Surfactant-enhanced remediation (SER) is one of the most effective methods for petroleum hydrocarbon-contaminated sites compared to single physical and chemical methods. However, biosurfactants are not as commonly used as chemical surfactants, and the actual remediation effects and related mechanisms remain undefined. Therefore, to comprehensively compare the remediation effects and biological mechanisms of biosurfactants and chemical surfactants, soil column leaching experiments including two biosurfactants (rhamnolipids and lipopeptide) and three commercially used chemical surfactants (Tween 80, Triton X-100, and Berol 226SA) were conducted. After seven days of leaching, rhamnolipids exhibited the highest petroleum hydrocarbon removal rate of 61.01%, which was superior to that of chemical surfactants (11.73–18.75%) in n-alkanes C10–C30. Meanwhile, rhamnolipids exhibited a great degradation advantage of n-alkanes C13–C28, which was 1.22–30.55 times that of chemical surfactants. Compared to chemical surfactants, biosurfactants significantly upregulated the soil's biological functions, including soil conductivity (80.90–155.56%), and soil enzyme activities of lipase (90.31–497.10%), dehydrogenase (325.00–655.56%), core enzyme activities of petroleum hydrocarbon degradation, and quorum sensing between species. Biosurfactants significantly changed the composition of Pseudomonas, Citrobacter, Acidobacteriota, and Enterobacter at the genus level. Meanwhile, chemical surfactants had less influence on the bacterial community and interactions between species. Moreover, the biosurfactants enhanced the microbial interactions and centrality of petroleum hydrocarbon degraders in the community based on the network. Overall, this work provides a systematic comparison and understanding of the chemical- and bio-surfactants used in bioremediation. In the future, we intend to apply biosurfactants to practical petroleum hydrocarbon-contaminated fields to observe realistic remediation effects and compare their functional mechanisms.

Plant-derived saponins are bioactive surfactant compounds that can solubilize organic pollutants in environmental matrices, thereby facilitating pollutant remediation. Externally applied saponin has potential to enhance total petroleum hydrocarbon (TPH) biodegradation in the root zone (rhizosphere) of wild plants, but the associated mechanisms are not well understood. For the first time, this study evaluated a triterpenoid saponin (from red ash leaves, Alphitonia excelsa) in comparison to a synthetic surfactant (Triton X-100) for their effects on plant growth and biodegradation of TPH in the rhizosphere of two native wild species (a grass, Chloris truncata, and a shrub, Hakea prostrata). The addition of Triton X-100 at the highest level (1000 mg/kg) in the polluted soil significantly hindered the plant growth (reduced plant biomass and photosynthesis) and associated rhizosphere microbial activity in both the studied plants. Therefore, TPH removal in the rhizosphere of both plant species treated with the synthetic surfactant was not enhanced (at the lower level, 500 mg/kg soil) and even slightly decreased (at the highest level) compared to that in the surfactant-free (control) treatment. By contrast, TPH removal was significantly increased with saponin application (up to 60% in C. truncata at 1000 mg/kg due to enhanced plant growth and associated rhizosphere microbial activity). No significant difference was observed between the two saponin application levels. Dehydrogenase activity positively correlated with TPH removal (p < 0.001) and thus this parameter could be used as an indicator to predict the rhizoremediation efficiency. This work indicates that saponin-amended rhizoremediation could be an environmentally friendly and effective biological approach to remediate TPH-polluted soils. It was clear that the enhanced plant growth and rhizosphere microbial activity played a crucial role in TPH rhizoremediation efficiency. The saponin-induced molecular processes that promoted plant growth and soil microbial activity in the rhizosphere warrant further studies.

Electric and magnetic fields characterized by high efficiency, low consumption and environment-friendly performance have recently generated interest as a possible measure to enhance the performance of the biological treatment process used to remove refractory organics. Few studies have been carried out to-date regarding the simultaneous application of electric and magnetic fields on biofilm process to degrade diclofenac. In this study, 3DEM-BAF was designed to evaluate the electrio-magnetic superposition effect on diclofenac removal performance, kinetics, community structure and synergistic mechanism. The results show that 3DEM-BAF could significantly increase the average removal rate of diclofenac by 65.30 %, 57.46 %, 9.48 % as compared with that of BAF, 3DM-BAF, 3DE-BAF, respectively. The diclofenac degradation kinetic constants and dehydrogenase activity of 3DEM-BAF were almost 6.72 and 2.53 times higher than those of BAF. Microorganisms of 3DEM-BAF in the Methylophilus and Methyloversatilis genera were distinctively enriched, which was attributed to the screening function of electric field and propagation effect of magnetic field. Moreover, three processes were found to contribute to diclofenac degradation, namely electro-magnetic-adsorption, electro-chemical oxidation and electro-magnetic-biodegradation. Thus, the simultaneous application of electric and magnetic fields on biofilm process was demonstrated to be a promising technique as well as a viable alternative in diclofenac degradation enhancement.

