Biomineralization of heavy metals based on urea transport and hydrolysis within a new bacterial isolate, B. intermedia TSBOI.

A newly isolated ureolytic bacteria, Brucella intermedia TSBOI, exhibited microbially induced calcite precipitation (MICP) which is a promising technique for the remediation of heavy metals in polluted environments. Brucella intermedia TSBOI achieved 90-100% removal of 1 mmol/L Cu2+/Pb2+/Zn2+ within 72 h. A distinctive feature lies in B. intermedia TSBOI's capacity for the transport and hydrolysis of urea, considered to be critical for its strong urease activity. This study explored the mechanisms of this capacity at the genetic, molecular and protein levels through complete genome sequencing, molecular docking and enzymatic reaction kinetics. The results revealed that, for urea hydrolysis, B. intermedia TSBOI exhibited a comprehensive urease gene cluster, with the key gene ureC demonstrating an absolute expression level approximating to 4 × 104 copies/RNA ng under optimal conditions. Results also confirmed the strong spontaneous, energy-independent binding ability of it's urease to urea, with the lowest Gibbs free energy binding site linking to the three amino acids, alanine, asparagine and serine. The urea transport gene yut presented and expressed, with the absolute expression enhanced in response to increasing urea concentrations. The significant positive correlation between ureC/yut expression levels and urease activity provided a theoretical basis for B. intermedia TSBOI's heavy metal bioremediation potential. ENVIRONMENTAL IMPLICATION: Heavy metals (Cu, Pb and Zn) were studied in this study. Heavy metals are hazardous due to their toxicity, persistence, and ability to bioaccumulate in living organisms. They can cause severe health issues, harm ecosystems, and contaminate air, water, and soil. A novel ureolytic bacteria, Brucella intermedia TSBOI, exhibited microbially induced carbonate precipitation capability was isolated which removed 90-100% of 1 mmol/L Cu2+/Pb2+/Zn2+ within 72 h. Its advantages in urea hydrolysis and transport facilitate the remediation of actual heavy metal contaminated environments.

Exploring the synergistic interplay of sulfur metabolism and electron transfer in Cr(VI) and Cd(II) removal by Clostridium thiosulfatireducens: Genomic and mechanistic insights.

In this study, a sulfate-reducing bacterium, Clostridium thiosulfatireducens (CT) was reported and the performance and removal mechanism of Cr(VI) and Cd(II) removal were investigated. It is noteworthy that the dsrAB gene is absent in this strain, but the strain is capable of producing sulfide. The conversion rate of Cr(VI) by CT was 84.24 % at a concentration of 25 mg/L, and the conversion rate of Cd(II) was 94.19 % at a concentration of 28 mg/L. The complete genome is 6,106,624 bp and the genome consisted of a single chromosome. The GC content of the chromosomes was 29.65 %. The mechanism of heavy metal removal by CT bacteria mainly includes biosorption, electron transfer and redox, with reduction combined with S2- precipitation as the main pathway. The product characterization results showed that the formation of mainly ionic crystals and precipitates (CdS, Cd(OH)2, Cr(OH)3, Cr2O3) after adsorption. Genome-wide techniques have shown that the clearance of Cr(VI) and Cd(II) by CT is largely dependent on sulfate transport, sulfur metabolism, and energy metabolism to some extent. In addition, genes related to ATP binding, electron carrier activity, transporter protein genes, and DNA repair are also important factors to improve the heavy metal resistance and transformation ability of CT strains. Both the Fe-S cycle and the ROS-resistant system can enhance the electron transfer activity and thus slow down the damage of heavy metals to microorganisms. This study fills the gap in the understanding of the basic properties and heavy metal transformation mechanism of CT.

Mechanisms of microbial-driven changes in soil ecological stoichiometry around gold mines.

