Strategies for microbial bioremediation of environmental pollutants from industrial wastewater: A sustainable approach

Synergistic effects of surfactant biostimulation and indigenous fungal bioaugmentation for enhanced bioremediation of PAH-contaminated soils

Surfactant biostimulation and autochthonous fungal bioaugmentation have emerged as promising strategies for the bioremediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs). However, the mechanisms driving their combined effects remain poorly understood. This study investigates the degradation mechanisms associated with bioaugmentation using the indigenous fungus Aspergillus fumigatus LJD-29 and surfactant Tween 80. By employing stable-isotope probing and high-throughput sequencing, we comprehensively assessed these processes. In our study, the results demonstrate that both Aspergillus fumigatus LJD-29 and Tween 80 significantly enhanced the degradation efficiency of phenanthrene and modified the microbial community composition, particularly among active degraders. Extracellular enzymes were identified as key players in the phenanthrene transformation process. Tween 80 improved the bioavailability of phenanthrene, stimulating the growth of native PAH degraders, with Pseudonocardia emerging as a prominent genus. Although the combined surfactant-fungal treatment did not substantially increase terminal degradation efficiency due to limitations in phenanthrene bioavailability, it accelerated the degradation rate. Additionally, Tween 80 helped restore the microbial community structure disrupted by fungal bioaugmentation. These findings provide valuable insights into the mechanisms of surfactant biostimulation and indigenous fungal bioaugmentation, highlighting the potential of this integrated bioremediation strategy for managing PAH-contaminated soils.

Insights into the potential of Chlorella species in the treatment of hazardous pollutants from industrial effluent

Effluents from the industrial sector contain a wide range of contaminants in the medium; when they are insufficiently treated and discharged in the aquatic environment, they pollute aquatic matrices, causing deleterious effects on all the lifeforms. Industries such as tanneries, textiles, dairy, pharmaceuticals, paper and pulp, food processing, petrochemicals, iron, and steel generate wastewater containing a wide range of environmentally harmful contaminants. Chlorella species are robust species that can adapt and grow in extreme conditions and have remarkable stress response mechanism with good acclimatization and bioremediation properties. This review aims to provide new insights on the importance of Chlorella in the treatment of industrial effluents. It provides a comprehensive summary of investigations that have proved the potential of Chlorella vulgaris, Chlorella minutissima, Chlorella sorokiniana, Chlorella kessleri, Chlorella ellipsoidea, Chlorella emersonii, Chlorella pyrenoidosa in the elimination of contaminants. Furthermore, highlights the mechanisms that Chlorella undergo in the effluent medium towards the removal of various contaminants.

Harnessing the power of microbial consortia for the biodegradation of per- and polyfluoroalkyl substances: Challenges and opportunities

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants that pose significant risks to human health and ecosystems owing to their widespread use and resistance to degradation. This study examines the potential of microbial consortia as a sustainable and effective strategy for biodegrading PFAS. It highlights how these complex communities interact with various PFAS, including perfluorocarboxylic acids, perfluorosulfonic acids, fluorotelomer alcohols, and fluorotelomer-based precursors. Despite the potential of microbial consortia, several challenges impede their application in PFAS remediation, including effective microbial species identification, inherent toxicity of PFAS compounds, co-contaminants, complications from biofilm formation, diversity of environmental matrices, and competition with native microbial populations. Future research should focus on refining characterization techniques to enhance our understanding of microbial interactions and functions within consortia. Integrating bioinformatics and system biology will enable a comprehensive understanding of microbial dynamics and facilitate the design of tailored consortia for specific PFAS compounds. Furthermore, field applications and pilot studies are essential for assessing the real-world effectiveness of microbial remediation strategies. Ultimately, advancing our understanding and methodologies will lead to efficient biodegradation processes and positioning microbial consortia as viable solutions for PFAS-contaminated environments.

