Contributions of Abiotic and Biotic Processes to the Aerobic Removal of Phenolic Endocrine-Disrupting Chemicals in a Simulated Estuarine Aquatic Environment

Bioprospecting photosynthetic microorganisms for the removal of endocrine disruptor compounds

Endocrine disruption compounds can be found in various daily products, like pesticides, along with cosmetic and pharmaceutical commodities. Moreover, occurrence of EDCs in the wastewater alarms the urgency for their removal before discharge owing to the harmful effect for the environment and human health. Compared to implementation of physical and chemical strategies, cultivation of photosynthetic microorganisms has been acknowledged for their high efficiency and eco-friendly process in EDCs removal along with accumulation of valuable byproducts. During the process, photosynthetic microorganisms remove EDCs via photodegradation, bio-adsorption, -accumulation, and -degradation. Regarding their high tolerance in extreme environment, photosynthetic microorganisms have high feasibility for implementation in wastewater treatment plant. However, several considerations are critical for their scaling up process. This review discussed the potency of EDCs removal by photosynthetic microorganisms and focused on the efficiency, mechanism, challenge, along with the prospect. Details on the mechanism's pathway, accumulation of valuable byproducts, and recent progress in scaling up and application in real wastewater were also projected in this review.

Key factors influencing pollution of heavy metals and phenolic compounds in mangrove sediments, South China

Concentrations of heavy metals (HMs) and phenolic compounds with factors which potentially affected their spatial distribution were investigated in mangrove sediments, South China. Compared to Qi'ao, Futian sediments exhibited higher levels of Pb and nonylphenol (NP), but lower levels of Co and Ni. Seasonal variation showed higher concentrations of Pb, Cr, Co, NP and bisphenol A (BPA), while lower concentration of methylparaben (MP) in wet than dry season. Contaminant levels in sediments collected at different tidal heights showed insignificant variations, except for Zn and NP. MP was found negatively correlated with nearly all HMs and BPA, whereas the latter exhibited positive correlations with each other. Sedimentary total carbon, total nitrogen, C/N and N/P ratios were screened as the most influential factors affecting the distribution of these contaminants. Additionally, both salinity and total phosphate exhibited positive, while both pH and sedimentary particle size registered negative correlation, with one or more contaminants.

Dark transformation from 17β-estradiol to estrone initiated by hydroxyl radical in dissolved organic matter

The occurrence and fate of 17β-estradiol (E₂) in natural water have gained extensive attention owing to its high ecotoxic risk to wildlife. Dissolved organic matter (DOM) is a ubiquitous water constituent and contributes significantly to E₂ removal, although the reaction mechanism is rarely clarified. The present study aims to investigate E₂ transformation in water containing fresh or aged DOM surrogates at environmentally relevant concentrations in the dark. Experiments along with radical probes of benzene and furfuryl alcohol reveal that reactive radicals, particularly hydroxyl radical (·OH), formed non-photochemically at higher concentrations in aged DOM than in fresh DOM. The contribution of ·OH in E₂ removal is indicated by the decreases in the removal of radical probes in the presence of E₂; moreover, E₂ removal is inhibited in the presence of radical scavengers. The dose-dependent inhibitive effect of substrate concentrations, including E₂ and coexistent propylparaben, shows that the radical concentration is a limiting factor for E₂ removal, which could be enhanced by increasing DOM concentration, dissolved oxygen, and light supply. As the main byproduct, estrone (E₁) is persistent in the current DOM water in the dark, but it can be easily photodegraded when exposed to light. Theoretical analysis reveals that the initial step is ·OH-initiated H- abstraction on the hydroxyl group in the cyclopentane ring of E₂. The formed singlet excited state of E₂ undergoes further intramolecular rearrangement and oxidative dehydrogenation to generate E₁ and the hydroperoxy radical (·HO₂). Considering the universal occurrence of E₂ in DOM-rich aquatic matrices, the present findings have special implications for the biogeochemical cycle and risk assessment of this pollutant in natural aquatic environments, particularly those beyond the photic zone.

