Mapping Blood Lead Levels in China during 1980-2040 with Machine Learning.

Lead poisoning is globally concerning, yet limited testing hinders effective interventions in most countries. We aimed to create annual maps of county-specific blood lead levels in China from 1980 to 2040 using a machine learning model. Blood lead data from China were sourced from 1180 surveys published between 1980 and 2022. Additionally, regional statistical figures for 15 natural and socioeconomic variables were obtained or estimated as predictors. A machine learning model, using the random forest algorithm and 2973 generated samples, was created to predict county-specific blood lead levels in China from 1980 to 2040. Geometric mean blood lead levels in children (i.e., age 14 and under) decreased significantly from 104.4 µg/L in 1993 to an anticipated 40.3 µg/L by 2040. The number exceeding 100 µg/L declined dramatically, yet South Central China remains a hotspot. Lead exposure is similar among different groups, but overall adults and adolescents (i.e., age over 14), females, and rural residents exhibit slightly lower exposure compared to that of children, males, and urban residents, respectively. Our predictions indicated that despite the general reduction, one-fourth of Chinese counties rebounded during 2015-2020. This slower decline might be due to emerging lead sources like smelting and coal combustion; however, the primary factor driving the decline should be the reduction of a persistent source, legacy gasoline-derived lead. Our approach innovatively maps lead exposure without comprehensive surveys.

Effects of the lncRNA MALAT1 gene region rs664589 site mutation on acute myocardial infarction in Chinese Han.

We aimed to study the association between the non-coding region of the lncRNA MALAT1 gene, the non-coding region rs664589 C>G variant, and the risk of acute myocardial infarction (AMI) in the Chinese Han population. 165 NSTEMI and 135 STEMI patients were enrolled in the study. An additional 150 healthy individuals were enrolled as the controls. All subjects were analyzed for the MALAT1 rs664589 locus genotype. The receiver operating curve (ROC) was used to determine the effect of MALAT1 rs664589 single nucleotide polymorphism (SNP) on the diagnosis of AMI by plasma lncRNA MALAT1. The MALAT1 rs664589 site G allele carrier was 1.39 times more likely to have NSTEMI than the C allele carrier (95% CI: 1.16-1.61, P = 0.001) and 1.59 times more likely to have STEMI than the C allele carrier (95% CI: 1.31-1.85, P < 0.001). The MALAT1 rs664589 site C>G mutation resulted in an increase in the area under the ROC curve (AUC) of the plasma lncRNA MALAT1 level for the diagnosis of AMI. The plasma lncRNA MALAT1 levels in AMI patients were negatively correlated with hsa-miR-1972, hsa-miR-194-5p, hsa-miR-4717-5p, hsa-miR-6735-3p, and hsa-miR-3677-5p (r = -0.81, -0.75, -0.66, -0.71, and -0.88). The C>G mutation of MAL6641 rs664589 causes an increased risk of AMI in the Chinese Han population. The SNP at this site affects the value of plasma lncRNA MALAT1 in the diagnosis of AMI. The specific mechanism may indicate that the C>G mutation of the MALAT1 rs664589 changes the regulation of miRNAs expression by lncRNA MALAT1.

Enhanced biodegradation of polychlorinated biphenyls by co-cultivation of resuscitated strains with unique advantages.

The investigation into viable but non-culturable (VBNC) bacteria through the implementation of resuscitation promoting factors (Rpfs) has broadened the potential sources for isolating strains capable of degrading polychlorinated biphenyls (PCBs). Nonetheless, there has been limited research on the efficacy of resuscitated strains and the potential improvement of their performance through co-cultivation. In this work, the PCB degradation potential of resuscitated strains, specifically Pseudomonas sp. HR1 and Achromobacter sp. HR2, as well as their co-cultures, was investigated. Of particular importance was the comparative analysis between the optimal co-culture and individual strains regarding their ability to degrade PCB homologs and mineralize intermediate metabolites. The results suggested that the resuscitated strains HR1 and HR2 demonstrated robust growth and effective degradation of Aroclor 1242. The co-culture CO13, with an optimal HR1 to HR2 ratio of 1:3, exhibited a remarkable improvement in PCB degradation and intermediate metabolite mineralization compared to individual strains. Analysis of functional genes and degradation metabolites revealed that both the individual strains and co-culture CO13 degraded PCBs via the HOPDA-benzoate pathway, then mineralized through protocatechuate meta- and ortho-cleavage pathways, as well as the catechol ortho-cleavage pathway. This study represents the first documentation of the improved PCB degradation through the co-cultivation of resuscitated strains, which highlights the great promise of these resuscitated strains and their co-cultures as effective bio-inoculants for enhanced bioremediation.