In this study, we used soils with different pollution and nutrient levels (non-polluted S1, highly polluted low-nutrient S2, and highly polluted high nutrient S3) around the gold mine tailing ponds, and combined with metabolic limitation modeling and macro-genomics approaches, aiming to investigate the relationship between soil microbial composition and soil eco-chemometrics characteristics under heavy metal stress. The results showed that heavy pollution resulted in reduced SOC, TN, microbial biomass, and with C- and P- acquisition (BG, CBH, ALP) as well as nitrogen limitation of soil microbial metabolism in soils (S2, S3). Further analysis by macrogenomics showed that heavy metal contamination led to an increase in α-microbial diversity and altered the composition of microbial communities in the soil. The cycling of C, N, and P nutrients was altered by affecting the relative abundance of Anaeromyxobacter, Steroidobacter, Bradyrhizobium, Acidobacterium, Limnochorda (predominantly in the Ascomycetes and Acidobacteria phyla), with the most pronounced effect on the composition of microorganisms synthesizing C-acquiring enzymes, and heavy metals and pH were the main influences on ecological stoichiometry. The results of this study are useful for understanding the sustainability of ecological remediation in heavy metal contaminated areas and for developing ecological restoration strategies.

Risk factors of pancreatitis after endoscopic retrograde cholangiopancreatography in patients with biliary tract diseases.

BACKGROUND: To investigate the risk factors of pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP) in patients with biliary tract diseases. METHODS: We retrospectively analyzed the clinical data of 480 patients who underwent ERCP for biliary tract diseases at the Affiliated Zhongshan Hospital of Dalian University from October 2011 to October 2016. The patients were divided into a study group (n = 75, with PEP) and a control group (n = 405, without PEP) based on whether they developed post-ERCP pancreatitis (PEP), and their clinical baseline data and intraoperative conditions were retrieved and compared. Then, factors associated with PEP were analyzed using logistic regression model, based on which a nomogram prediction model was constructed. The receiver operating characteristic (ROC) curve and calibration curve were used to evaluate the performance of the prediction model. RESULTS: Significant differences in age, sex, history of pancreatitis, history of choledocholithiasis, pancreatic duct imaging, pancreatic sphincterotomy, difficult cannulation, multiple cannulation attempts and juxtapapillary duodenal diverticula were observed between the two groups. Multivariate logistic regression analysis showed that age less than 60 years (OR, 0.477; 95% CI, 0.26-0.855), female sex (OR, 2.162; 95% CI, 1.220-3.831), history of pancreatitis (OR, 2.567; 95% CI, 1.218-5.410), history of choledocholithiasis (OR, 2.062; 95% CI, 1.162-3.658), pancreatic sphincterotomy (OR, 2.387; 95% CI, 1.298-4.390), pancreatic duct imaging (OR, 4.429; 95% CI, 1.481-13.242), multiple cannulation attempts (OR, 2.327; 95% CI, 1.205-4.493), difficult cannulation (OR, 2.421; 95% CI, 1.143-5.128), and JPD (OR, 2.002; 95% CI, 1.125-3.564) were independent risk factors for PEP. The nomogram for predicting the occurrence of PEP demonstrated an area under the ROC curve (AUC) of 0.787, and the calibration curves of the model showed good consistency between the predicted and actual probability of PEP. CONCLUSION: Our results showed that age less than 60 years, female sex, history of pancreatitis, history of choledocholithiasis, pancreatic sphincterotomy, pancreatic duct imaging, multiple cannulation attempts, difficult cannulation and juxtapapillary duodenal diverticula were independent risk factors for PEP. In addition, the established nomogram demonstrated promising clinical efficacy in predicting PEP risk in patients who underwent ERCP for biliary tract diseases.

Emodin Alleviates Intestinal Barrier Dysfunction by Inhibiting Apoptosis and Regulating the Immune Response in Severe Acute Pancreatitis.

OBJECTIVE: The intestinal barrier injury caused by severe acute pancreatitis (SAP) can induce enterogenous infection, further aggravating the inflammatory reactions and immune responses. This study aimed to test the hypothesis that emodin protects the intestinal function and is involved in the immune response in SAP. METHODS: The network pharmacology was established using the Swiss target prediction and pathway enrichment analysis. The SAP mice model was induced by cerulein (50 µg/kg) and lipopolysaccharide (10 mg/kg) hyperstimulation. The pharmacological effect of emodin in treating SAP was evaluated at mRNA and protein levels by various methods. RESULTS: The network analysis provided the connectivity between the targets of emodin and the intestinal barrier-associated proteins and predicted the BAX/Bcl-2/caspase 3 signaling pathway. Emodin alleviated the pathological damages to the pancreas and intestine and reduced the high concentrations of serum amylase and cytokines in vivo. Emodin increased the expression of intestinal barrier-related proteins and reversed the changes in the apoptosis-related proteins in the intestine. Simultaneously, emodin regulated the ratio of T helper type 1 (TH1), TH2, TH17, γδ T cells, and interferon γ/interleukin 17 producing γδ T cells. CONCLUSIONS: These findings partly verified the mechanism underlying the regulation of the intestinal barrier and immune response by emodin.