Characterization of benthic biofilms in mangrove sediments and their variation in response to nutrients and contaminants

Diatom-dominated biofilms and associated extracellular polymeric substances (EPS) may adapt to the stress of long-term exposure to nutrients and anthropogenic contaminants. However, such interactions in contaminated mangrove sediments have rarely been reported. Based on the in situ characterization of biofilm components and environmental factors, the present study aimed to explore the key factors involved in shaping sediment biofilms through correlational and multivariate analyses. The pennate diatom Navicula is the core taxon that plays a crucial role in balancing the abundance of Nitzschia and Cyclotella, and is the main producer of bound-polysaccharides. The taxa composition shifts in a high N/P matrix, with the populations of pennate diatoms increasing but that of centric diatoms decreasing. High nutrient concentrations yield more number of diatoms and elevated levels of EPS. Bacteria are the main consumers of EPS and tend to be more symbiotic with Nitzschia than the other two diatom taxa. Some bound-polysaccharides dominated by arabinose and glucose units are transformed into the colloidal fraction, whereas other conservative ones serve as structural materials in concert with the bound-proteins. The planktonic phase of Cyclotella breaks down the structural EPS secreted by pennate diatoms in a process that directly affects the dynamic renewal of benthic biofilms. Most heavy metals as well as bisphenol A inhibit the abundance of bacteria and diatoms but enhance most EPS fractions except bound-polysaccharides. The response of structural EPS to specific contaminants varies, exhibiting increases in Co and Ni levels but decreases in nonylphenol and methylparaben levels. The present study improves our understanding of the microbial carbon loop of benthic biofilms in mangrove ecosystems under stress by nutrients and mixed contaminants.

Sexual hormones in a coastal river adjacent to the Bohai Sea: Characteristic pollutants and dominantly influencing factors

Characteristic sexual hormones (SHs) and the factors that dominantly influence their occurrence in coastal ecosystems are less understood. This study verified the relationships between SHs and environmental factors and further inferred the possible controlling mechanisms of SH distribution. A characteristic pollutant of SHs was first proposed by determining the contamination level and ecological risks of SHs (seven species) in a coastal river adjacent to the Bohai Sea. The results showed that the 17β-oestradiol (17β-E2), estriol (E3), and 17α-ethynylestradiol (EE2) had high mean concentrations of 11.20 (±1.31), 10.17 (±4.91), and 16.71 (±0.88) ng L^-1, respectively, in the river water. The concentration of estrone (E1) was positively related to microbial substances of DOMs (p < 0.05). The humification index (HIX) had a negative relationship with E3 (p < 0.05). In water, the distribution of total SHs was regulated by the HIX and fluorescence index (FI), which might be related to photodegradation reactions. The 17α-oestradiol (17α-E2) and EE2 were related to humified organic matter, while E3 and androstenedione (ADD) were influenced by sewage input. The 17β-E2, E1, and 17α-E2 may be derived from animal sources, while E3, ADD, EE2, and progesterone were from human activities. Oestrogens, including E1, 17α-E2, 17β-E2, and EE2, displayed higher ecological risks than androgens and progesterone, with medium to high risk in most sites. The 17β-E2 was regarded as a characteristic pollutant of SHs throughout the river system, which displayed the highest risk. This paper may provide a reference for SH risk management and control.

Migration and abiotic transformation of estrone (E1) and estrone-3-sulfate (E1-3S) during soil column transport

Steroid estrogens have received worldwide attention and given rise to great challenges of aquatic ecosystems security, posing potential adverse effects on aquatic organisms and human health even at low levels (ng/L). The present study focused on understanding the mobility and abiotic transformation of estrone (E1) and estrone-3-sulfate (E1-3S) over spatial and time scales during soil transport. Column transport experiments showed that the migration capacity of E1-3S was far stronger than E1 in soil. The calculated groundwater ubiquity score and leachability index values also indicated the high leaching mobility of E1-3S. The hydrolysis of E1-3S and abiotic transformation into estradiol and estriol was observed in the sterilized soil. Furthermore, possible transformation products (e.g., SE₂₃₉, E2₃₇₈, E1 dimer₅₃₈, E1-E2 dimer₅₄₁) of E1 and E1-3S in soil were analyzed and identified after the column transport experiments. The estrogenic activity was estimated by 17β-estradiol equivalency values during the transport process in aqueous and soil phases. Additionally, the potential leaching transport to groundwater of E1-3S requires further critical concern.

