Xenobiotic Organic Compounds Research Articles

Revealing the comprehensive impact of organic compounds on the partial nitrification-anammox system during incineration leachate treatment: metabolic hierarchy and adaptation

Organics, as widespread pollutants in high-strength ammonia wastewater, typically exert adverse effects on the performance of partial nitrification-anammox (PNA) systems. However, the in-depth knowledge on how microbial consortia respond to these disturbances remains limited. In this study, we unveiled the evolution of complex organic matter flow and its impact on the metabolic hierarchy and adaptation of microbial consortia, employing multi-omics approaches, i.e., 16S amplicon sequencing, metagenomics, and metabolomics. In a two-stage PNA system sequentially treating synthetic wastewater and incineration leachate over 230 days, partial nitrification stayed stable (nitrite accumulation > 97%) while anammox efficiency dropped (nitrogen removal decreased from 86% to 78%). The phenomenon was revealed to be correlated with the evolution of dissolved organic matter (DOM) and xenobiotic organic compounds (XOCs). In the PN stage, ammonia-oxidizing bacteria (AOB) exhibited excellent adaptability through active metabolic regulation after treating leachate. Numerous heterotrophs proliferated to utilize DOM and XOCs, triggering a “boom” state evident in the glycerophospholipid metabolism. However, in the anammox stage, the competition between carbon fixation and central carbon metabolism within autotrophs and heterotrophs became evident. Increased biosynthesis costs inhibited the central metabolism (specific anammox activity decreased by 66%) and the Wood-Ljungdahl pathway of anammox bacteria (AnAOB) in the presence of recalcitrant organics. Additionally, the degradation of organics was limited, exhibiting a “bust” state. This study revealed the metabolic adaption and susceptibility of AOB and AnAOB in response to organics from the leachate, demonstrating the applicability of the two-stage configuration for treating high-strength wastewater containing abundant and diverse organics.

Removal of hydrophilic, hydrophobic, and charged xenobiotic organic compounds from greywater using green wall media

Green walls offer a novel on-site approach for greywater treatment and reuse in densely build urban environments. However, they need to be engineered for effective removal of a wide range of emerging contaminants such as xenobiotic organic compounds (XOCs), which may be present in greywater due to extensive use of personal care products and household chemicals. This study used laboratory column design and batch experiments to investigate the performance of three lightweight green wall media (coco coir, zeolite, and perlite) and their mixture in three different combinations for the removal of twelve XOCs, covering wide range of hydrophilic, hydrophobic, and charged pollutants in greywater. The experiments were designed to assess the removal of targeted XOCs under different operational condition (i.e., hydraulic loading, infiltration rate, drying) and uncover the dominant mechanisms of their removal. Results showed excellent removal (>90%) of all XOCs in coco coir and media mix columns at the start of the experiment (i.e., fresh media and initial 2 pore volume (PV) of greywater dosing). The removal of highly hydrophobic and positively charged XOCs remained high (>90%) under all operational conditions, while hydrophilic and negatively charged XOCs exhibited significant reduction in removal after 25 PV and 50 PV, possibly due to their low adsorption affinity and electrostatic repulsion from negatively charged media. The effect of infiltration rate on the removal of XOCs was not significant; however, higher removal was achieved after 2-weeks of drying in coco coir and media mix columns. The dominant removal mechanism for most XOCs was found to be adsorption, however, a few hydrophilic XOCs (i.e., acetaminophen and atrazine) exhibited both adsorption and biodegradation removal processes. While findings showed promising prospects of unvegetated media for removing XOCs from greywater, long term studies on vegetated green wall systems are needed to understand any synergetic contribution of plants and media in removing these XOCs.