Metagenomic interrogation of urban Superfund site reveals antimicrobial resistance reservoir and bioremediation potential

AIMS

We investigate the bioremediation potential of the microbiome of the Gowanus Canal, a contaminated waterway in Brooklyn, NY, USA, designated a Superfund site by the US Environmental Protection Agency due to high concentrations of contaminants, including polychlorinated biphenyls, petrochemicals, and heavy metals.

METHODS AND RESULTS

We present a metagenomic analysis of the Gowanus Canal sediment, consisting of a longitudinal study of surface sediment and a depth-based study of sediment core samples. We demonstrate that the resident microbiome includes 455 species, including extremophiles across a range of saltwater and freshwater species, which collectively encode 64 metabolic pathways related to organic contaminant degradation and 1171 genes related to heavy metal utilization and detoxification. Furthermore, our genetic screening reveals an environmental reservoir of antimicrobial resistance markers falling within 8 different classes of resistance, as well as de-novo characterization of 2319 biosynthetic gene clusters and diverse groups of secondary metabolites with biomining potential.

CONCLUSION

The microbiome of the Gowanus Canal is a biotechnological resource of novel metabolic functions that could aid in efforts for bioremediation, AMR reservoir mapping, and heavy metal mitigation.

Salinity levels influence treatment performance and the activity of electroactive microorganisms in a microbial fuel cell system for wastewater treatment

There is growing interest in developing effective treatment technologies to mitigate the environmental impact of saline wastewater while also potentially recovering valuable resources from it. However, it remains largely unknown how different salinity levels impact treatment performance, energy generation, and the diversity and composition of electroactive microorganisms in MFCs treating real effluents such as urban wastewater. This study explores the impact of three salinity levels (3.5, 7, and 15 g/L NaCl) on current production, organic removal rates, and bacterial community dynamics in a continuous-flow microbial fuel cell (MFC) fed with urban wastewater. Using metagenomics and metatranscriptomics, we explored variations in the abundance and expression of extracellular electron transfer (EET) genes and those involved in other general metabolisms. We found that low salinity (3.5 g/L NaCl) enhanced both current production and organic removal efficiency compared to higher salinity levels. This improvement was linked to an increased abundance and activity of electroactive microorganisms, particularly taxa within the Ignavibacteria class, which possess genes coding for outer membrane cytochromes and porin cytochromes. Additionally, salinity influenced general metabolic genes and microbial community composition, with higher salinity levels limiting bacterial growth and diversity. This research provides valuable insights into the interplay between salinity stress and microbial adaptation, contributing to the optimization of MFC technologies for enhanced environmental and bioengineering applications.

Lignocellulose biosorbents: Unlocking the potential for sustainable environmental cleanup

Climate change, the overconsumption of fossil fuels, and rapid population and economic growth have collectively driven a growing emphasis on environmental sustainability and the need for effective resource management. Chemicals or materials not currently regulated are known as contaminants of emergent concern (CECs). Nevertheless, wastewater is thought to be its main source, and worries about its probable presence in the environment are growing due to its potential damage to human and environmental health. To counteract hazardous chemicals in wastewater and promote ecological sustainability, there has been a significant deal of interest in finding environmentally benign and renewable materials. Because of its constituents' distinct physical and chemical qualities, lignocellulose stands out among the many possibilities as the most appealing possibility for water cleanup. It is an abundant, biocompatible, and renewable substance. Sustainable social development requires wastewater cleanup using renewable lignocellulosic resources. However, the generation of lignocellulose-based materials is restricted by the byproducts that are produced and the complicated, expensive, and environmentally harmful synthetic process. It has been determined that biosorption on lignocellulosic wastes and by-products is a suitable substitute for the current technologies used to remove hazardous metal ions and dye from wastewater streams. Lignocellulose is highly effective at adsorbing heavy metals like arsenic (As), cadmium (Cd), copper (Cu), chromium (Cr), and lead (Pb). Beyond heavy metals, it can also capture various organic pollutants, that includes dyes (like methylene blue, methyl orange and malachite green), and pharmaceutical residues, and pesticides. Additionally, lignocellulosic materials are valuable for adsorbing oil and hydrocarbons from water, playing a crucial role in addressing environmental concerns related to oil spills. The pollutant removal efficiency of lignocellulose can be greatly improved through a range of physical, chemical, and biological modification methods, including thermal and ultrasound treatments, acid and alkali processing, ammoniation, amination, grafting, crosslinking, enzymatic modifications, and microbial colonization. In this article, we examine the most recent developments in lignocellulose-based adsorbent research, with an emphasis on lignocellulosic composition, adsorbent application, and material modification. A methodical and thorough presentation of the preparation and modification techniques for lignin, cellulose, and hemicellulose, as well as their utilization for treating various types of contaminated water, is provided. Additionally, a great resource for comprehending the specified adsorption mechanism and recycling of adsorbents is the thorough explanation of the mechanism of adsorption, the adsorbent renewal process, and the adsorption model.