Microbial processing of autochthonous organic matter controls the biodegradation of 17α-ethinylestradiol in lake sediments under anoxic conditions

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.

Responses of steroid estrogen biodegradation to cyanobacterial organic matter biodegradability in the water column of a eutrophic lake

The co-occurrence of cyanobacterial harmful algal blooms and contaminants is an increasing environmental concern in freshwater worldwide. Our field investigations coupled with laboratory incubations demonstrated that the microbial degradation potential of 17β-estradiol (E2) with estrone as the intermediate was primarily driven by increased dissolved organic matter (DOM) in the water column of a cyanobacterial bloom. To explain the intrinsic contribution of cyanobacterial-derived DOM (C-DOM) to estrogen biodegradation, a combination of methods including bioassay, ultrahigh-resolution mass spectrometry, and microbial ecology were applied. The results showed that preferential assimilation of highly biodegradable structures, including protein-, carbohydrate-, and unsaturated hydrocarbon-like molecules sustained bacterial growth, selected for more diverse microbes, and resulted in greater estrogen biodegradation compared to less biodegradable molecules (lignin- and tannin-like molecules). The biodegradability of C-DOM decreased from 78% to 1%, whereas the E2 biodegradation rate decreased dramatically at first, then increased with the accumulation of recalcitrant, bio-produced lipid-like molecules in C-DOM. This change was linked to alternative substrate-induced selection of the bacterial community under highly refractory conditions, as suggested by the greater biomass-normalized E2 biodegradation rate after a 24-h lag phase. In addition to the increased frequency of potential degraders, such as Sphingobacterium, the network analysis revealed that C-DOM molecules distributed in high H/C (protein- and lipid-like molecules) were the main drivers structuring the bacterial community, inducing strong deterministic selection of the community assemblage and upregulating the metabolic capacity for contaminants. These findings provide strong evidence that estrogen biodegradation in eutrophic water may be facilitated by cyanobacterial blooms and provide a theoretical basis for ecological remediation of estrogen pollution.

Experimental and theoretical studies into the hydroxyl radical mediated transformation of propylparaben to methylparaben in the presence of dissolved organic matter surrogate

Dissolved humic and biogenic substances might be present in the aphotic zone and contribute to the fate of parabens in natural aquatic ecosystem under the fluctuation of water multi-parameters. Through the combination of batch tests with quantum chemical calculation, hydroxyl radical (•OH) mediated degradation of propylparaben (PP) to methylparaben (MP) has been confirmed in the present study. The interaction of dissolved oxygen with environmental relevant concentration of humic acid (HA), algal and bacterial cell lysis leads to a slow production of •OH. Aqueous PP undergoes a mild removal process with the pseudo-first order rate constant (10^-7, s^-1) higher at 7.43 in HA than at 3.30-4.89 in biogenic cell lysis. PP removal is correlated with the aromaticity of DOM surrogate and the produced •OH concentration, which could be enhanced by the increase of light intensity and DO other than HA. The •OH mediated process on PP removal has been confirmed by the linearly inhibited effect of tert-butanol while totally inhibited effects of higher concentration of sodium azide and co-existent chemical (17β-estradiol). Based on the detection of byproduct MP, two possible reaction pathways, •OH attacking at β-carbon (path-β) and terminal γ-carbon (path-γ) of the propyl side chain of PP, are proposed. Through the analysis of thermal and kinetics parameters, the •OH initiated H-abstraction and the resulting C-C bond cleavage leading to the formation of MP and acetaldehyde in path-β is confirmed to be the dominant reaction mechanism. Considering the universal occurrence of parabens and these DOM surrogates, this mild removal process has special implications for the self-purification of organic pollutants in natural aquatic ecosystems, especially in DOM-rich matrices in the aphotic zone.