Isolation and Characterization of Potential Potassium Solubilizing Bacteria with Various Plant Growth Promoting Traits

In soil, microorganisms participate in diverse processes such as C, N, P and S conversion, breakdown of xenobiotic organic compounds, soil structure development and plant nutrient uptake intensification. Plant growth promoting rhizobacteria (PGPR) serve as biofertilizer in both direct and indirect ways. In this study, two potassium solubilizing bacteria strains designated as AKY2 and HPY10 were isolated from rhizospheric soil. The bacterial isolate HPY10 was characterized as Serratia marcescens by using 16s rRNA sequencing. The potassium solubilisation index of strain HPY10 was 3.2. The potassium released by isolates AKY2 and HPY10 was 7.29 and 8.66 mg/L after 10 days of incubation respectively. Both isolates were showing different plant growth promoting activity. The present study, suggests use of isolates AKY2 and HPY10 as biofertilizers which is beneficial for crop cultivation by enhancing growth and yield due to the production of phosphate solubilization, IAA (indole-3-acetic acid) and also having antagonistic potential against Fusarium oxysporum.

Eliminating xenobiotics organic compounds from greywater through green synthetic nanoparticles

Xenobiotic Organic Compounds (XOCs) have been widely considered to be pollutant compounds due to their harmful impacts on aquatic life. However, there have been few rigorous studies of cutting-edge technology used to eradicate XOCs and their presence in bathroom greywater. The present review provides a comprehensive examination of current methodologies used for removing XOCs by photocatalysis of green nanoparticles. It was appeared that zinc oxide nanoparticles (ZnO NPs) have high efficiency (99%) in photocatalysis process. Green synthesis provides proven processes that do not require dangerous chemicals or expensive equipment, making photocatalysis a potential solution for the status quo. XOCs residue was decomposed, and pollutants were eliminated with varied degrees of efficiency using green synthesis ZnO nanoparticles. It is hypothesized that the utilization of photocatalysis can create a greywater treatment system capable of degrading the toxic XOCs in greywater while increasing the pace of production. Hence, this review will be beneficial in improving greywater quality and photocatalysis using green nanoparticles can be an immediate platform in solving the issue regarding the existence of XOCs in greywater in Malaysia. Researchers in the future may benefit from focusing on optimizing photocatalytic degradation using green-synthesis ZnO. It might also help with the creativity and productivity of the next generation of authoritative concerns, notably water conservation.

Treatment of landfill leachate using advanced oxidation process and struvite precipitation processes

Landfill leachate contains high organic matter, heavy metals, ammonia and xenobiotic compounds. It requires potential treatment prior to its discharge. Several treatment methods are reported in the literature with low Chemical Oxygen Demand (COD) and ammonia concentration but most of them were inefficient to treat landfill leachate. In this view, Advanced Oxidation Processes (AOP’s) in combination with chemical precipitation are considered to be more suitable for high COD and ammonia. In this study, an attempt was made to evaluate the application of Fenton and Struvite Precipitation processes for the removal of COD and ammonia. The operational parameters for Fenton and Struvite are optimized. The individual treatment processes by Fenton and struvite achieved % removal of 60% and 25%, 30% and 65% of COD and ammonia respectively. The Fenton and struvite processes were performed in a sequence with the pre-optimized parameters, where the maximum removal of COD and ammonia is observed as 89% and 78%. The kinetic analysis of struvite process fits into the first order kinetics. Hence, the combined fenton process and struvite precipitation processes are reliable, efficient and can be considered as an alternative treatment for the traditional treatment methods thereby reducing its toxicity.

Influence of sewage sludge stabilization method on microbial community and the abundance of antibiotic resistance genes

Municipal sewage sludge (MSS) and other biosolids are of high interest for agriculture. These nutrient-rich organic materials can potentially serve as organic fertilizers. Besides an increase of organic matter in soil, other positive effects were shown after their application. Especially the positive influence on circular economy increased the attention paid to management of MSS in recent years. Unfortunately, the use of sewage sludge has some drawbacks. Biosolids are frequently polluted with heavy metals, xenobiotic organic compounds and industrial chemicals, which may be hazardous for the environment and humans. Here, we investigated the influence of stabilization method and the size of wastewater treatment plant on the structure of microbial communities as well as the abundance of antibiotic resistance genes (ARG) and mobile genetic elements (MGE). All tested ARG and MGE were detectable in almost all of the samples. Interestingly, the presence of MGE as well as particular heavy metals correlated positively with the presence of several ARG. We conclude that the distribution of ARG and MGE in biosolids originated from municipal wastewater treatment plants, cannot be explained by the size of the facility or the applied stabilization method. Moreover, we postulate that the presence of pollutants and long-term impacts should be assessed prior to a possible use of sewage sludge as fertilizer.