Advances in environmental pollutant detection techniques: Enhancing public health monitoring and risk assessment

Accurate detection and monitoring of environmental pollutants are of paramount importance for disease prevention and public health. In recent years, the ever-expanding human activities and industrial production have given rise to a sharp increase in the complexity and variety of these pollutants, which pose significant threats to human well - being. Environmental pollutants stem from multiple sources, such as heavy metals, persistent organic pollutants, inorganic non - metallic pollutants, emerging pollutants, and biological contaminants. Traditional detection technologies, though valuable for their sensitivity and accuracy, are constrained by complex sample preparation, poor selectivity, and the absence of standardized detection methods. On the other hand, emerging technologies, including nanotechnology, molecular detection methods, biosensors, Surface-Enhanced Raman Spectroscopy (SERS), multi-omics, and big data analysis, offer promising solutions for rapid and sensitive pollutant detection. The establishment of environmental monitoring networks and data - sharing platforms further enhances real - time pollutant monitoring and provides solid data support for public health initiatives. Nonetheless, challenges persist, including data integration, exposure assessment, and the development of cost-effective and portable detection solutions. Future progress in interdisciplinary approaches and technology integration will be crucial for advancing environmental pollutant detection and facilitating comprehensive disease prevention. This review systematically classifies environmental pollutants and showcases the latest advancements in detection technologies, offering critical insights for environmental monitoring and public health protection.

Comprehensive approaches to heavy metal bioremediation: Integrating microbial insights and genetic innovations

The increasing contamination of ecosystems with heavy metals (HMs) due to industrial activities raises significant jeopardies to environmental health and human well-being. Addressing this issue, recent advances in the field of bioremediation have highlighted the potential of plant-associated microbiomes and genetically engineered organisms (GEOs) to mitigate HMs pollution. This review explores recent advancements in bioremediation strategies for HMs detoxification, with particular attention to omics technologies such as metagenomics, metabolomics, and metaproteomics in deepening the understanding of microbial interactions and their potential for neutralizing HMs. Additionally, Emerging strategies and technologies in GEOs and microorganism-aided nanotechnology have proven to be effective bioremediation tools, particularly for alleviating HM contamination. Despite the promising strategies developed in laboratory settings, several challenges impede their practical application, including ecological risks, regulatory limitations, and public concerns regarding the practice of genetically modified organisms. A comprehensive approach that involves interdisciplinary research is essential to enhance the efficacy and safety of bioremediation technologies. This approach should be coupled with robust regulatory frameworks and active public engagement to ensure environmental integrity and societal acceptance. This review underscores the importance of developing sustainable bioremediation strategies that align with ecological conservation goals and public health priorities.

Inoculum selection and hydraulic retention time impacts in a microbial fuel cell treating saline wastewater

