A two-parameter model for the determination of the partition coefficient for TRS in a culture medium

A two-parameters model was applied for the determination of the activity coefficient for a culture medium, and compared with Henry's law, the extended UNIQUAC, and experimental data obtained from an experimental setup system, consisting of a liquid culture media Thiobacillus (ATCC 290) with hydrogen sulfide (H2S), dimethyl sulfide (DMS), methyl mercaptan (MM), and dimethyl disulfide (DMDS), respectively. The ANOVA indicates that the use of Henry's law is not appropriate for MM and H2S with R2adj values of -106.15% and -53.33%, respectively. The extended UNIQUAC model and the two-parameter model were able to describe the system with values of 76.94% and 94.15% for DMS and DMDS in the case of UNIQUAC Extended, respectively, and 88.50% and 98.08% using the two-parameter model. These results show that the two-parameter model is able to describe the system, using a low number of parameters. However, the extended UNIQUAC shows better results but presenting a high level of over-parameterization. Henry's law showed significant deviations, not being representative of all analyzed cases. The two-parameter model is presented as an alternative to describing systems in which vapor-liquid mass transfer is involved in culture media, providing a better approximation than traditional models and lower calculation costs than complex models.

Co-Treatment with Single and Ternary Mixture Gas of Dimethyl Sulfide, Propanethiol, and Toluene by a Macrokinetic Analysis in a Biotrickling Filter Seeded with Alcaligenes sp. SY1 and Pseudomonas Putida S1

The biotrickling filter (BTF) treatment is an effective way of dealing with air pollution caused by volatile organic compounds (VOCs). However, this approach is typically used for single VOCs treatment but not for the mixtures of VOC and volatile organic sulfur compounds (VOSCs), even if they are often encountered in industrial applications. Therefore, we investigated the performance of BTF for single and ternary mixture gas of dimethyl sulfide (DMS), propanethiol, and toluene, respectively. Results showed that the co-treatment enhanced the removal efficiency of toluene, but not of dimethyl sulfide or propanethiol. Maximum removal rates (rmax) of DMS, propanethiol and toluene were calculated to be 256.41 g·m−3·h−1, 204.08 g·m−3·h−1 and 90.91 g·m−3·h−1, respectively. For a gas mixture of these three constituents, rmax was measured to be 114.94 g·m−3·h−1, 104.17 g·m−3·h−1 and 99.01 g·m−3·h−1, separately. Illumina MiSeq sequencing analysis further indicated that Proteobacteria and Bacteroidetes were the major bacterial groups in BTF packing materials. A shift of bacterial community structure was observed during the biodegradation process.

Simultaneous biodegradation of dimethyl sulfide and 1-propanethiol by Pseudomonas putida S-1 and Alcaligenes sp. SY1: “Lag” cause, reduction and kinetics exploration

Simultaneous biodegradation of malodorous 1-propanethiol (PT) and dimethyl sulfide (DMS) inoculated with Pseudomonas putida S-1 and Alcaligenes sp. SY1 were investigated and interactions implicated were explored. Results showed that PT was completely degraded in 33 h, while a lag of 10 h was observed for DMS degradation alone, and the lag even extended to 81 h in the binary mixture. Mechanism analysis found that the lag was mainly attributed to the exposure of DMS degrader (Alcaligenes sp. SY1), rather than PT metabolites and PT degrader. The exposure time and PT concentration influenced the lag duration much. Citric acid could effectively reduce the lag. Pseudo first-order model was proved suitable for the description of PT degradation, revealing that PT degradation could be enhanced in presence of DMS regardless of its concentration. A modified Gompertz model, incorporated the lag phase, was developed for the description of DMS degradation in the mixture, revealing that DMS degradation depended on the initial PT concentration. When the lag was not considered, PT with low-concentration could promote DMS biodegradation, while a higher concentration (＞20 mg·L−1) cast negative effect.

Novel Insights into Dimethylsulfoniopropionate Catabolism by Cultivable Bacteria in the Arctic Kongsfjorden