55 xenobiotic organic compounds in Tripoli landfill-Lebanon leachate and their fluxes to the Abou Ali River and Mediterranean Sea.

Pollution generated from landfill solid wastes constitute one of the major threat to the environment. The landfill leachate contains various toxic pollutants, making it the most dangerous issue of the landfills. Monitoring the xenobiotic organic concentrations in landfill leachate is an important step to evaluate the environmental impacts. This work aims to characterize the seasonal variation of 55 xenobiotic organic compounds including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalic acid esters (PAEs) and bisphenols (BPs) in the leachate from municipal solid waste landfill of Tripoli, Lebanon. And also, the quantity of the pollutant's flux to the Abou Ali River and the Mediterranean Sea nearby has been estimated. The organic pollutants were extracted by using the solid-phase extraction and quantified by using GC-MS/MS. The results showed high level of PAEs, BPs, PCBs, and PAHs in the leachate samples. The fluxes of pollutants to the Abou Ali River and Mediterranean Sea have been detected at 0.23kg, 0.01kg, 116.85kg, 15.93kg, and 7.58kg for Σ16PAHs, Σ28PCBs, Σ6PAEs, Σ4BPs, and 4-NP respectively.

The comparative performance of lightweight green wall media for the removal of xenobiotic organic compounds from domestic greywater

Green walls can provide an aesthetic approach to treat domestic greywater in urban landscapes. However, the widespread adoption of green walls for greywater treatment depends on its performance to remove the emerging contaminants from greywater such as xenobiotic organic compounds (XOCs). In this study, the performance of five lightweight green wall media types (zeolite, perlite, date seeds, coffee grinds, and coco coir) was evaluated for the removal of six XOCs representing a range of hydrophilic to hydrophobic organic micropollutants in domestic greywater (acetaminophen, diethyltoluamide, bisphenol A, oxybenzone, triclosan, nonylphenol). The adsorption affinity of targeted XOCs on different green wall media types, the role of contact time on XOCs removal, and the impact of background pollutants in greywater matrix on the adsorption of XOCs were analysed. Results indicate that removal of XOCs was higher using carbonaceous waste materials (date seeds, coffee grinds, and coco coir) as compared to natural minerals (zeolite and perlite). Moreover, the adsorption of XOCs increased with the increase in pollutant hydrophobicity. All XOCs showed highest removal using coco coir with fast adsorption kinetics, achieving 90% of the removal in 30 min. The only exception was acetaminophen that showed best removal using zeolite but exhibited slow adsorption kinetics with 90% of the removal attained in 24 h. The initial adsorption kinetics (<30 min) of XOCs in greywater were adversely affected by the presence of background pollutants, indicating the need of higher residence time of greywater in green wall system for better removal of XOCs. Based on the findings of this batch study, it is recommended to design a green wall system with more than 30 min of greywater residence time using a mixture of coco coir and zeolite for effective removal of XOCs from domestic greywater.

Xenobiotic Organic Compounds in a Landfill Leachate

Landfilling is a predominant method of waste disposal in most of the countries. Amongst the disadvantages of landfills use is the generation of gas and leachate which can possibly lead to the contamination of groundwater. Thus, examining of hazardous constituents of leachate such as xenobiotic organic compounds (XOCs) is essential to contain any unwanted impacts on the environment. In this study, leachate samples were collected from Al Amirat un engineered landfill in Muscat in order to examine the presence of XOCs. The results have showed the presence of some kinds of polychlorinated biphenyls (PCBs), pesticides, BTEX (benzene, toluene, ethyl benzene, xylene) and phthalates in low quantities. The concentrations of XOCs were only a small fraction of the total carbon content of leachate, but environmentally relevant leachate pollution levels were estimated to persist for decades to centuries. Thus, leachate should be collected regularly by means of newly constructed boreholes to avoid any risk to the environment. Such old un engineered landfills need to be well capped and rehabilitated to minimize their impacts on the environment.