Analysis of the Predictive Efficacy of Serum suPAR Combined with APN and IgE Test and the Relationship of Patients with CHF and Cardiac Function.

Background: Chronic heart failure (CHF) is a complex cardiovascular disorder resulting from prolonged heart disease, leading to structural and functional damage, weakened myocardial contraction, and inadequate cardiac output for daily metabolism. The purpose of study is accurate evaluation and early identification of cardiac function and ventricular remodeling through effective biochemical indicators. Methods: This study, conducted from April 2020 to March 2021, included 100 CHF patients meeting the Chinese Guidelines for the Diagnosis and Treatment of Heart Failure 2020 from First People's Hospital of Linping District, ascertaining a confirmed diagnosis based on these established guidelines. The objective of detecting these biomarkers is not for early diagnosis, given that the subjects are already diagnosed according to the guidelines. Instead, our focus is on using these biomarkers to assess disease severity, prognosis, or treatment response in the context of diagnosed CHF patients. Classification comprised 42 ischemic and 58 non-ischemic CHF cases, with NYHA cardiac function grading (I, II, III-IV) and left ventricular ejection fraction (LVEF) categorization (≤ 40%, >40%). A control group of 100 healthy volunteers was selected for comparison. SuPAR, APN, and IgE expressions were analyzed among different groups and LVEF categories. Diagnostic efficacy was assessed through ROC curves, and correlations with cardiac function and LVEF were explored. Results: SuPAR, APN, and IgE expressions were significantly higher in CHF patients compared to the control group. Increasing cardiac function grades in CHF patients correlated with a gradual elevation in suPAR, APN, and IgE expressions. Comparing LVEF groups, CHF patients with LVEF ≤ 40% exhibited significantly higher suPAR, APN, and IgE expressions. Combined detection of suPAR, APN, and IgE demonstrated superior diagnostic accuracy (AUC of 0.899) compared to individual markers. Positive correlations were observed between suPAR, APN, IgE, and cardiac function grades, while LVEF showed a significant negative correlation with these biomarkers. Conclusions: SuPAR, APN, and IgE expressions are elevated in CHF patients, and their combined detection serves as a highly efficient auxiliary diagnostic method. The findings offer valuable insights into the diagnosis and treatment of CHF patients.

Unveiling the distribution characteristics of rpf-like genes and indigenous resuscitation promoting factor production in PCB-contaminated soils.

Resuscitation promoting factors (Rpfs), known for their anti-dormancy cytokine properties, have been extensively investigated in the medical field. Although the Rpf from Micrococcus luteus has been successfully utilized to resuscitate and stimulate microbial populations for the degradation of polychlorinated biphenyls (PCBs), the presence of indigenous Rpf homologs in PCB-contaminated soils has not been established. In this study, the distribution characteristics of rpf-like genes and indigenous strain capable of producing Rpf in PCB-contaminated soils were explored. The results revealed the widespread presence of Rpf-like domains and their associated genes, particularly in close association with heavy metals and PCBs. The rpf-like genes were predominantly found in Proteobacteria and displayed a positive correlation with genes involved in PCB degradation and viable but non-culturable (VBNC) formation. Notably, the recombinant Rpf-Ac protein derived from the indigenous strain Achromobacter sp. HR2 exhibited muralytic activity and demonstrated significant efficacy in resuscitating the growth of VBNC cells, while also stimulating the growth of normal cells. These findings shed light on the prevalent presence of Rpf homologs in PCB-contaminated soils and their potential to resuscitate functional populations in the VBNC state, thereby enhancing in situ bioremediation.

Resuscitation-Promoting Factor Accelerates Enrichment of Highly Active Tetrachloroethene/Polychlorinated Biphenyl-Dechlorinating Cultures.

