The roles of membrane permeability and efflux pumps in the toxicity of bisphenol S analogues (2,4-bisphenol S and bis-(3-allyl-4-hydroxyphenyl) sulfone) to Escherichia coli K12

The environmental occurrence, human exposure, and toxicity of novel bisphenol S derivatives: A review

Novel bisphenol S (BPS) derivatives are being increasingly utilized as substitutes to bisphenol A (BPA) and BPS in thermal receipts and other industrial or commercial products. In recent years, the environmental occurrence, human exposure, and toxicity of non-chlorinated and chlorinated BPS derivatives have been investigated in numerous studies. This review summarizes the state-of-art and new knowledge on these aspects and provides recommendations for future research directions. The environmental analysis showed that BPS derivatives have been widely detected in paper products, water, indoor dust, sediment, and municipal sewage sludge. Recent studies have also reported the presence of non-chlorinated BPS derivatives, such as benzenesulfonylbenzene (DDS) and 4-(4-propan-2-yloxyphenyl)sulfonylphenol (BPSIP), in human breast milk, urine, and the maternal-fetal-placental unit. Toxicological studies suggest that BPS derivatives may cause a series of toxic effects, including endocrine-disrupting effects, cytotoxicity, hepatotoxicity, developmental toxicity, and neurotoxicity, some of which have been shown to exhibit adverse effects similar to or even greater than those of BPS. Future studies should focus on elucidating environmental occurrences, half-lives, sources for human exposure, and potential transformation pathways of BPS derivatives, as well as their toxic effects and underlying mechanisms.

2,4-Bisphenol S triggers physiological changes, oxidative stress and lipidome alterations in Gram-positive Enterococcus faecalis at environmental concentrations

2,4-bisphenol S (2,4-BPS) was an emerging BPS analogue as color developers, widely found in the environment. Fish toxicities, cytotoxicity and antiestrogenic effects of 2,4-BPS have been documented at mg L-1, while the toxicity of 2,4-BPS at environmental concentrations (from ng L-1 to μg L-1) were scarce. Bacteria are identified as important components of the ecosystem, while little is known regarding the ecotoxicity of 2,4-BPS on bacteria. Enterococcus faecalis, a good indicator of faecal contamination and anthropogenic pollution, was exposed to 0.5-50 nmol L-1 2,4-BPS. 2,4-BPS resulted in significantly decreased growth but notably increased membrane permeability in E. faecalis compared with the control. Hormetic effects on the expression of genes involved in DNA replication and efflux were observed. Inhibition of biofilm formation and induction of oxidative stress were caused by 0.5, 5 and 50 nmol L-1 2,4-BPS. Fatty acyls, glycerolipids and glycerophospholipids were differentially regulated by 2,4-BPS. Glycerolipid metabolism and glycine, serine and threonine metabolism were significantly altered by 0.5 nmol L-1 2,4-BPS, compared with glycerophospholipid metabolism disturbed by 5 and 50 nmol L-1 2,4-BPS, showing concentration-dependent responses. Trend analysis of differential lipids demonstrated that there were three significant clusters, all of which were enriched in glycerophospholipid metabolism. 2,4-BPS elicited the strongest lipidomic responses at 5 nmol L-1. Our study provides evidence for 2,4-BPS-induced toxicity to E. faecalis at environmental concentrations and contributes to a comprehensive understanding of the interaction between 2,4-BPS and Gram-positive bacteria.

A new understanding of the regulatory mechanism by which Fe/Mn nanoparticles boost Bisphenol A removal using Comamonas testosteroni

Green synthesized iron/manganese nanoparticles (Fe/Mn NPs), acted as an exogenous promoter to enhance the lignin-degrading bacteria Comamonas testosteroni FJ17 resulting in more efficient removal of bisphenol A (BPA). Batch experiments demonstrated that removal efficiency of BPA via cells at a BPA concentration of 10 mg·L-1 increased by 20.9 % when exposed to 100 mg·L-1 Fe/Mn NPs after 48 h (93.63 %) relative to an unexposed control group (72.70 %). TEM and 3D-EEM analysis confirmed that the cell membrane thickness increased from 47 to 80 nm under Fe/Mn NPs exposure, and the TB-EPS secretion was promoted. Meanwhile, Fe/Mn NPs facilitated greater electron transfer capacity of c-cytochrome (0.55 V reduction peak) and an unknown cytochrome substance (0.7 V oxidation peak) on the surface of cells. Studies of the effect of Fe/Mn NPs on both the growth and activity of laccase cells showed that both biomass and laccase secretion increased significantly during the logarithmic growth period (6-36 h). LC-MS analysis and toxicity assessment indicated that Fe/Mn NPs decreased the degradation time of BPA and efficiently reduced the toxicity of its by-products. Transcriptomic analysis revealed 315 up-regulation of the key genes associated with energy supply, membrane translocation, and metabolic pathways upon exposure to Fe/Mn NPs. Such as MFS transporter (2.27-fold), diguanylate cyclase (1.76-fold) and protocatechuate-3,4-dioxygenase (1.62-fold). Overall, Fe/Mn NPs accelerated proliferation by enhancing metabolic capacity and nutrient transport processes, which serves to improve the efficiency of BPA removal.