Utility of lignin‐modifying enzymes: a green technology for organic compound mycodegradation

AbstractOrganic compounds such as heavy metals, polychlorinated biphenyls, petroleum hydrocarbons, pesticides and phenolic derivatives have become major environmental pollutants. These compounds are also known as xenobiotics as they are not produced or essentially utilized by any organism for its biological function. Xenobiotics are degraded by many microorganisms owing to the presence of enzymes that break down these complex compounds and utilize them as substrates. One group of enzymes commonly produced by microorganisms that have a major role in the degradation of xenobiotic organic compounds are lignin‐modifying enzymes, as the chemical structure of xenobiotic compounds resembles lignin. Lignin‐modifying enzymes are oxidative enzymes that have an important role in degrading abundant lignocellulosic wastes present in the environment. These enzymes include laccase, lignin peroxidase, manganese‐dependent peroxidase and versatile peroxidase, and are produced by bacteria and fungi, with white rot fungi being the major producer. They have a wide range of applications in detoxification of industrial and agricultural wastes and xenobiotic organic compounds. Mycodegradation or fungal degradation forms an important part of the ecosystem, as fungi can degrade many toxic substances because the fungal mycelia penetrate deep into substrates and help colonize the substrates rapidly. In this review, the problems associated with xenobiotic compounds are explained. Fungal lignin‐modifying enzymes, as a probable solution to xenobiotic degradation, have also been discussed in detail, along with their mechanism of action. © 2021 Society of Chemical Industry (SCI).

Photocatalysis of xenobiotic organic compounds in greywater using zinc oxide nanoparticles: a critical review

AbstractThe direct discharge of raw bathroom greywater has increased the concentrations of various pollutants in the water bodies. Typically, greywater contains large quantities of xenobiotic organic compounds (XOCs) owing to an increase in consumption of personal care and bath products. Therefore, it urges for a suitable technology to eliminate these compounds from contaminated waters. Photocatalytic degradation using Zinc Oxide nanoparticles (ZnO NPs) has the potentiality to eliminate various XOCs. However, ZnO NPs have high tendency to aggregate, which may lower the photocatalytic degradation rate. Therefore, there is an urgency to modify ZnO NPs to overcome the limitation. The present review was conducted to determine a suitable method for the modification ZnO NPs. Besides, the potential of the modified ZnO NPs in degrading XOCs in greywater as a photocatalyst was also discussed.

Characterization of segregated greywater from Indian households-part B: emerging contaminants.

Emerging contaminants (ECs) have become an increasing area of concern due to the likely impacts of these compounds on human health and the environment. Generally, products which are used for households and personal care activities contribute to major percentage of ECs in household greywater. Not much information on the presence of xenobiotic organic compounds in greywater is currently available. Therefore, the present study focused on the qualitative and quantitative analyses of emerging contaminants from different classifications of Indian households. The qualitative screening of emerging pollutants by solid-phase extraction-gas chromatography and mass spectroscopy (SPE-GC-MS) showed the presence of 78 different emerging contaminants from three different sources, which are categorized into ten different groups based on their chemical properties. The quantitative analysis of few selected target pollutants such as phthalic esters, namely diethyl hexyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, triclosan, bisphenol A, caffeine, acetaminophen, 3-methyl salicylic acid, 4-octylphenol, and 4-nonylphenol were found to be 0.38 ± 0.39 μg/L, 1.57 ± 1.54 μg/L, 4.77 ± 2.57 μg/L, 0.712 ± 0.17 μg/L, 5.82 ± 1.85 μg/L, 11.08 ± 2.64 μg/L, 2.30 ± 1.19 μg/L 13.18 ± 4.48 μg/L, 3.75 ± 1.90 μg/L, 4.95 ± 2.21 μg/L, and 5.96 μg/L, respectively. Risk assessment indicated that 63 compounds identified in the greywater can be considered priority pollutants. Based on the results obtained in the present study, effective zero-discharge liquid system can be designed for different sources of greywater and it can be recycled and reused without much risk. Graphical abstract .