The anaerobic bioremediation of polychlorinated biphenyls (PCBs) is largely impeded by difficulties in massively enriching PCB dechlorinators in short periods of time. Tetrachloroethene (PCE) is often utilized as an alternative electron acceptor to preenrich PCB-dechlorinating bacteria. In this study, resuscitation promoting factor (Rpf) was used as an additive to enhance the enrichment of the microbial communities involved in PCE/PCBs dechlorination. The results indicated that Rpf accelerates PCE dechlorination 3.8 to 5.4 times faster than control cultures. In Aroclor 1260-fed cultures, the amendment of Rpf enables significantly more rapid and extensive dechlorination of PCBs. The residual high-chlorinated PCB congeners (≥5 Cl atoms) accounted for 36.7% and 59.8% in the Rpf-amended cultures and in the corresponding controls, respectively. This improvement was mainly attributed to the enhanced activity of the removal of meta-chlorines (47.7 mol % versus 14.7 mol %), which did not appear to affect dechlorination pathways. The dechlorinators, including Dehalococcoides in Chloroflexi and Desulfitobacterium in Firmicutes, were greatly enriched via Rpf amendment. The abundance of nondechlorinating populations, including Methanosarcina, Desulfovibrio, and Bacteroides, was also greatly enhanced via Rpf amendment. These results suggest that Rpf serves as an effective additive for the rapid enrichment of active dechlorinating cultures so as to provide a new approach by which to massively cultivate bioinoculants for accelerated in situ anaerobic bioremediation. IMPORTANCE The resuscitation promoting factor (Rpf) of Micrococcus luteus has been reported to resuscitate and stimulate the growth of functional microorganisms that are involved in the aerobic degradation of polychlorinated biphenyls (PCBs). However, few studies have been conducted to investigate the role of Rpf on anaerobic microbial populations. In this study, the enhancement of Rpf on the anaerobic microbial dechlorination of PCE/PCBs was discovered. Additionally, the Rpf-responsive populations underlying the enhanced dechlorination were uncovered. This report reveals the rapid enrichment of active dechlorinating cultures via Rpf amendment, and this sheds light on massively enriching PCB dechlorinators in short periods of time. The enhanced in situ anaerobic bioremediation of PCBs could be expected by supplementing Rpf.

Neglected Drivers of Antibiotic Resistance: Survival of Extended-Spectrum ß-Lactamase-Producing Pathogenic Escherichia coli from Livestock Waste through Dormancy and Release of Transformable Extracellular Antibiotic Resistance Genes under Heat Treatment.

Extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae has caused a global pandemic with high prevalence in livestock and poultry, which could disseminate into the environment and humans. To curb this risk, heat-based harmless treatment of livestock waste was carried out. However, some risks of the bacterial persistence have not been thoroughly assessed. This study demonstrated that antibiotic-resistant bacteria (ARB) could survive at 55 °C through dormancy, and simultaneously transformable extracellular antibiotic resistance genes (eARGs) would be released. The ESBL-producing pathogenic Escherichia coli CM1 from chicken manure could enter a dormant state at 55 °C and reactivate at 37 °C. Dormant CM1 had stronger ß-lactam resistance, which was associated with high expression of ß-lactamase genes and low expression of outer membrane porin genes. Resuscitated CM1 maintained its virulence expression and multidrug resistance and even had stronger cephalosporin resistance, which might be due to the ultra-low expression of the porin genes. Besides, heat at 55 °C promoted the release of eARGs, some of which possessed a certain nuclease stability and heat persistence, and even maintained their transformability to an Acinetobacter baylyi strain. Therefore, dormant multidrug-resistant pathogens from livestock waste will still pose a direct health risk to humans, while the resuscitation of dormant ARB and the transformation of released eARGs will jointly promote the proliferation of ARGs and the spread of antibiotic resistance.

Ceramsite made from remediated soil: A risk assessment of its potential role serving as urban street cushion.

To promote the reuse of remediated soil (RS) and facilitate the cleanup of rainwater in sponge city, we investigated the effects of ceramsite made from RS serving as urban street cushion. Ceramsite was prepared by RS or pollution-free soil (PS) and showed no difference in physical properties. Compared with gravel, ceramsite had purification effects on effluents, reducing the content of chemical oxygen demand, total nitrogen, and ammoniacal nitrogen. However, the content of total phosphorus and the concentration of Cr(VI) and arsenic slightly increased in ceramsite groups, inferring potential risk. Microbial community analysis proved that ceramsite promoted microbial growth and increased microbial diversity. A long-term risk assessment indicated that ceramsite was good at fixing heavy metals during leaching process. Taken together, ceramsite prepared from RS could serve as excellent urban street cushion with little potential risk to surroundings.