Comparative responses of cell growth and related extracellular polymeric substances in Tetraselmis sp. to nonylphenol, bisphenol A and 17α-ethinylestradiol

Estuarine ecosystems near mega-cities are sinks of anthropogenic endocrine disrupting chemicals (EDCs). As the most important primary producer, indigenous microalgae and their secreted extracellular polymeric substances (EPSs) might interact with EDCs and contribute to their fate and risk. Tetraselmis sp. is a representative model of estuarine microalga, for which EDC toxicity and its effects on EPS synthesis have rarely been studied. Through microalgal isolation, algal cell growth tests, EDC removal and the characterization of related EPS profiles, the present work intends to clarify the comparative responses of Tetraselmis sp. to nonylphenol (NP), bisphenol A (BPA) and 17α-ethinylestradiol (EE₂). The results showed that the half inhibitory concentration on cell growth was 0.190-0.313 mg/dm³ for NP, which was one order of magnitude lower than the comparable values for BPA and EE₂ at 2.072-3.254 mg/dm³. Regarding chlorophyll, NP induced its degradation, EE₂ led to its decreased production, and BPA had no obvious effect. Under EDC stress, only the concentrations of colloidal polysaccharides and proteins responded dose-dependently to EE₂. Except for the colloidal fraction in the EE₂ treatment group, the increase in neutral monosaccharides, especially glucose and galactose, was a common response to EDCs. Compared to the recalcitrant BPA, NP underwent abiotic degradation in alga-free water, and EE₂ could be biodegraded in water containing this microalga. The chemical-specific responses of cell growth, chlorophyll and related EPS profiles were driven by the different fates of EDCs, and the underlying mechanism was further discussed. The results obtained in the present work are of critical importance for understanding the fate and effects of different EDCs mediated by microalgae and their related EPSs.

Recovery of subtropical coastal intertidal system prokaryotes from a destruction event and the role of extracellular polymeric substances in the presence of endocrine disrupting chemicals

Intertidal sediments constitute the micro-environment for the co-existence of endocrine disrupting chemicals (EDCs) and biofilms consisting of the microbial community and extracellular polymeric substances (EPS). However, the interactions and the resulting eco-function of this community are complex and poorly characterized, especially after a destruction event. This study evaluates the re-construction of biofilms in terms of the abundance of prokaryotic cells and related EPS characterization in two destroyed sedimentary matrices from subtropical environments simulated by sterilization in the presence of EDCs and investigates the role of EPS. The results show that benthic prokaryotes recover from the deposition of active prokaryotes in natural seawater and form biofilms after sterilization. Sterilization triggers the release of polysaccharides and protein from lysed native microbial cells and bound EPS in sedimentary organic matter, thus increasing their concentrations. The increased portion of EPS also acts as a persistent stress on re-colonizing prokaryotes and leads to the overproduction of sedimentary EPS. Due to the protective role mediated by EPS, the effect of EDCs on biofilm composition in sterilized sediment is not significant. The sedimentary matrix is the most important determinant of the composition of the biofilm and the occurrence of EDCs. At the end of an 84-day experiment, the abundance of prokaryotic cells and the concentrations of polysaccharides and protein in mangrove sediment are 1.6-1.8 times higher than those in sandflat sediment, regardless of EDCs. Sandflat sediment exhibits higher concentrations of nonylphenol and bisphenol A but a lower concentration of 17α-ethinylestradiol than mangrove sediment. This study enhances our understanding of the role of sedimentary biofilms and the fate of EDCs in intertidal systems and highlights the benefit of a destructive event in enhancing ecosystem function, particularly tolerance to EDC adversity due to EPS production.

Adsorptive removal of apramycin antibiotic from aqueous solutions using Tween 80-and Triton X-100 modified clinoptilolite: experimental and fixed-bed modeling investigations

This study examined the performance of natural clinoptilolite (NC) modified with two surfactants of Triton X-100 (NC-Triton) and Tween 80 (NC-Tween) on apramycin (APR) adsorption from wastewater in batch and continues systems. The optimum pH, contact time, adsorbent dosage, and temperature were achieved. The findings revealed that the sorption was best described using the Langmuir isotherm compared to other isotherms. The maximum adsorption capacity of NC-Triton was greater than NC and NC-Tween. The lumped method was applied to solve the fixed-bed equations; predict breakthrough curve; determine axial dispersion coefficient and overall mass transfer coefficient parameters; and compare theoretical results with experimental results. Good fitness of experimental data with kinetic models of intra-particle diffusion, pseudo-first-order/liquid film diffusion and pseudo-second-order for NC, NC-Tween and NC-Triton, respectively, indicated that they were more suitable than the other models. Endothermic and spontaneous processes were resulted from positive enthalpy and negative Gibbs free energy changes, respectively.