Waste-derived biochar: Applications and future perspective in microbial fuel cells

Application of microbial fuel cell (MFC) is coming to the forefront as a dual-purpose system for wastewater treatment and energy recovery. Future research should emphasize on developing low-cost field-scale MFCs for removal of organic matter, nutrients, xenobiotic and recalcitrant compounds from wastewaters and powering low energy devices. For achieving this, low-cost electrodes, low-cost yet efficient cathode catalysts and proton exchange membrane (PEM) should be developed from waste-based resources to salvage the waste-derived material as much as possible, thereby reducing the fabrication cost of this device. Biochar is one such low-cost material, which has wide range of applications. This review discusses different applications of biochar in MFC, viz. in the form of standalone electrodes, electrocatalyst and material for PEM in light of different characteristics of biochar. Further emphasis is given on the future direction of research for implementation of biochar-based PEMs and electrodes in field-scale MFCs.

A novel CuO/Fe2O3/ZnO composite for visible-light assisted photocatalytic oxidation of Bisphenol A: Kinetics, degradation pathways, and toxicity elimination

The present study presents a highly efficient, visible light-induced photocatalytic degradation of Bisphenol A (BPA) by a CuO/Fe2O3/ZnO composite, synthesized using a sol-gel combustion method. The catalyst was characterized by XRD, SEM, BET, EDX, DRS, TEM, and XPS techniques. The synthesized CuO/Fe2O3/ZnO catalyst was found to perform optimally at neutral pH and 0.04 g/L catalyst dosage, while H2O2 addition initiated further radical degradation pathways. HCO3− and NO3− in the water had a negative effect on BPA degradation, but SO42−, Cl− and PO43− demonstrated a significant increase in reaction kinetics, thus allowing a real-water application. Radical scavenger tests revealed that hydroxyl radicals and holes play the main role in BPA degradation and mineralization. Toxicity tests and probit analysis showed a significant decrease of LC50 on Daphnia Magna neonates. Considering the exceptional characteristics and photocatalytic performance of CuO/Fe2O3/ZnO under visible light, its application could be an efficient alternative for the degradation of xenobiotic organic compounds from polluted waters.

ABC transporters in gills of rainbow trout (Oncorhynchus mykiss).

Fish gills are a structurally and functionally complex organ at the interface between the organism and the aquatic environment. Gill functions include the transfer of organic molecules, both natural ones and xenobiotic compounds. Whether the branchial exchange of organic molecules involves active transporters is currently not known. Here, we investigated the presence, diversity and functional activity of ATP-binding cassette (ABC) transporters in gills of juvenile rainbow trout. By means of RT-qPCR, gene transcripts of members from the abcb, abcc and abcg subfamilies were identified. Comparisons with mRNA profiles from trout liver and kidney revealed that ABC transporters known to have an apical localization in polarized epithelia, especially abcc2 and abcb1, were under-represented in the gills. In contrast, ABC transporters with mainly basolateral localization showed comparable gene transcript levels in the three organs. The most prominent ABC transporter in gills was an abcb subfamily member, which was annotated as abcb5 based on the synteny and phylogeny. Functional in vivo assays pointed to a role of branchial ABC transporters in branchial solute exchange. We further assessed the utility of primary gill cell cultures to characterize transporter-mediated branchial exchange of organic molecules, by examining ABC transporter gene transcript patterns and functional activity in primary cultures. The gill cultures displayed functional transport activity, but the ABC mRNA expression patterns were different to those of the intact gills. Overall, the findings of this study provide evidence for the presence of functional ABC transporter activity in gills of fish.

Effect of Myclobutanil Pesticide on the Physiological Behavior of Two Newly Isolated Saccharomyces cerevisiae Strains during Very-High-Gravity Alcoholic Fermentation.

