Soil depth exerts a stronger impact on microbial communities and the sulfur biological cycle than salinity in salinized soils.

The distribution of microbial communities along salinity gradients in the surface layer of salinized soils has been widely studied. However, it is unknown whether microbial communities exhibit similar distribution patterns in surface and deep soils. Additionally, the relationship between soil depth, salinity, and sulfur metabolism remains unclear. Herein, bulk soils in the surface (S, 5-10 cm) and deep (D, 20-25 cm) layers from high- and low-salinity soils were analyzed using metagenomic and physicochemical analyses. Soil depth was significantly correlated to the concentration of sulfur compounds in the soil and exerted a stronger effect than salinity. Non-metric multidimensional scaling analysis revealed significant differences in microbial community structure with varying soil depths and salinities. However, soil depth clearly influenced microbial community abundance, homogeneity, and diversity, while salinity had a limited effect on microbial abundance. Archaea and bacteria were enriched in the surface and deep soils, respectively. Gene abundance analysis revealed significant differences in the abundance of sulfur-related genes at different soil depths. The abundance of sulfur oxidation genes was lower in deep soil than in surface soil, whereas the abundance of other sulfur-related genes showed the opposite trend. Redundancy analysis (RDA) showed that environmental factors and sulfur compounds have a significant impact on sulfur metabolism genes, with sulfide significantly affecting low-salinity soils in the surface and deep layers, whereas salinity and sulfane sulfur had a greater correlation with high-salinity soils. Correlation analysis further showed that Euryarchaeota clustered with Bacteroidetes and Balneolaeota, while Proteobacteria clustered with many phyla, such as Acidobacteria. Various sulfur metabolism genes were widely distributed in both clusters. Our results indicate that microorganisms actively participate in the sulfur cycle in saline soils and that soil depth can affect these processes and the structure of microbial communities to a greater extent than soil salinity.

Cupriavidus pinatubonensis JMP134 Alleviates Sulfane Sulfur Toxicity after the Loss of Sulfane Dehydrogenase through Oxidation by Persulfide Dioxygenase and Hydrogen Sulfide Release.

An incomplete Sox system lacking sulfane dehydrogenase SoxCD may produce and accumulate sulfane sulfur when oxidizing thiosulfate. However, how bacteria alleviate the pressure of sulfane sulfur accumulation remains largely unclear. In this study, we focused on the bacterium Cupriavidus pinatubonensis JMP134, which contains a complete Sox system. When soxCD was deleted, this bacterium temporarily produced sulfane sulfur when oxidizing thiosulfate. Persulfide dioxygenase (PDO) in concert with glutathione oxidizes sulfane sulfur to sulfite. Sulfite can spontaneously react with extra persulfide glutathione (GSSH) to produce thiosulfate, which can feed into the incomplete Sox system again and be oxidized to sulfate. Furthermore, the deletion strain lacking PDO and SoxCD produced volatile H2S gas when oxidizing thiosulfate. By comparing the oxidized glutathione (GSSG) between the wild-type and deletion strains, we speculated that H2S is generated during the interaction between sulfane sulfur and the glutathione/oxidized glutathione (GSH/GSSG) redox couple, which may reduce the oxidative stress caused by the accumulation of sulfane sulfur in bacteria. Thus, PDO and H2S release play a critical role in alleviating sulfane sulfur toxicity after the loss of soxCD in C. pinatubonensis JMP134.

[Distribution, structure and sequence alignment, and metagenomics analysis of two nitrite reductases with NO forming].

Objective: To reflect the importance of nitrite reductase (NIR) in the environment, we studied its distribution. Methods: The sequences of NIR were searched in the sequenced genome database at NCBI based on previous reported NIR sequences. The sequence similarity was done by multiple sequence alignment, and phylogenetic relationship was evaluated via constructing the phylogenetic tree. Furthermore, their distribution in the marine metagenome was studied by metagenomics. Results: The homologues of these two enzymes were 397 and 812 strains in sequenced genome, and the proportion was 8 and 15.7 percent, respectively. Almost all of archaea containing type II NIR. They have high identity by multiple sequence alignment analysis. The cofactor, the substrate and the cooper binding sites in type II were high conserved, suggesting that these enzymes had the specific function in denitrification. Phylogenetic analysis showed the two enzymes may have the common ancestor. In marine metagenome analysis, type I and II have 6 and 35 reads per 100000 reads, respectively, the two types of NIRs have the biggest proportion at the tropical south pacific area. Conclusion: Collectively, we suggested NIR, especially type II, play a key role in bioremediation of nitrogen contamination.

[Isolation and identification of a heterotrophic nitrifying and aerobic denitrifying Acinetobacter sp. YF14 and its denitrification activity].

OBJECTIVE: We separated, screened and identified a heterotrophic nitrifying and aerobic denitrifying bacterium from the surface sediment of a culture pool. Furthermore, we studied the role it plays in denitrification. METHODS: We separated the bacterium through enrichment culture, identified it by observing its morphological characteristics, studying its physiological and biochemical properties and making phylogenetic analysis of its 16S rDNA sequences. Then we studied the growth curve by regularly measuring the OD600 value, studied the influencing factors and optimum conditions of denitrification through orthogonal experiment, and examined its denitrification activity through interaction with the activated sludge of sewage treatment plant. RESULTS: The strain was identified as Acinetobacter and named A. sp. YF14, which is the first known Acinetobacter that carries out heterotrophic nitrification and aerobic denitrification. It reached the logarithmic growth phase after 12 hours, the stationary phase after 22 hours, and the decline phase after 45 hours. Using strain YF14 in a reactor under heterotrophic conditions, the NH+-N and total nitrogen removal rates reached 92% and 91% respectively within 3 days. In addition, nitrate and nitrite nitrogen were not observed during the incubation. Under aerobic incubation conditions, almost all of the nitrogen was removed through denitrification in the nitrate or nitrite culture medium inoculated with strain YF14. The orthogonal experiment results indicated that the denitrification effect was optimal when the rotate speed, carbon source, inoculation percentages, carbon nitrogen ratio and pH were 160 r/min, glucose, 1% , 8: 1 and 6. 5, respectively. Sorting Order of the factors on the denitrification effect was rotate speed > inoculation percentages > carbon source > carbon nitrogen ratio > pH. The strain YF14 could improve the denitrification rate by about 30% when interacting with active sludge. CONCLUSION: The strain YF14 coupling of heterotrophic nitrification and aerobic denitrification is feasible and is of practical value in water treatment.

Controlled crystallinity and crystallographic orientation of Cu nanowires fabricated in ion-track templates.

The hallmark of materials science is the ability to tailor the structures of a given material to provide a desired response. In this work, the structures involving crystallinity and crystallographic orientation of Cu nanowires electrochemically fabricated in ion-track templates have been investigated as a function of fabrication condition. Both single crystalline and polycrystalline nanowires were obtained by adjusting applied voltages and temperatures of electrochemical deposition. The anti-Hall-Petch effect was experimentally evidenced in the polycrystalline nanowires. The dominant crystallographic orientations of wires along [111], [100], or [110] directions were obtained by selecting electrochemical deposition conditions, i.e., H(2)SO(4) concentration in electrolyte, applied voltage, and electrodeposition temperature.