Microbial fuel cell (MFC) technology has received increased interest as a suitable approach for treating wastewater while producing electricity. However, there remains a lack of studies investigating the impact of inoculum type and hydraulic retention time (HRT) on the efficiency of MFCs in treating industrial saline wastewater. The effect of three different inocula (activated sludge from a fish-canning industry and two domestic wastewater treatment plants, WWTPs) on electrochemical and physicochemical parameters and the anodic microbiome of a two-chambered continuous-flow MFC was studied. For each inoculum, three different HRTs were tested (1 day, 3 days, and 6 days). The inoculum from the fish canning industry significantly increased voltage production (with a maximum value of 802 mV), power density (with a maximum value of 78 mW m-2), coulombic efficiency (with a maximum value of 19.3%), and organic removal rate (ORR) compared to the inocula from domestic WWTPs. This effect was linked to greater absolute and relative abundances of electroactive microorganisms (e.g., Geobacter, Desulfovibrio, and Rhodobacter) and predicted electron transfer genes in the anode microbiome likely due to better adaption to salinity conditions. The ORR and current production were also enhanced at shorter HRTs (1 day vs. 3 and 6 days) across all inocula. This effect was related to a greater abundance and diversity of bacterial communities at HRT of 1 day compared to longer HRTs. Our findings have important bioengineering implications and can help improve the performance of MFCs treating saline effluents such as those from the seafood industry. KEY POINTS: • Inoculum type and HRT impact organic matter removal and current production. • Changes in bioenergy generation were linked to the electroactive anodic microbiome. • Shorter HRT favored increases in the performance of the MFC.

Modulation of Zn Ion Toxicity in Pisum sativum L. by Phycoremediation

Microalgae offer a promising alternative for heavy metal removal, and the search for highly efficient strains is ongoing. This study investigated the potential of two microalgae, Coelastrella sp. BGV (Chlorophyta) and Arthronema africanum Schwabe & Simonsen (Cyanoprokaryota), to bind zinc ions (Zn2⁺) and protect higher plants. Hydroponically grown pea (Pisum sativum L.) seedlings were subjected to ZnSO4 treatment for 7 days in either a nutrient medium (Knop) or a microalgal suspension. The effects of increasing Zn2⁺ concentrations were evaluated through solution parameters, microalgal dry weight, pea growth (height, biomass), and physiological parameters, including leaf gas exchange, chlorophyll content, and normalized difference vegetation index (NDVI). Zinc accumulation in microalgal and plant biomass was also analyzed. The results revealed that microalgae increased pH and oxygen levels in the hydroponic medium while enhancing Zn accumulation in pea roots. At low ZnSO4 concentrations (2-5 mM), microalgal suspensions stimulated pea growth and photosynthetic performance. However, higher ZnSO4 levels (10-15 mM) caused Zn accumulation, leading to nutrient deficiencies and growth suppression in microalgae, which ultimately led to physiological disturbances in peas. Coelastrella sp. BGV exhibited greater tolerance to Zn stress and provided a stronger protective effect when co-cultivated with peas, highlighting its potential for phycoremediation applications.

Biodegradation of azo dyes by Aspergillus flavus and its bioremediation potential using seed germination efficiency

The worldwide textile industry extensively uses azo dyes, which pose serious health and environmental risks. Effective cleanup is necessary but challenging. Developing bioremediation methods for textile effluents will improve color removal efficiency. The recent attention to effectively utilizing microbes to convert toxic industrial azo dyes into non-hazardous compounds has garnered significant attention. In the present study, four fungal strains-Aspergillus flavus, Aspergillus terreus, Aspergillus niger, and Fusarium oxysporium-were employed to screen for the degradation and detoxification of azo dyes including congo red, crystal violet, bromophenol blue, and malachite green. After eight days, A. flavus had degraded azo dyes at the maximum proportion. The maximum decolorization (%) was achieved at 50 mg/L of dye concentration, 8 days of incubation, pH 6, 30 °C temperature, sucrose as a carbon source, NaNO3 as a nitrogen source, Ca+2 as minerals, and using static culture. The efficient production of laccases, lignin peroxidase, and manganese peroxidase enzymes by A. flavus proved that the enzyme played a crucial role in decolorizing the harmful azo dyes. The Fourier Transform Infrared spectrometer (FT-IR) data validated the decolorization and degradation process brought on by absorption and biodegradation. Compared to control plants, the results of the phytotoxicity assay showed that the degraded product was less harmful to maize and common bean plant's growth and germination rates. As a result, the findings indicate that A. flavus is a viable option for remediating azo dyes. This aids in the biodegradation of azo dyes found in wastewater.