Yeasts are able to act as biosorbents, as their cell wall includes several components capable of binding organic xenobiotic compounds that can potentially be removed during various fermentation processes. In the present investigation, two novel Saccharomyces cerevisiae strains (LMBF-Y 16 and LMBF-Y-18), previously isolated from grapes, were studied regarding their physiological behavior (dry cell weight—DCW production, substrate uptake, and ethanol and glycerol biosynthesis) during fermentations of grape must, in some cases enriched with commercial glucose and fructose (initial total sugar concentration approximately 150 and 250 g/L, respectively). Myclobutanil (a chiral triazole fungicide broadly used as a protective agent of vine) was also added to the culture media at various concentrations in order to assess the ability of the yeasts to simultaneously perform alcoholic fermentations and detoxify the medium (i.e., to remove the fungicide). In the first set of experiments and for both tested strains, trials were carried out in either 250 mL or 2.0 L agitated shake flasks in either synthetic glucose-based experiments or grape musts. Since the results obtained in the trials where the cultures were placed in 2.0 L flasks with grape musts as substrates were superior in terms of both DCW and ethanol production, these experimental conditions were selected for the subsequent studies. Both strains showed high fermentative efficiency, producing high amounts of DCW (9.5–10.5 g/L) in parallel with high ethanol production, which in some cases achieved values very close to the maximum theoretical ethanol production yield (≈0.49 g of ethanol per g of sugar). When using grape must with initial total sugars at approximately 250 g/L (very high gravity fermentation media, close to winemaking conditions), significantly high ethanol quantities (i.e., ranging between 105 and 123 g/L) were produced. Myclobutanil addition slightly negatively affected sugar conversion into ethanol; however, in all cases, ethanol production was very satisfactory. A non-negligible myclobutanil removal during fermentation, which ranged between 5%–27%, as a result of the adsorptive or degradative capacity of the yeast was also reported. The presence of myclobutanil had no effect on DCW production and resulted in no significant differences in the biosynthesis of glycerol. Therefore, these newly isolated yeast strains could be excellent candidates for simultaneous high ethanol production and parallel pesticide removal in a general biorefinery concept demonstrating many environmental benefits.

New stormwater priority pollutants: comparison with international classifications, quality criteria and monitoring programs

Stonnwater discharges are generated by rain runoff from land and impervious areas such asroads, parking lots, and roofs during rainfall and snowmelt events. It contains an array ofdifferent pollutants such as organic matter, particles, heavy metals, inorganic trace elementsand xenobiotic organic compounds (XOCs). It is important to consider the hazards concerningthese pollutants when considering design of monitoring strategies, comparing differenthandling strategies for stonnwater utilisation, treatment methods and discharge to receivingwaters.In the EU 5FP funded Daywater project a list of selected stonnwater priority pollutants(SSPP) was identified, which has been used for assessing pollutant sources and fluxes,behaviour and fate during passage through best management practices (BMPs) and theenvironmental risk associated with their subsequent dispersal. The methodology used;Chemical Hazard Identification and Assessment Tool (CHIAT) aims at selecting relevantSSPP e.g. and can be used for development and evaluation of monitoring programmes.The Daywater SSPP-list consists of water quality parameters (BOD, COD, SS, nitrogen, pHand phosphorus); metals (Cd, Cr, Cu, Ni, Pb, Pt and Zn); PAHs (naphthalene, pyrene andbenzo[a]pyrene); herbicides (pendimethalin, phenmedipham, glyphosate and terbutylazine);and other XOCs (nonylphenol ethoxylates, pentachlorophenol, di(2-ethylhexyl)phthalate,PCB-28 and MTBE) representing persistent, ubiquitous compounds and compounds derivingfrom specific anthropogenic sources.The list was compared with data found within the Danish nation-wide monitoringprogrammes for the aquatic environment (NOV A2003 and NOV ANA); European monitoringprogrammes; pollutant registers; individual European legislation; as well as quality criteriaand limit values. The comparison reveals differences since most of these are set on arbitrarycriteria or focuses on the current EU legislation. Overlaps was found with the studiedprogrammes, but also some "new" compounds was selected; platinum, herbicides and MTBEwhich indicate that revision of existing monitoring programmes is needed and that stonnwatercontains more hazardous pollutants than previously anticipated.