The use of reclaimed water in agriculture represents a promising alternative to relieve pressure on freshwater supplies, especially in arid or semiarid regions facing water scarcity. However, this implies introducing micropollutants such as pharmaceutical residues into the environment. The fate and the ecotoxicological impact of valsartan, an antihypertensive drug frequently detected in wastewater effluents, were evaluated in soil-earthworm microcosms. Valsartan dissipation in the soil was concomitant with valsartan acid formation. Although both valsartan and valsartan acid accumulated in earthworms, no effect was observed on biomarkers of exposure (acetylcholinesterase, glutathione S-transferase and carboxylesterase activities). The geometric mean index of soil enzyme activity increased in the soils containing earthworms, regardless of the presence of valsartan. Therefore, earthworms increased soil carboxylesterase, dehydrogenase, alkaline phosphatase, β-glucosidase, urease and protease activities. Although bacterial richness significantly decreased following valsartan exposure, this trend was enhanced in the presence of earthworms with a significant impact on both alpha and beta microbial diversity. The operational taxonomic units involved in these changes were related to four (Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes) of the eight most abundant phyla. Their relative abundances significantly increased in the valsartan-treated soils containing earthworms, suggesting the presence of potential valsartan degraders. The ecotoxicological effect of valsartan on microbes was strongly altered in the earthworm-added soils, hence the importance of considering synergistic effects of different soil organisms in the environmental risk assessment of pharmaceutical active compounds.

Arsenic exposure contributed to the development of human diseases. Arsenic exerted multiple organ toxicities mainly by triggering oxidative stress. However, the signaling pathway underlying oxidative stress is unclear. We previously found that the expression of SFPQ, a splicing factor, was positively associated with urinary arsenic concentration in an arsenic-exposed population, suggesting an oxidative stress regulatory role for SFPQ. To test this hypothesis, we established cell models of oxidative stress in human hepatocyte cells (L02) treated with NaAsO₂. Reactive oxygen species (ROS) synthesis displayed a time- and dose-dependent increase with NaAsO₂ treatment. SFPQ suppression resulted in a 36%–53% decrease in ROS generation, leading to enhanced cellular damage determined by 8-OHdG, comet tail moment, and micronucleus analysis. Particularly, SFPQ deficiency attenuated expression of the oxidase genes DUOX1, DUOX2, NCF2, and NOX2. A fluorescent-based RNA electrophoretic mobility shift assay (FREMSA) and dual-luciferase reporter system revealed that miR-92b-5p targeted DUOX2 mRNA degradation. An RNA immunoprecipitation assay showed an interaction between SFPQ and miR-92b-5p of the miRNA-induced silencing complex (miRISC). Notably, NaAsO₂ treatment diminished the interaction between SFPQ and miR92b-5p, accompanied by decreased binding between miR-92b-5p and 3′-UTR of DUOX2. However, SFPQ deficiency suppressed the dissociation of miR-92b-5p from 3′-UTR of DUOX2, indicating that miR-92b-5p regulated the SFPQ-dependent DUOX2 expression. Taken together, we reveal that SFPQ responds to arsenic-induced oxidative stress by interacting with the miRISC. These findings offer new insight into the potential role of SFPQ in regulating cellular stress response.

Dibutyl phthalate (DBP) is widely used as plasticizer and has been detected in the environment, posing a threat to animal health. However, the effects of DBP on agricultural microbiomes are not known. In this study, DBP levels in black soil were evaluated, and the impact of DBP contamination on the uptake and metabolism of sugars in microbes was assessed by glucose absorption tests, metaproteomics, metabolomics, enzyme activity assays and computational simulation analysis. The results indicated that DBP contamination accelerated glucose consumption and upregulated the expression of porins and periplasmic monosaccharide ATP-binding cassette (ABC) transporter solute-binding proteins (SBPs). DBP and its metabolic intermediates (carboxymuconate and butanol) may form a stable complex with sugar transporters and enhance the rigidity and stability of these proteins. Sugar metabolism resulting in the generation of ATP and reducing agent (NADPH), as well as the expression of some key enzymes (dehydrogenases) were also upregulated by DBP treatment. Moreover, a diverse bacterial community appears to utilize sugar, suggesting that there are widespread effects of DBP contamination on soil microbial ecosystems. The results of this study provide a theoretical basis for investigating the toxicological effects of DBP on microbes in black soil.