Agro-industrial wastes and their application perspectives in metal decontamination using biocomposites and bacterial biomass: a review

Contamination of water bodies is a significant global issue that results from the deliberate release of pollutants into the environment, especially from mining and metal processing industries. The main pollutants generated by these industries are metallic wastes, particularly metals, which can cause adverse effects on the environment and human health. Therefore, it is crucial to develop effective and sustainable approaches to prevent their discharge into the environment. Biofiltration is a technique used to remediate contaminated fluids using biological processes. Microorganisms and agro-industrial wastes have been used successfully as biosorbents. Hence, this review emphasizes the innovative use of agro-industrial waste reinforced with microbial biomass as bioadsorbents, highlighting their dual capacity for metal removal through various bioremediation mechanisms. The mechanisms at play in these biocomposite materials, which offer enhanced sustainability, are also analyzed. This study contributes to the advancement of knowledge by suggesting new strategies for integrating reinforced materials in biosorption processes, thus providing a novel perspective on the potential of lignocellulosic-based systems to improve decontamination efforts. On the other hand, it shows some studies where the optimization and scaling-up of biosorption processes are reported. Additionally, the implementation of multisystem approaches, leveraging multiple bioremediation techniques simultaneously, can further enhance the efficiency and sustainability of metal removal in contaminated environments.

Mycoremediation of heavy metals by Curvularia lunata from Buckingham Canal, Neelankarai, Chennai

The spread and mobilization of toxic heavy metals in the environment have increased to a harmful level in recent years as a result of the fast industrialization occurring all over the world to meet the demands of a rising population. This research aims to analyze and evaluate the mycoremediation abilities of fungal strains that exhibit tolerance to heavy metals, gathered from water samples at Buckingham Canal, Neelankarai, Chennai. Water samples were examined for heavy metal analysis, and the highest toxic heavy metals, Zn, Pb, Mn, Cu, and Cr, were recorded. Three fungal strains were isolated and named EBPL1000, EBPL1001, and EBPL1002 were selected by primary screening (100 ppm) for further studies. Out of three fungal isolates, EBPL1000 grew in all five heavy metal concentrations and showed 2100 ppm as the highest Maximum Tolerance Concentration toward Lead, 2000 ppm tolerance in Zinc and Manganese, 1700 ppm in Chromium, and 1500 ppm in copper, respectively. The fungal isolate EBPL1000 was identified as Curvularia lunata with 100% percentage identity and query coverage. The Biosorption result reveals that lead is the highest biosorbed heavy metal with 79.99% at 100 ppm concentration while copper is the lowest biosorbed with 24.11% heavy metal at 500 ppm concentration. The uptake of Manganese by Curvularia lunata biomass was the highest (5.64 mg/g) of all heavy metal's uptake at 100 ppm concentration. The lowest uptake of heavy metals was copper (0.43 mg/g) at 500 ppm concentration, and the growth profile study under heavy metals stress conditions shows the order of Pb > Mn > Zn > Cr > Cu at 60 h of time intervals at 100 ppm concentration. In addition to the research, FTIR analysis and Molecular Docking studies provide credence to the idea that Curvularia lunata has high biosorption potential and uptake or removal of toxic heavy metals at low cost and in an eco-friendly way from the contaminated environment.

Rapid screening of indigenous degrading microorganisms for enhancing in-situ bioremediation of organic pollutants-contaminated soil

