of all genetic elements, and few have >200 kbp (jumbo) genomes. Here, we report circular, jumbo ECEs with genomes of up to 535 kbp in length that associate with anaerobic methane-oxidizing Methanoperedens archaea. Notably, a 409-kbp genome related to jumbo ECEs is integrated into a subset of the ~4.2 Mbp Methanoperedens chromosomes at the tRNA-Asp genes. This represents the largest integrative element in Archaea and supports the jumbo ECE-host association. Multiple genome alignments and phylogenetic analyses suggest that the large ECE sizes developed by extensive DNA acquisition from Methanoperedens. The newly identified ECEs encode, and in some cases express, metabolic genes such as tetrahydromethanopterin S-methyltransferase exclusively involved in methane metabolism, and genes for nitrogen and sulfur compound transformations. Also encoded are defense systems, some of which are absent in hosts, such as hybrid Type I/Type III-A CRISPR-Cas systems. In contrast to viruses and plasmids, they have host-like replication machinery and occur at stable copy ratios of 1.44 ± 0.24:1 to the host. Overall, our results reveal a spectrum of jumbo ECEs of Methanoperedens, ranging from plasmid-like to minichromosome-like.

Solar geoengineering with sulfuric acid aerosols in the lower stratosphere might be used to reduce the impacts of climate change. Almost all studies have assumed sulfur is transported aloft as sulfur dioxide; several other sulfur compounds are plausible. We evaluated elemental sulfur (S8), hydrogen sulfide (H2S), sulfur dioxide (SO2), carbon disulfide (CS2), sulfur trioxide (SO3), and sulfuric acid (H2SO4), examining the mechanisms of dispersal in liquid form, safety, and costs for materials supply and deployment with a 20 km altitude aircraft. Levelized, combined costs for material production and lofting at 100 ktonne/year scale range from $1140 to $5150/tonne-S. We find that the cost to loft H2S is about half that of SO2, but the production cost of H2S is more uncertain and could be high enough to change this conclusion. The additional oxidation step required for H2S adds <20% to the aerosol formation time scale, so H2S and SO2 should produce similar aerosol size distributions if new particle formation is negligible. H2S and SO2 have high and roughly equivalent toxicity. H2S presents a further flammability risk that SO2 does not. S8 would be much safer than H2S or SO2, but it requires airborne combustor technology that is not yet developed. CS2 is not preferred on any metric. SO3 and H2SO4 are ∼4 times more expensive than H2S to loft but offer additional control over the aerosol size distribution that will likely reduce some side effects of sulfuric acid aerosol geoengineering.

This study assessed the feasibility of remote halitosis diagnosis by evaluating VSC stability over 7 days and their association with periodontal parameters. One hundred adult patients attending a periodontal examination were included. Oral gas samples were collected using plastic syringes and analyzed by gas chromatography (OralChroma) at baseline (D0) and after 7 days of storage at room temperature (D7). Hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and dimethyl sulfide ((CH3)2S) were quantified. Periodontal parameters were recorded. Correlations and agreement analyses were performed. At D0, 64% and 31% of patients were classified as having halitosis using thresholds of > 120 ppb and > 300 ppb, respectively. Mean VSC concentrations were 10.2 (33.1) ppb for H2S, 208.3 (443.2) ppb for CH3SH, and 79 (166) ppb for (CH3)2S, and increased after 7 days of storage for all compounds except H2S. Only (CH3)2S showed a significant correlation between D0 and D7 measurements. Agreement between halitosis diagnoses at D0 and D7 was poor for both thresholds (Cohen's kappa < 0.2). Associations between VSC levels and periodontal parameters were weak. Delayed analysis of oral gas samples significantly altered VSC measurements limiting their reliability for remote halitosis diagnosis. Periodontal parameters were not strongly associated with VSC levels.

This study systematically investigated the flavor contribution of sulfur compounds to the soy sauce flavor Baijiu ( SSFB) by integrating traditional flavor analysis with machine learning methods. A total of 88 sulfur compounds were identified through the comprehensive two-dimensional gas chromatography-hydrogen sulfide chemiluminescence detector. The significant flavor contribution was confirmed by orthogonal partial least squares-discriminant analysis and odor activity value, and correlation analysis revealed their systematic associations with 8 aroma notes. Eight core sulfur compounds were screened in combination with 7 machine learning methods. The double matrix addition experiment demonstrated these compounds significantly enhanced the jiang and chen aroma. Notably, the study revealed the matrix-dependent flavor regulation of sulfur compounds. In young SSFB, these compounds simultaneously enhanced the jiang and chen aroma along with floral and fruity notes, while in aged SSFB, they acted more specifically to intensify the core jiang and chen aroma, with a reduced contribution to others.