Phenotype and metabolism alterations in PCB-degrading Rhodococcus biphenylivorans TG9T under acid stress.

Environmental acidification impairs microorganism diversity and their functions on substance transformation. Rhodococcus is a ubiquitously distributed genus for contaminant detoxification in the environment, and it can also adapt a certain range of pH. This work interpreted the acid responses from both phenotype and metabolism in strain Rhodococcus biphenylivorans TG9T (TG9) induced at pH 3. The phenotype alterations were described with the number of culturable and viable cells, intracellular ATP concentrations, cell shape and entocyte, degradation efficiency of polychlorinated biphenyl (PCB) 31 and biphenyl. The number of culturable cells maintained rather stable within the first 10 days, even though the other phenotypes had noticeable alterations, indicating that TG9 possesses certain capacities to survive under acid stress. The metabolism responses were interpreted based on transcription analyses with four treatments including log phase (LP), acid-induced (PER), early recovery after removing acid (RE) and later recovery (REL). With the overview on the expression regulations among the 4 treatments, the RE sample presented more upregulated and less downregulated genes, suggesting that its metabolism was somehow more active after recovering from acid stress. In addition, the response mechanism was interpreted on 10 individual metabolism pathways mainly covering protein modification, antioxidation, antipermeability, H+ consumption, neutralization and extrusion. Furthermore, the transcription variations were verified with RT-qPCR on 8 genes with 24-hr, 48-hr and 72-hr acid treatment. Taken together, TG9 possesses comprehensive metabolism strategies defending against acid stress. Consequently, a model was built to provide an integrate insight to understand the acid resistance/tolerance metabolisms in microorganisms.

Oxidative dehalogenation and mineralization of polychlorinated biphenyls by a resuscitated strain Streptococcus sp. SPC0.

Most functional microorganisms cannot be cultivated due to entering a viable but non-culturable (VBNC) state, which limits the characterization and application of polychlorinated biphenyl (PCB)-degrading strains. Resuscitating VBNC bacteria could provide huge candidates for obtaining high-efficient PCB degraders. However, limited studies have focused on the ability of resuscitated strains for PCBs degradation. In the present study, whole-genome analysis of a resuscitated strain SPC0, and its performances in degradation of three prevalent PCB congeners (PCBs 18, 52 and 77) were investigated. The results indicate that the strain SPC0 belonged to the genus Streptococcus, possessed the degradation potential for aromatic xenobiotics. The SPC0 could effectively degrade PCBs 18 and 52, but exhibited lower degradation efficiency of PCB 77. Degradation of PCBs 18 and 52 could be fitted well by zero-order model, whereas the fittest model for PCB 77 degradation was pseudo second-order kinetics. The bph genes expression, chloride ions release and degradation metabolites identification, suggest that SPC0 possessed the capability of oxidative dehalogenation and mineralization of PCBs. Interestingly, SPC0 can degrade PCBs via the bph-encoded biphenyl pathway, and further mineralize metabolite dichlorobenzoate via protocatechuate pathway. This study is the first to show that a strain belonging to genus Streptococcus possessed PCB-degrading capability, which uncovered the powerful potential of resuscitated strains for bioremediation of PCB-contaminated sites.

Biphenyl-degrading Bacteria Isolation with Laser Induced Visualized Ejection Separation Technology and Traditional Colony Sorting.

In this work, biphenyl was used as carbon source to enrich microorganisms from polychlorinated biphenyls (PCBs)-contaminated paddy soil samples, and the taxonomic structures in both of the soil samples and the fourth-generation enrichments were examined with high-throughput sequencing. Single cells were isolated from the enrichments via single cell sorting technology named Laser Induced Visualized Ejection Separation Technology (LIVEST) and also traditional single colony sorting, and the genera of the isolates were identified using 16S rRNA sequencing. The results from high-throughput sequencing present that enrichment from generation to generation can considerably change the microbial community. Comparing the two sorting methods, the LIVEST is more time-saving and cell-targeted for microbial resource exploration. Based on the further verification of biphenyl degradation, it was found that some strains belonging to genera Macrococcus, Aerococcus and Metabacillus are capable in degrading biphenyl, which have not been reported yet.

The amendment of Organic matters enhances the anaerobic dechlorination of Polychlorinated Biphenyls in Paddy Soil.