Phytoremediation potential of wheat intercropped with different densities of Sedum plumbizincicola in soil contaminated with cadmium and zinc.

Intercropping technology is applied widely in crop cultivation to help remediate soil polluted with heavy metals. To investigate the feasibility and potential of intercropping hyperaccumulator plants with crops in cadmium (Cd)- and zinc (Zn)-contaminated soil, a pot experiment was conducted to examine plant growth and the contents of Cd and Zn in the soil following intercropping of wheat and Sedum plumbizincicola. Five treatments were examined: control (wheat monoculture: 36 seedlings per pot), and intercropping of wheat with different planting densities of S. plumbizincicola (3, 6, 9 and 15 seedlings per pot, respectively). Results showed a decrease in soil pH, and in soil and wheat contents of Cd and Zn with increasing planting density of S. plumbizincicola, while the removal rate of Cd and Zn increased. Meanwhile, excessive planting (15 seedlings per pot) inhibited wheat growth by 27.34% compared with the control, and overall, the optimal planting density was 9 seedlings per pot, resulting in effective remediation with only a moderate effect on wheat growth. These findings highlight the value of intercropping S. plumbizincicola with wheat as a means of improving remediation of soil contaminated with heavy metals (Cd and Zn).

Effects of different types of humic acid isolated from coal on soil NH3 volatilization and CO2 emissions.

Humic acid can improve soil nutrients and promote plant growth. Weathered coal and lignite can be used as agricultural resources due to high humic acid content, but their impact on soil NH3 volatilization and CO2 emissions are yet to be determined. In this study, a field experiment was carried out to compare the effects of four types of humic acid isolated from coal (pulverized weathered coal (HC), pulverized lignite (HL), alkalized weathered coal (AC) and alkalized lignite (AL)) on NH3 volatilization, CO2 emissions, pH, the C/N ratio and enzyme activities in soil cultivated with maize. The effect of biotechnology humic acids (BHA) was also examined for comparison. HL, AC, AL and BHA all increased cumulative NH3 losses by 147.7, 278.5, 113.9, and 355.3%, respectively, compared with the control (chemical fertilizer only), and notably, BHA caused an increase of 90.71% compared with the humic acids isolated from coal. A significant increase in cumulative CO2 losses was observed only under AL treatment, by 14.44-24.90% compared with all other treatments. Soil urease activity was positively correlated with cumulative NH3 losses (P < 0.001), while the soil C/N ratio (P < 0.001) and soil sucrase activity (P < 0.05) were positively correlated with cumulative CO2 losses. Since humic acid from pulverized weathered coal caused no increase in NH3 volatilization or CO2 emissions, it is therefore thought to be the most suitable humic acid for field application.

Direct Formation of C-C Double-Bonded Structural Motifs by On-Surface Dehalogenative Homocoupling of gem-Dibromomethyl Molecules.

Conductive polymers are of great importance in a variety of chemistry-related disciplines and applications. The recently developed bottom-up on-surface synthesis strategy provides us with opportunities for the fabrication of various nanostructures in a flexible and facile manner, which could be investigated by high-resolution microscopic techniques in real space. Herein, we designed and synthesized molecular precursors functionalized with benzal  gem-dibromomethyl groups. A combination of scanning tunneling microscopy, noncontact atomic force microscopy, high-resolution synchrotron radiation photoemission spectroscopy, and density functional theory calculations demonstrated that it is feasible to achieve the direct formation of C-C double-bonded structural motifs via on-surface dehalogenative homocoupling reactions on the Au(111) surface. Correspondingly, we convert the sp3-hybridized state to an sp2-hybridized state of carbon atoms, i. e., from an alkyl group to an alkenyl one. Moreover, by such a bottom-up strategy, we have successfully fabricated poly(phenylenevinylene) chains on the surface, which is anticipated to inspire further studies toward understanding the nature of conductive polymers at the atomic scale.