Priming effect of autochthonous organic matter on enhanced degradation of 17α-ethynylestradiol in water-sediment system of one eutrophic lake

Climate change and increasing eutrophication are expected to increase the release of autochthonous organic matter (OM) to sediments, where most contaminants are transformed or mineralized in freshwater lakes. This study sought to evaluate how cyanobacteria- and macrophyte-derived OM (COM and MOM) affected the microbial attenuation of 17α-ethinylestradiol (EE2) in the sediment from eutrophic Lake Taihu in China. In two months of water-sediment microcosm experiments, the input of COM and MOM both promoted EE2 degradation more strongly than humic acids, and the degradation efficiency was significantly and positively correlated with the cometabolism of increasing organic carbon in sediments (P < 0.001). The enhanced degradation was explained by responses of indigenous bacterial community to OM amendment as a priming effect. The immediate breakdown of biodegradable components such as proteinaceous substances in COM and MOM remarkably augmented the metabolic activity of bacteria in terms of the stimulated activity of extracellular enzymes including fluorescein diacetate and dehydrogenase, as well as the elevated production of proteins and polysaccharides in extracellular polymeric substances. In the meantime, the bacterial community composition was reshaped toward a more eutrophic state, leading to the clear upregulation of metabolic function genes of organic carbon and xenobiotics. Correlation-based network analysis further determined the strong facilitative coordination between the community members and the compositional variability of OM in the cometabolism. These results suggest that cyanobacterial blooms-dominated zones are potential hotspot areas for steroid estrogen attenuation, a finding of significance for the control and management of complex pollution in freshwater lakes.

A High Manganese-Tolerant Pseudomonas sp. Strain Isolated from Metallurgical Waste Heap Can Be a Tool for Enhancing Manganese Removal from Contaminated Soil

Manganese (Mn) is widely used in industry. However, its extensive applications have generated a great amount of manganese waste, which has become an ecological problem and has led to a decrease in natural resources. The use of microorganisms capable of accumulating Mn ions from contaminated ecosystems offers a potential alternative for the removal and recovery of this metal. The main aim of this work was an investigation of removal potential of Mn from soil by isolated bacterial. For this purpose, eleven bacterial strains were isolated from the soil from metallurgical waste heap in Upper Silesia, Poland. Strain named 2De with the highest Mn removal potential was selected and characterized taking into account its ability for Mn sorption and bioaccumulation from soil and medium containing manganese dioxide. Moreover, the protein profile of 2De strain before and after exposition to Mn was analyzed using SDS/PAGE technique. The 2De strain was identified as a Pseudomonas sp. The results revealed that this strain has an ability to grow at high Mn concentration and possesses an enhanced ability to remove it from the solution enriched with the soil or manganese dioxide via a biosorption mechanism. Moreover, changes in cellular protein expression of the isolated strain were observed. This study demonstrated that autochthonous 2De strain can be an effective tool to remove and recover Mn from contaminated soil.

Spatio-temporal distribution and transformation of 17α- and 17β-estradiol in sterilized soil: A column experiment

The environmental behaviors of steroid estrogens (SEs) associated with land irrigation and application are of critical concern worldwide. Understanding the spatio-temporal distribution and transformation process of these estrogenic compounds in soil is greatly significant. In this study, laboratory soil column experiments were conducted to investigate and explore the migration and abiotic transformation of 17α-estradiol (17α-E2) and 17β-estradiol (17β-E2) over spatial and time scales. Results indicated that the migration tendency of 17α-E2 and 17β-E2 was similar. Discrepancies in transport for different SEs groups might be due to the competitive sorption and isomeric transformation in the binary-solute system. 17α-E2 and 17β-E2 can also undergo the abiotic transformation during soil column transport. The soil with naturally abundant mineral substances (e.g., iron and manganese oxides) indicated that E2 isomers tended to mineral-promoted racemization, oxidation, reduction, and radical coupling reactions. Some possible transformation products (e.g., SE₂₃₉, E2₃₇₈, and SE dimer₄₇₆) were identified and proposed in soil samples. Compared to the single compound tests, the estimated 17β-estradiol equivalency (EEQ) values of E2 mixture were higher during SEs migration process.