Molluscs are sensitive species to the toxic effects of organotin compounds, particularly to masculinisation. Both tributyltin (TBT) and triphenyltin (TPT) have been recently shown to bind to mollusc retinoid X receptor (RXR). If RXR is involved in lipid homeostasis, exposure to TPT would have an immediate effect on endogenous lipids. To test this hypothesis, the ramshorn snail Marisa cornuarietis was exposed to environmentally relevant concentrations of TPT (30, 125, 500 ng/L as Sn) in a semi-static water regime for 7 days. Percentage of lipids and total fatty acid content decreased significantly in TPT-exposed females while the activity of peroxisomal acyl-CoA oxidase, involved in fatty acid catabolism, increased. In addition, fatty acid profiles (carbon chain length and unsaturation degree) were significantly altered in exposed females but not in males. This work highlights the ability of TPT to disrupt lipid metabolism in M. cornuarietis at environmentally realistic concentrations and the higher susceptibility of females in comparison to males. Short-term exposure to the fungicide TPT disrupts lipid metabolism in M. cornuarietis at environmentally realistic concentrations.

The decay of algal biomass and aquatic plants in freshwater lakes leads to the overproduction of autochthonous organic matter (OM) and the exhaustion of dissolved oxygen, impacting the microbial community and subsequent biodegradation of emerging contaminants in sediment. This study explored how the microbial processing of aquatic plant- and algal-derived OM (POM and AOM) mediates 17α-ethinylestradiol (EE2) biodegradation in the anoxic sediments of Lake Taihu in China. In four months of microcosm incubations, the increased concentrations of protein-like substances in AOM and POM exhibited temporary activation on microbial metabolic enzyme activity (fluorescein diacetate hydrolase and dehydrogenase) and significantly promoted the carbon mineralization with iron reduction (P < 0.001). These in turn increased the EE2 biodegradation efficiency to 77–90 ng g⁻¹ in the anoxic sediment. However, a higher EE2 biodegradation of 109 ng g⁻¹ was achieved with the humic acid augmentation containing more quinone-like compounds, showing a weaker substrate-priming effect but accelerated redox cycling of iron and organic substrates in the later period of incubation. The microbial analysis further revealed that the quinone-like compounds in OM were more closely associated with microbial electron transfer and strengthened their interspecies syntrophic cooperation favorable to contaminant biodegradation, even though the connective members exposed to protein-like components upregulated more functional genes related to organic carbon and xenobiotics metabolism and biodegradation. Our findings will help predict the fate of estrogens in various sedimentary environments under increasing eutrophication and further climate change scenarios.

A new bacterium, Rhodococcus sp. S2-17, which could completely degrade an emerging organic pollutant, benzophenone-3 (BP-3), was isolated from contaminated sediment through an enrichment procedure, and its BP-3 catabolic pathway and genes were identified through metabolic intermediate and transcriptomic analyses and biochemical and genetic studies. Metabolic intermediate analysis suggested that strain S2-17 may degrade BP-3 using a catabolic pathway progressing via the intermediates BP-1, 2,4,5-trihydroxy-benzophenone, 3-hydroxy-4-benzoyl-2,4-hexadienedioic acid, 4-benzoyl-3-oxoadipic acid, 3-oxoadipic acid, and benzoic acid. A putative BP-3 catabolic gene cluster including cytochrome P450, flavin-dependent oxidoreductase, hydroxyquinol 1,2-dioxygenase, maleylacetate reductase, and α/β hydrolase genes was identified through genomic and transcriptomic analyses. Genes encoding the cytochrome P450 complex that demethylates BP-3 to BP-1 were functionally verified through protein expression, and the functions of the other genes were also verified through knockout mutant construction and intermediate analysis. This study suggested that strain S2-17 might have acquired the ability to catabolize BP-3 by recruiting the cytochrome P450 complex and α/β hydrolase, which hydrolyzes 4-benzoyl-3-oxoadipic acid to benzoic acid and 3-oxoadipic acid, genes, providing insights into the recruitment of genes of for the catabolism of emerging organic pollutants.

Nowadays, microplastics represent emergent pollutants in terrestrial ecosystems that exert impacts on soil properties, affecting key soil ecological functions. In agroecosystems, plastic mulching is one of the main sources of plastic residues in soils. The present research aimed to evaluate the effects of two types of plastic sheets (un-biodegradable and biodegradable) on soil abiotic (pH, water content, concentrations of organic and total carbon, and total nitrogen) and biotic (respiration, and activities of hydrolase, dehydrogenase, β-glucosidase and urease) properties, and on phytotoxicity (germination index of Sorghum saccharatum L. and Lepidium sativum L.). Results revealed that soil properties were mostly affected by exposure time to plastics rather than the kind (un-biodegradable and biodegradable) of plastics. After six months since mesocosm setting up, the presence of un-biodegradable plastic sheets significantly decreased soil pH, respiration and dehydrogenase activity and increased total and organic carbon concentrations, and toxicity highlighted by S. saccharatum L. Instead, the presence of biodegradable plastic sheets significantly decreased dehydrogenase activity and increased organic carbon concentrations. An overall temporal improvement of the investigated properties in soils covered by biodegradable plastic sheets occurred.