The toxicity of high-chlorinated polychlorinated biphenyls (PCBs) can be efficiently reduced through anaerobic dechlorination. However, this approach suffers a lot in face of in situ microbial remediations, like a shortage of biomass. In this study, we showed that the amendment of organic matters could help microbiota in paddy soil with anaerobic dechlorination and greatly shortened the lag period. The presence of organic matters offered a better environment for dechlorinating bacteria. They provided not only a more strictly anaerobic milieu but also copious carbon sources. By using high-throughput 16S rRNA gene sequencing, genera Dehalobacter, Dehalobacterium, and Desulfitobacterium capable of dechlorination were identified in enriched cultures. Taken together, this study proved that extra organic matters can promote anaerobic dechlorination in paddy soil slurry microcosm systems, which provides new insights into the bioremediation of PCB-contaminated soils.

Viable but Nonculturable State of Yeast Candida sp. Strain LN1 Induced by High Phenol Concentrations.

Microbial degradation plays an important role in environmental remediation. However, most microorganisms' pollutant-degrading capabilities are weakened due to their entry into a viable but nonculturable (VBNC) state. Although there is some evidence for the VBNC state of pollutant-degrading bacteria, limited studies have been conducted to investigate the VBNC state of pollutant degraders among fungi. In this work, the morphological, physiological, and molecular changes of phenol-degrading yeast strain LN1 exposed to high phenol concentrations were investigated. The results confirmed that Candida sp. strain LN1, which possessed a highly efficient capability of degrading 1,000 mg/liter of phenol as well as a high potential for aromatic compound degradation, entered into the VBNC state after 14 h of incubation with 6,000 mg/liter phenol. Resuscitation of VBNC cells can restore their phenol degradation performance. Compared to normal cells, significant dwarfing, surface damage, and physiological changes of VBNC cells were observed. Molecular analysis indicated that downregulated genes were related to the oxidative stress response, xenobiotic degradation, and carbohydrate and energy metabolism, whereas upregulated genes were related to RNA polymerase, amino acid metabolism, and DNA replication and repair. This report revealed that a pollutant-degrading yeast strain entered into the VBNC state under high concentrations of contaminants, providing new insights into its survival status and bioremediation potential under stress. IMPORTANCE The viable but nonculturable (VBNC) state is known to affect the culturability and activity of microorganisms. However, limited studies have been conducted to investigate the VBNC state of other pollutant degraders, such as fungi. In this study, the VBNC state of a phenol-degrading yeast strain was discovered. In addition, comprehensive analyses of the morphological, physiological, and molecular changes of VBNC cells were performed. This study provides new insight into the VBNC state of pollutant degraders and how they restored the activities that were inhibited under stressful conditions. Enhanced bioremediation performance of indigenous microorganisms could be expected by preventing and controlling the formation of the VBNC state.

Potential Role of Methanogens in Microbial Reductive Dechlorination of Organic Chlorinated Pollutants In Situ.

Previous studies often attribute microbial reductive dechlorination to organohalide-respiring bacteria (OHRB) or cometabolic dechlorination bacteria (CORB). Even though methanogenesis frequently occurs during dechlorination of organic chlorinated pollutants (OCPs) in situ, the underestimated effect of methanogens and their interactions with dechlorinators remains unknown. We investigated the association between dechlorination and methanogenesis, as well as the performance of methanogens involved in reductive dechlorination, through the use of meta-analysis, incubation experiment, untargeted metabolomic analysis, and thermodynamic modeling approaches. The meta-analysis indicated that methanogenesis is largely synchronously associated with OCP dechlorination, that OHRB are not the sole degradation engineers that maintain OCP bioremediation, and that methanogens are fundamentally needed to sustain microenvironment functional balance. Laboratory results further confirmed that Methanosarcina barkeri (M. barkeri) promotes the dechlorination of γ-hexachlorocyclohexane (γ-HCH). Untargeted metabolomic analysis revealed that the application of γ-HCH upregulated the metabolic functioning of chlorocyclohexane and chlorobenzene degradation in M. barkeri, further confirming that M. barkeri potentially possesses an auxiliary dechlorination function. Finally, quantum analysis based on density functional theory (DFT) indicated that the methanogenic coenzyme F430 significantly reduces the activation barrier to dechlorination. Collectively, this work suggests that methanogens are highly involved in microbial reductive dechlorination at OCP-contaminated sites and may even directly favor OCP degradation.

Biofertilizer-induced response to cadmium accumulation in Oryza sativa L. grains involving exogenous organic matter and soil bacterial community structure.