A novel cobalt doped MOF-based photocatalyst with great applicability as an efficient mediator of peroxydisulfate activation for enhanced degradation of organic pollutants

A novel cobalt doped MOF-based photocatalyst was synthesized for the first time and employed as a mediator of peroxydisulfate activation for enhanced pollutant degradation.

Recent advances in the detection of 17β-estradiol in food matrices: A review

Pollution of endocrine disrupting chemicals has become a global issue. As one of the hormonally active compounds, 17β-estradiol produces the strongest estrogenic effect when it enters the organism exogenously including food intakes, bringing potential harmfulness such as malfunction of the endocrine system. Therefore, in order to assure food safety and avoid potential risks of 17β-estradiol to humans, it is of great significance to develop rapid, sensitive and selective approaches for the detection of 17β-estradiol in food matrices. In this review, the harmfulness and main sources of 17β-estradiol are firstly introduced, followed by the description of the principles and applications of different approaches for 17β-estradiol detection including high performance liquid chromatography, electrochemistry, Raman spectroscopy, fluorescence and colorimetry. Particularly, applications in detecting 17β-estradiol in food matrices over the years of 2010-2018 are discussed. Finally, advantages and limitations of these detection methods are highlighted and perspectives on future developments in the detection methods for 17β-estradiol are also proposed. Although many detection approaches can achieve trace or ultratrace detection of 17β-estradiol, further studies should be focused on the development of in-situ and real-time methods to monitor and evaluate 17β-estradiol for food safety.

Occurrence, sorption, and transformation of free and conjugated natural steroid estrogens in the environment

Natural steroid estrogens (NSEs), including free estrogens (FEs) and conjugated estrogens (CEs), are of emerging concern globally among public and scientific community due to their recognized adverse effects on human and wildlife endocrine systems in recent years. In this review, the properties, occurrence, sorption process, and transformation pathways of NSEs are clarified in the environment. The work comprehensively summarizes the occurrence of both free and conjugated estrogens in different natural and built environments (e.g., river, WWTPs, CAFOs, soil, and sediment). The sorption process of NSEs can be impacted by organic compounds, colloids, composition of clay minerals, specific surface area (SSA), cation exchange capacity (CEC), and pH value. The degradation and transformation of free and conjugated estrogens in the environment primarily involves oxidation, reduction, deconjugation, and esterification reactions. Elaboration about the major, subordinate, and minor transformation pathways of both biotic and abiotic processes among NSEs is highlighted. The moiety types and binding sites also would affect deconjugation degree and preferential transformation pathways of CEs. Notably, some intermediate products of NSEs still remain estrogenic potency during transformation process; the elimination of total estrogenic activity needs to be addressed in further studies. The in-depth researches regarding the behavior of both free and conjugated estrogens are further required to tackle their contamination problem in the ecosystem. Graphical abstract ᅟ.

Acidogenic bacteria assisted biodegradation of nonylphenol in waste activated sludge during anaerobic fermentation for short-chain fatty acids production

Nonylphenol (NP) biodegradation under anaerobic conditions is difficult. Here, enhancement of anaerobic NP biodegradation mainly by regulating the role of acidogenic bacteria during anaerobic fermentation of waste activated sludge (WAS) for short-chain fatty acids production is reported. The maximum degradation efficiency of NP (69.4%) was achieved under conditions of pH 10.0 and 10 mg/L Brij 35 within 8 d, which was nearly 3-fold of that in the control (24.6%). Mechanism exploration revealed that the bioavailability of NP and specific NP-degrading bacteria and their functional genes were advantageous to NP biodegradation with alkaline pH and surfactant. More importantly, acidogenic bacteria, the dominant functional bacteria in WAS fermentation systems, were demonstrated to be involved in NP anaerobic biodegradation by providing intermediate organic substrates, as well as through their intrinsic NP-degrading abilities. Possible pathways of NP biodegradation assisted by acidogenic bacteria during anaerobic fermentation were also proposed based on the detected metabolites.