The microbial cycling of dimethylsulfoniopropionate (DMSP) and dimethyl sulfide (DMS) constitutes a crucial component of the global sulfur cycle, influencing climate regulation through the release of climate-active gases. Since DMSP production has historically been attributed to planktonic algae, research on its cycling has consequently centered on the surface ocean. However, the continuous discovery of bacterial DMSP synthesis genes (dsyB, mmtN, and dsyGD) has confirmed that the DMSP/DMS cycling process may also exist in the aphotic deep-sea environment. Further supporting this, the recently identified hydrogen sulfide (H2S)/methanethiol (MeSH)-dependent DMS-producing enzyme MddH, widespread among marine bacteria, may represent a significant source of DMS. This review integrates emerging insights into the ecological roles, environmental distribution, and microbial metabolism of these organic sulfur compounds, with a specific emphasis on deep-sea environments. We further discuss the distribution of key microbial taxa and functional genes involved in the biosynthesis and degradation of DMSP and DMS across deep-sea water columns and sediments. Collectively, this review highlights the existence of an active microbial DMSP/DMS cycling network in the deep ocean that remained overlooked until recently, with profound implications for global biogeochemical cycles and climate.

Multi-platform metabolomics reveals lipid remodeling during fruit development and aroma emergence in ripening durian (Durio zibethinus L.).

In the current study, the effects of chitosan coatings combined with thyme or rosemary essential oils (EOs), applied as natural antifungal agents to prevent superficial fungal growth on the surface of sucuk, were investigated throughout the ripening period in terms of lipolytic, proteolytic, and oxidative changes, as well as volatile composition and sensory properties. Six sucuk groups were produced by covering the casing surface on day 4 of production with distilled water (DW), acetic acid (AA), potassium sorbate (PS), chitosan (C), chitosan+thyme EO (CT), or chitosan+rosemary EO (CR). Superficial fungal growth was reduced approximately 4-log units in chitosan+EO treatments compared to the control. The lowest fungal count (log CFU/cm2) was observed in PS-treated sucuk (0.60), followed by CT (2.06) and CR (2.09), whereas this value was 5.95 in the DW group (p<0.05). Coatings containing EOs retarded lipid oxidation as well as free fatty acid (FFA) formation, as the lowest values were recorded in the CT and CR groups, with FFA contents of 4.75% and 4.96% and thiobarbituric acid reactive substances values of 0.60 and 0.60 mg MA/kg, respectively. The lowest sulfhydryl reduction (32%) was also observed in the CT and CR groups, compared to the PS, in which the reduction was 39% (p<0.05). The fatty acid profile and sensory properties of the sausages were not adversely affected by the superficial chitosan-EO coatings. A total of 46 and 67 volatile compounds were identified in sausages and casings, respectively. The major volatile constituents of sucuk in the CT and CR groups were acids, terpenes, sulfur compounds, and aldehydes, accounting for 10.41-17.07%, 58.89-66.88%, 5.36-6.70%, and 12.68-12.85% of the total volatile composition, respectively. In conclusion, CT or CR coating can be considered an alternative antifungal approach to synthetic treatments for preventing superficial fungal growth without adversely affecting the characteristic quality properties of sucuk.

The interactions of nitric oxide with intracellular redox status and the influence of molecular hydrogen.

How volatile sulfur compounds reshape soybean protein: From multiscale molecular binding mechanism study to emulsion system design

From multiphase redistribution to emission control: deciphering iron-mediated interactions in sulfur dynamics during sludge anaerobic digestion.

Organic sulfur metabolism drives volatile sulfur compound generation during wastewater treatment plant sludge thickening.

Evaluation of measurement uncertainty for trace-level sulfur compounds analysis in fuel hydrogen using pre-concentration sulfur chemiluminescence detector gas chromatography

Periodontal disease (PD) is one of the most common infectious conditions in dogs, associated with plaque accumulation, gingival inflammation, halitosis, and tooth loss. Halitosis is primarily caused by volatile sulfur compounds (VSCs) generated by anaerobic bacteria, including Porphyromonas gulae (P. gulae), a pathogen closely linked to PD progression. This study examined the effects of oral interferon alpha (IFN-α) on halitosis and bacterial activity in dogs with PD. Thirty-two dogs with moderate-to-severe PD were enrolled and allocated to untreated controls (n = 10) or IFN-α treatment (n = 22). Dogs in the treatment group received 2.75 g of IFN-α formulation (InterBerryα®) applied to the gingival margin twice weekly for five weeks. Clinical outcomes included PD Severity Index, enzymatic activity to hydrolyze N-benzoyl-DL-arginine-naphthylamide (BANA), PCR detection of P. gulae, and halitosis evaluation by gas chromatography and pet owner assessment. IFN-α significantly reduced PD Severity Index, BANA activity, and VSC concentrations (hydrogen sulfide and methyl mercaptan) compared with baseline and controls. Additionally, 27% of treated dogs converted to P. gulae-negative status after therapy. Owners reported marked improvement in oral malodor. These findings suggest that oral IFN-α effectively alleviates halitosis and reduces periodontal pathogen activity, supporting its potential as a non-invasive treatment for canine PD.