Dimethylsulfoniopropionate (DMSP) is one of the most abundant organic sulfur compounds in the oceans, which is mainly degraded by bacteria through two pathways, a cleavage pathway and a demethylation pathway. Its volatile catabolites dimethyl sulfide (DMS) and methanethiol (MT) in these pathways play important roles in the global sulfur cycle and have potential influences on the global climate. Intense DMS/DMSP cycling occurs in the Arctic. However, little is known about the diversity of cultivable DMSP-catabolizing bacteria in the Arctic and how they catabolize DMSP. Here, we screened DMSP-catabolizing bacteria from Arctic samples and found that bacteria of four genera ( Psychrobacter , Pseudoalteromonas , Alteromonas and Vibrio ) could grow with DMSP as the sole carbon source, among which Psychrobacter and Pseudoalteromonas are predominant. Four representative strains ( Psychrobacter sp. K31L, Pseudoalteromonas sp. K222D, Alteromonas sp. K632G and Vibrio sp. G41H) from different genera were selected to probe their DMSP catabolic pathways. All these strains produce DMS and MT simultaneously during their growth on DMSP, indicating that all strains likely possess the two DMSP catabolic pathways. On the basis of genomic and biochemical analyses, the DMSP catabolic pathways in these strains were proposed. Bioinformatic analysis indicated that most bacteria of Psychrobacter and Vibrio have the potential to catabolize DMSP via the demethylation pathway, and that only a small portion of Psychrobacter strains may catabolize DMSP via the cleavage pathway. This study provides novel insights into DMSP catabolism in marine bacteria. IMPORTANCE Dimethylsulfoniopropionate (DMSP) is abundant in the oceans. The catabolism of DMSP is an important step of the global sulfur cycle. Although Gammaproteobacteria are widespread in the oceans, the contribution of Gammaproteobacteria in global DMSP catabolism is not fully understood. Here, we found that bacteria of four genera belonging to Gammaproteobacteria ( Psychrobacter , Pseudoalteromonas , Alteromonas and Vibrio ), which were isolated from Arctic samples, were able to grow on DMSP. The DMSP catabolic pathways of representative strains were proposed. Bioinformatic analysis indicates that most bacteria of Psychrobacter and Vibrio have the potential to catabolize DMSP via the demethylation pathway, and that only a small portion of Psychrobacter strains may catabolize DMSP via the cleavage pathway. Our results suggest that novel DMSP dethiomethylases/demethylases may exist in Pseudoalteromonas , Alteromonas and Vibrio , and that Gammaproteobacteria may be important participants in marine, especially in polar DMSP cycling.

Oceanic emissions of dimethyl sulfide and methanethiol and their contribution to sulfur dioxide production in the marine atmosphere

Oceanic emissions of dimethyl sulfide (CH3SCH3, DMS) have long been recognized to impact aerosol particle composition and size, the concentration of cloud condensation nuclei (CCN), and Earth’s radiation balance. The impact of oceanic emissions of methanethiol (CH3SH, MeSH), which is produced by the same oceanic precursor as DMS, on the volatile sulfur budget of the marine atmosphere is largely unconstrained. Here we present direct flux measurements of MeSH oceanic emissions using the eddy covariance (EC) method with a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToFMS) detector and compare them to simultaneous flux measurements of DMS emissions from a coastal ocean site. Campaign mean mixing ratios of DMS and MeSH were 72 ppt (28–90 ppt interquartile range) and 19.1 ppt (7.6–24.5 ppt interquartile range) respectively. Campaign mean (and interquartile range) emission fluxes of DMS (FDMS) and MeSH (FMeSH) were 1.13 (0.53–1.61) and 0.21 (0.10–0.31) ppt m s-1 respectively. Linear least squares regression of observed MeSH and DMS flux indicates the emissions are highly correlated with each other (R2 = 0.65) over the course of the campaign, consistent with a shared oceanic source. The campaign mean DMS to MeSH flux ratio (FDMS:FMeSH) was 5.5 ± 3.0 calculated from the ratio of 304 individual coincident measurements of FDMS and FMeSH. Measured FDMS:FMeSH was weakly correlated (R2 = 0.15) with ocean chlorophyll concentrations, with FDMS:FMeSH reaching a maximum of 10.8 ± 4.4 during a phytoplankton bloom period. No other volatile sulfur compounds were observed by PTR-ToFMS to have a resolvable emission flux above their flux limit of detection or to have a gas phase mixing ratio consistently above their limit of detection during the study period, suggesting DMS and MeSH are the dominant volatile organic sulfur compounds emitted from the ocean at this site. The impact of this MeSH emission source on atmospheric budgets of sulfur dioxide (SO2) was evaluated by implementing observed emissions into a coupled ocean-atmosphere chemical box model using a newly compiled MeSH oxidation mechanism. Model results suggest that MeSH emissions lead to afternoon instantaneous SO2 production of 2.5 ppt hr-1, which accounts for 30 % of the instantaneous SO2 production in the marine boundary layer at the mean measured FDMS and FMeSH. This contribution of MeSH to SO2 production is driven by a higher effective yield of SO2 from MeSH oxidation and the shorter oxidation lifetime of MeSH compared to DMS. This large additional source of marine SO2 has not been previously considered in global models of marine sulfur cycling. The field measurements and modeling results presented here demonstrate that MeSH is an important contributor to volatile sulfur budgets in the marine atmosphere, and must be measured along with DMS in order to constrain marine sulfur budgets. This large additional source of marine reduced sulfur from MeSH will contribute to particle formation and growth and CCN abundance in the marine atmosphere, with subsequent impacts on climate.