Soil tillage and compost amendment promote bioremediation and biofertility of polluted area

Abstract The risk for human health and environment due to the presence in agricultural soils of organic and inorganic contaminants derived from illegal waste disposal, posed the need to develop a sustainable strategy for the restoration of soils with high agricultural potential. In this study an eco-compatible method as soil tillage and compost amendment was applied in two sites of a National Interest Priority Site of Campania Region (Italy) known as “Terra dei Fuochi”. After one year, the concentration of heavy hydrocarbons (C > 12) significantly reduced in a range from 84 to 95%, probably due to the aeration causing photo-oxidation processes and an improvement of microbial activity able to degrade organic pollutants. Although a reduction trend was observed, the potentially toxic elements (PTEs) concentration in soils was unmodified indicating a potential risk of plant uptake. The high-throughput sequencing approach used to explore the response of native microbial populations following in situ treatments showed that microbiota dynamic was differently affected in the two sites. Therefore, the characteristics of the sites could differently interact with compost determining a different microbial response. Alphaproteobacteria (incidence range of 14–18%), Actinobacteria (incidence range of 10–22%) and Sordariomycetes (incidence range of 23–57%) were the dominant autochthonous populations in all soils indicating their high adaptability to different environments and high resistance to environmental stress as well as their high potential in degradation of organic xenobiotic compounds. The remediation practices based on soil tillage and compost amendment promoted the restoration of the microbial biofertility of soils affected by spotted multi-contamination, to bring them back to agricultural use.

In situ transformation of ethoxylate and glycol surfactants by shale-colonizing microorganisms during hydraulic fracturing.

In the last decade, extensive application of hydraulic fracturing technologies to unconventional low-permeability hydrocarbon-rich formations has significantly increased natural-gas production in the United States and abroad. The injection of surface-sourced fluids to generate fractures in the deep subsurface introduces microbial cells and substrates to low-permeability rock. A subset of injected organic additives has been investigated for their ability to support biological growth in shale microbial community members; however, to date, little is known on how complex xenobiotic organic compounds undergo biotransformations in this deep rock ecosystem. Here, high-resolution chemical, metagenomic, and proteomic analyses reveal that widely-used surfactants are degraded by the shale-associated taxa Halanaerobium, both in situ and under laboratory conditions. These halotolerant bacteria exhibit surfactant substrate specificities, preferring polymeric propoxylated glycols (PPGs) and longer alkyl polyethoxylates (AEOs) over polyethylene glycols (PEGs) and shorter AEOs. Enzymatic transformation occurs through repeated terminal-end polyglycol chain shortening during co-metabolic growth through the methylglyoxal bypass. This work provides the first evidence that shale microorganisms can transform xenobiotic surfactants in fracture fluid formulations, potentially affecting the efficiency of hydrocarbon recovery, and demonstrating an important association between injected substrates and microbial growth in an engineered subsurface ecosystem.

Myco-Remediation of Xenobiotic Organic Compounds for a Sustainable Environment: A Critical Review

In this article, the utilization of fungi for the degradation of xenobiotic organic compounds (XOCs) from different wastewater and aqueous solutions has been reviewed. The myco-remediation (myco-enzymes, myco-degradation, and myco-sorption) process is widely used to remove XOCs, which are not easily biodegradable. The removal of XOCs from textile wastewaters through chemical and physical processes has been addressed by many researchers. Currently, the application of oxidative enzymes [manganese peroxidase (MnP), lignin peroxidase (LiP), and laccase] and myco-adsorption is becoming more common for the removal of XOCs from wastewater. Although the advanced oxidation process (AOPs) is a preferred technology for removing XOCs, its use is restricted due to its relatively high cost, which led to research studies on non-traditional and low-cost technology. The current review aimed to organize the scattered available information on the potential of myco-remediation for XOC removal. Moreover, the utilization of agricultural wastes as a production substrate for oxidative enzymes has been reported by many authors. Agricultural waste materials are highly inducible for oxidative enzyme production by fungi and are cost-effective in comparison to commercial substances. It is evident from the literature survey of 80 recently published papers that myco-enzymes have demonstrated outstanding XOC removal capabilities. Fungal laccase enzyme is the first step to degrade the lignin and then to get the carbon source form the cellulose by cellulose enzyme.