The role of sheet-like TiO2 in polyamide reverse osmosis membrane for enhanced removal of endocrine disrupting chemicals

Thin film composite (TFC) reverse osmosis (RO) membrane shows good promise for treating wastewater containing endocrine disrupting chemical (EDC) pollutants. The incorporation of functional materials with exceptional structural and physico-chemical properties offers opportunities for the membranes preparation with enhanced permselectivity and better antifouling properties. The present study aims to improve the EDC removal efficiency of TFC RO membrane using two-dimensional titania nanosheets (TNS). RO membrane was prepared by incorporating TNS in the dense layer of polyamide (PA) layer to form thin film nanocomposite (TFN) membrane. The TNS loading was varied and the influences on membrane morphology, surface hydrophilicity, surface charge, as well as water permeability and rejection of EDC were investigated. The results revealed that the inclusion of TNS in the membrane resulted in the increase of water permeability and EDC rejection. When treating the mixture of bisphenol A (BPA) and caffeine at 100 ppm feed concentration, the TFN membrane incorporated with 0.05% TNS achieved water permeability of 1.45 L/m2·h·bar, which was 38.6% higher than that of unmodified TFC membrane, while maintaining satisfactory rejection of >97%. The enhancement of water permeability for TFN membrane can be attributed to their hydrophilic surface and unique nanochannel structure created by the nanoscale interlayer spacing via staking of TiO2 nanosheets. Furthermore, the 0.05TFN membrane exhibited excellent fouling resistance towards BPA and caffeine pollutants with almost 100% flux recovery for three cycles of operations.

Analysis of Regulatory Mechanism of AcrB and CpxR on Colistin Susceptibility Based on Transcriptome and Metabolome of Salmonella Typhimurium

With the increasing and inappropriate use of colistin, the emerging colistin-resistant isolates have been frequently reported during the last few decades. Therefore, new potential targets and adjuvants to reverse colistin resistance are urgently needed. Our previous study has confirmed a marked increase of colistin susceptibility (16-fold compared to the wild-type Salmonella strain) of cpxR overexpression strain JSΔacrBΔcpxR::kan/pcpxR (simplified as JSΔΔ/pR). To searching for potential new drug targets, the transcriptome and metabolome analysis were carried out in this study. We found that the more susceptible strain JSΔΔ/pR displayed striking perturbations at both the transcriptomics and metabolomics levels. The virulence-related genes and colistin resistance-related genes (CRRGs) were significantly downregulated in JSΔΔ/pR. There were significant accumulation of citrate, α-ketoglutaric acid, and agmatine sulfate in JSΔΔ/pR, and exogenous supplement of them could synergistically enhance the bactericidal effect of colistin, indicating that these metabolites may serve as potential adjuvants for colistin therapy. Additionally, we also demonstrated that AcrB and CpxR could target the ATP and reactive oxygen species (ROS) generation, but not proton motive force (PMF) production pathway to potentiate antibacterial activity of colistin. Collectively, these findings have revealed several previously unknown mechanisms contributing to increased colistin susceptibility and identified potential targets and adjuvants for potentiating colistin treatment of Salmonella infections. IMPORTANCE Emergence of multidrug-resistant (MDR) Gram-negative (G-) bacteria have led to the reconsideration of colistin as the last-resort therapeutic option for health care-associated infections. Finding new drug targets and strategies against the spread of MDR G- bacteria are global challenges for the life sciences community and public health. In this paper, we demonstrated the more susceptibility strain JSΔΔ/pR displayed striking perturbations at both the transcriptomics and metabolomics levels and revealed several previously unknown regulatory mechanisms of AcrB and CpxR on the colistin susceptibility. Importantly, we found that exogenous supplement of citrate, α-ketoglutaric acid, and agmatine sulfate could synergistically enhance the bactericidal effect of colistin, indicating that these metabolites may serve as potential adjuvants for colistin therapy. These results provide a theoretical basis for finding potential new drug targets and adjuvants.