The accumulation of cadmium (Cd) in Oryza sativa L., the world's most significant staple crop, is a health threat to millions of people. The objective of this study was to evaluate the effectiveness of commercially available biofertilizers (with high (BF2) and low organic matter (OM) content (BF1)) on Cd accumulation in two types of soils and to determine the bacterial community responses by high-throughput sequencing. The study was conducted in the form of pot experiment in greenhouse in 2018. Four treatments were set: BF1, BF2, organic fertilizer (OF), and control (CK) and the amendments were applied before the rice cultivation. The results showed that the addition of biofertilizers immobilized or mobilized Cd in soils, depending on the soil type and the OM content in biofertilizers. The exogenous OM in biofertilizers was the driving factor for the difference in pH and Cd accumulation in rice grains. The application of biofertilizers with high OM content was effective in reducing Cd accumulation in the rice grains (19.7% lower than CK) by significantly increasing soil pH (from 6.02 to 6.67) in acid silt loam soil (TZ). The consumption of acid fermentation products by soil chemoorganotrophs and the complexation of organic anions in the biofertilizer treatment tended to buffer the pH drop in the drainage and decrease the Cd availability. However, in the weak acid silty clay loam soil (SX), the addition of biofertilizer with high OM significantly increased Cd accumulation in rice grains (21.9% higher than CK), probably owing to the release of acid substances, resulting from the significant increase of the predominant bacteria Chloroflexi. The addition of biofertilizer with low OM content did not significantly change Cd accumulation in rice grains or affect the soil microbial structures in both soils. In conclusion, the effects of biofertilizer on rice Cd accumulation were related to the OM content and soil bacterial community. Biofertilizers with high organic matter may not be suitable for amendments in the paddy soils with high clay content to reduce Cd accumulation in rice grains.

Effects of environmental factors on the removal of heavy metals by sulfide-modified nanoscale zerovalent iron.

Sulfide-modified nanoscale zerovalent iron (S-nZVI) has excellent reducing performance for heavy metals in water. The influence of environmental factors on the reactivity can be used to explore the practical feasibility of S-nZVI and analyze the reaction mechanism in depth. This study compared the removal effect and mechanism of Cu2+ and Ni2+ by nanoscale zerovalent iron (nZVI), S-nZVI, and carboxymethyl cellulose-modified nanoscale zerovalent iron (CMC-nZVI). The results show that the pseudo-first-order kinetic constant of Cu2+ removal by nZVI, S-nZVI, and CMC-nZVI was 1.384, 1.919, and 2.890 min-1, respectively, and the rate of Ni2+ removal was 0.304, 0.931, and 0.360 min-1, respectively. The removal mechanism of S-nZVI was similar to that of nZVI and CMC-nZVI. Specifically, Cu2+ was predominantly removed by reduction, while Ni2+ removal included adsorption and reduction. Environmental factors had a specific inhibitory effect on the removal of Cu2+ but had a negligible impact on Ni2+. The condition of low pH, the presence of Cl- and humic acid (HA) promoted the corrosion consumption of Fe0, in which H+ directly corroded Fe0 at low pH. At the same time, Cl- and HA inhibited the adsorption or binding of heavy metal ions on the particle surface, thereby reducing the electron transfer and utilization efficiency. The passivation of NO3- reduced the anaerobic corrosion of the material in water but suppressed the release of electrons, thereby reducing the reduction efficiency of the three types of materials. The anaerobic corrosion of S-nZVI was less affected by environmental factors, and it can still maintain more than 80% of the electronic utilization efficiency under different environmental factors, which illustrates that S-nZVI has broad prospects for practical applications in heavy metal polluted water.

Inactivation of antibiotic-resistant bacteria and antibiotic resistance genes by electrochemical oxidation/electro-Fenton process.

Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the environment are of great concern due to their potential risk to human health. The effluents from wastewater treatment plants and livestock production are major sources of ARB and ARGs. Chlorination, UV irradiation, and ozone disinfection cannot remove ARGs completely. In this study, the potential of electrochemical oxidation and electro-Fenton processes as alternative treatment technologies for inactivation of ARB and ARGs in both intracellular and extracellular forms was evaluated. Results showed that the electrochemical oxidation process was effective for the inactivation of selected ARB but not for the removal of intracellular ARGs or extracellular ARGs. The electro-Fenton process was more effective for the removal of both intracellular and extracellular ARGs. The removal efficiency after 120 min of electro-Fenton treatment under 21.42 mA/cm2 was 3.8 logs for intracellular tetA, 4.1 logs for intracellular ampC, 5.2 logs for extracellular tetA, and 4.8 logs for extracellular ampC, respectively in the presence of 1.0 mmol/L Fe2+. It is suggested that electrochemical oxidation is an effective disinfection method for ARB and the electro-Fenton process is a promising technology for the removal of both intracellular and extracellular ARGs in wastewater.