Evaluation of the anaerobic biodegradation of linear alkylbenzene sulfonates (LAS) using OECD 308 water/sediment systems

Linear alkylbenzene sulfonates (LAS) are the most widely used anionic surfactants in household detergents and cleaning products. We have evaluated LAS anaerobic degradation in sediments following OECD 308 guidelines. Four different classes of sediments were collected from non-polluted areas and tested to check the influence of: fine and coarse texture, low and high organic carbon content, and freshwater and marine origin. The concentrations of LAS and possible degradation metabolites in sediment and water phases were monitored by high resolution mass spectrometry over an incubation period of 160 days. LAS removal was between 0 and 63%, depending on the sediment used, and it was accompanied by formation of sulfophenyl carboxylic acids (SPCs). The best results were observed for marine sediments having low organic carbon and silt + clay contents (0.5% and 13%, respectively), whereas degradation was negligible in freshwater sediments. The large differences in degradation observed across the sediments tested were attributed to their physicochemical properties influencing LAS bioavailability and the heterogeneity of microbial communities. Further research is also needed to address some shortcomings observed during the application of the OECD 308 and to ensure that test results obtained with these guidelines model anaerobic biodegradation under realistic environmental conditions.

Overproduction of microbial extracellular polymeric substances in subtropical intertidal sediments in response to endocrine disrupting chemicals

Microorganisms and their extracellular polymeric substances (EPS) in sediments are important in sediment stabilization and the fate of pollutants. However, how toxic organic pollutants affect bacteria and EPS in sediments, particularly in subtropical intertidal zones is poorly known. The present study aims to investigate the bacterial abundance and related EPS in simulated intertidal sandflat and mangrove sediments under the stress of endocrine disrupting chemicals (EDCs). Results showed that the temporal changes of the bacterial number in both sandflat and mangrove sediments were similar, increased from days 0 to 56 then became steady during the 84-days incubation. Bacteria exhibited an important role in the production of high molecular weight (HMW) EPS protein and the degradation of the low molecular weight (LMW) EPS protein. During incubation, the EPS polysaccharides changed from a colloidal-LMW fraction at the beginning to a more complex-HMW fraction at the end of the experiment. The increases in the concentration of HMW polysaccharides might contribute to sediment stabilization. Among different spiked EDCs, nonylphenol (NP) and 17α-ethinylestradiol (EE₂) tended to accumulate in both sandflat and mangrove sediments and posed stresses to bacterial growth, especially the latter sediment. The persistent EDCs promoted a higher production of EPS polysaccharides and proteins in both sediments when compared to the respective control, but the EPS in the sandflat sediment was mainly in the colloidal fraction while the bound fraction was more abundant in the mangrove sediment. The present results enhance our understanding of the effects of EDCs on sediment biofilms in intertidal systems. This study also demonstrates the significance of EPS polysaccharides and proteins in sediment stabilization and provides a fundamental basis for future microbiology studies.

Accelerated biodegradation of BPA in water-sediment microcosms with Bacillus sp. GZB and the associated bacterial community structure

Bisphenol A (BPA) is a synthetic chemical primarily used to produce polycarbonate plastics and epoxy resins. Significant industrial and consumer's consumption of BPA-containing products has contributed to extensive contamination in different environmental matrices. In this study, microcosms bioaugmented with Bacillus sp. GZB were constructed to investigate BPA biodegradation, identify the main bacterial community, and evaluate bacterial community responses in the microcosms. Under aerobic conditions, BPA was quickly depleted as a result of bioaugmentation with Bacillus sp. GZB in water-sediment contaminated with pollutants. The pollutants used were generally associated with the electronic wastes (mobile phones, computers, televisions) dismantling process. Adding BPA affected the bacterial community composition in the water-sediment. Furthermore, BPA biodegradation was enhanced by adding electron donors/co-substrates: humic acid, NaCl, glucose, and yeast extract. Metagenomic analysis of the total 16S rRNA genes from the BPA-degrading microcosms with bioaugmentation illustrated that the genera Bacillus, Thiobacillus, Phenylobacterium, and Cloacibacterium were dominant after a 7-week incubation period. A consortium of microorganisms from different bacterial genera may be involved in BPA biodegradation in electronic waste contaminated water-sediment. This study provides new insights about BPA bioaugmentation and bacterial ecology in the BPA-degrading environment.