Alternative Evaluation to Earthworm Toxicity Test in Polychlorinated Biphenyls Spiked and Remediated Soils.

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants that pose a threat to environment and human health. Aiming at predicting PCBs risk in actual soil ecosystem, this study was conducted by chemical and biological methods to assess the bioavailability of PCBs in spiked soil, and in field-contaminated soils before or after remediation. The three chemical methods were Soxhlet, n-butanol and hydroxypropyl-ß-cyclodextrin (HPCD). Results were compared to actual PCB bioaccumulation in earthworms (Eisenia fetida). HPCD extraction was the best to predict the actual PCB bioaccumulation in all soils. The results suggest that HPCD could be an effective alternative method to earthworm toxicity test. This study provides strategy to understand the toxicity assessment in contaminated soil and soil after remediation.

Biodegradation and chemotaxis of polychlorinated biphenyls, biphenyls, and their metabolites by Rhodococcus spp.

Two biphenyl-degrading bacterial strains, SS1 and SS2, were isolated from polychlorinated biphenyl (PCB)-contaminated soil. They were identified as Rhodococcus ruber and Rhodococcus pyridinivorans based on the 16S rRNA gene sequence, as well as morphological, physiological and biochemical characteristics. SS1 and SS2 exhibited tolerance to 2000 and 3000 mg/L of biphenyl. And they could degrade 83.2 and 71.5% of 1300 mg/L biphenyl within 84 h, respectively. In the case of low-chlorinated PCB congeners, benzoate and 3-chlorobenzoate, the degradation activities of SS1 and SS2 were also significant. In addition, these two strains exhibited chemotactic response toward TCA-cycle intermediates, benzoate, biphenyl and 2-chlorobenzoate. This study indicated that, like the flagellated bacteria, non-flagellated Rhodococcus spp. might actively seek substrates through the process of chemotaxis once the substrates are depleted in their surroundings. Together, these data provide supporting evidence that SS1 and SS2 might be good candidates for restoring biphenyl/PCB-polluted environments.

Effects of structurally different noncoplanar and coplanar PCBs on HELF cell proliferation, cell cycle, and potential molecular mechanisms.

Polychlorinated biphenyls (PCBs) are a group of chemicals that persist in the environment, indoors, and humans. Lung exposure to airborne and food contaminants, such as PCBs, may cause possible lung disorders, such as cancer. In the present study, we investigated the effects of structurally different lower chlorinated (≤4Cl), noncoplanar PCB40, and coplanar PCB77 on human lung fibroblast cell line (HELF) cell proliferation, cell cycle progression, and possible molecular mechanisms. Noncoplanar PCB40 and coplanar PCB77 exhibited concentration- and time-dependent biphasic dose-response effects on HELF cell proliferation. Noncoplanar PCB40 and coplanar PCB77 induced 23 and 45% cytotoxicity at higher concentrations than the control. The flow cytometry analysis showed that exposure to PCB40 caused a significant increase in time spent in the G1 phase but decreased length of the S phase in a concentration- and time-dependent manner, whereas PCB77 exposure decreased time spent in the G1 and S phases but increased time spent in the G2 phase. Western blot analysis indicated that PCB77 increased the expression of cyclin E, CDK2, p21, and caspase-9, while PCB40 decreased the expression of these proteins (except CDK2 and p21). An increase in CDK expression after exposure to PCB77 suggests that it may cause carcinogenic effects on HELF cells at higher doses. Our results also demonstrate that the different cytotoxic effects induced by coplanar and nonplanar PCBs were correlated with their structural characteristics; the coplanar congener was more cytotoxic than the nonplanar congener. The study elaborates threshold levels for these chemicals and suggests that the cytotoxicity mechanisms by which PCB congeners act on HELF cells depend on their planarity and chemical structures. Furthermore, the study will be important for developing antidotes to the adverse effects and risk assessment practices for PCBs. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1183-1190, 2017.