Organic pollutants (OPs) have caused severe environmental contaminations in the world and aroused wide public concern. Autochthonous bioaugmentation (ABA) is considered a reliable bioremediation approach for OPs contamination. However, the rapid screening of indigenous degrading strains from in-situ environments remains a primary challenge for the practical application of ABA. In this study, 3,5,6-Trichloro-2-pyridinol (TCP, an important intermediate in the synthesis of various pesticides) was selected as the target OPs, and DNA stable isotope probing (DNA-SIP) combined with high-throughput sequencing was employed to explore the rapid screening of indigenous degrading microorganisms. The results of DNA-SIP revealed a significant enrichment of OTU557 (Cupriavidus sp.) in the 13C-TCP-labeled heavy DNA fractions, indicating that it is the key strain involved in TCP metabolism. Subsequently, an indigenous TCP degrader, Cupriavidus sp. JL-1, was rapidly isolated from native soil based on the analysis of the metabolic substrate spectrum of Cupriavidus sp. Furthermore, ABA of strain JL-1 demonstrated higher remediation efficacy and stable survival compared to the exogenous TCP-degrading strain Cupriavidus sp. P2 in in-situ TCP-contaminated soil. This study presents a successful case for the rapid acquisition of indigenous TCP-degrading microorganisms to support ABA as a promising strategy for the in-situ bioremediation of TCP-contaminated soil.

Evaluation of the immobilized enzymes function in soil remediation following polycyclic aromatic hydrocarbon contamination

The bioremediation of polycyclic aromatic hydrocarbon (PAHs) from soil utilizing microorganisms, enzymes, microbial consortiums, strains, etc. has attracted a lot of interest due to the environmentally friendly, and cost-effective features. Enzymes can efficiently break down PAHs in soil by hydroxylating the benzene ring, breaking the C-C bond, and catalyze the hydroxylation of a variety of benzene ring compounds via single-electron transfer oxidation. However, the practical application is limited by its instability and ease to loss function under harsh environmental conditions such as pH, temperature, and edaphic stress etc. Therefore, this paper focused on the techniques used to immobilize enzymes and remediate PAHs in soil. Moreover, previous research has not adequately covered this topic, despite the employment of several immobilized enzymes in aqueous solution cultures to remediate other types of organic pollutants. Bibliometric analysis further highlighted the research trends from 2000 to 2023 on this field of growing interest and identified important challenges regarding enzyme stability and interaction with soil matrices. The findings indicated that immobilized enzymes may catalyzed PAHs via oxidation of OH groups in benzene rings, and generate benzyl radicals (i.e., •OH and •O2) that undergo further reaction and release water. As a result, the intermediate products of PAHs further catalyze by enzyme and enzyme induced microbes producing carbon dioxide and water. Meanwhile efficiency, activity, lifetime, resilience, and sustainability of immobilized enzyme need to be further improved for the large-scale and field-scale clean-up of PAHs polluted soils. This could be possible by integrating enzyme-based with microbial and plant-based remediation strategies. It can be coupled with another line of research focused on using a new set of support materials that can be derived from natural resources.

Development of Variable Charge Cationic Hydrogel Particles with Potential Application in the Removal of Amoxicillin and Sulfamethoxazole from Water

Cationic hydrogel particles (CHPs) crosslinked with glutaraldehyde were synthesized and characterized to evaluate their removal capacity for two globally consumed antibiotics: amoxicillin and sulfamethoxazole. The obtained material was characterized by FTIR, SEM, and TGA, confirming effective crosslinking. The optimal working pH was determined to be 6.0 for amoxicillin and 4.0 for sulfamethoxazole. Under these conditions, the CHPs achieved over 90.0% removal of amoxicillin after 360 min at room temperature, while sulfamethoxazole removal reached approximately 60.0% after 300 min. Thermodynamic analysis indicated that adsorption occurs through a physisorption process and is endothermic. The ΔH° values of 28.38 kJ mol-1, 12.39 kJ mol-1, and ΔS° 97.19 J mol-1 K-1, and 33.94 J mol-1 K-1 for AMX and SMX, respectively. These results highlight the potential of CHPs as promising materials for the removal of such contaminants from aqueous media.

Deletion of pyoverdine-producing pvdA increases cadmium stabilization by Pseudomonas umsongensis CR14 in cadmium-polluted solutions

In this study, the effects of the Cd-resistant and pyoverdine-producing strain Pseudomonas umsongensis CR14 on Cd stabilization and the mechanisms were investigated. Compared with the control, CR14 markedly reduced the Cd concentration in a Cd-containing solution. The genes pvdA, 4498, 4499, and pchF, which are associated with pyoverdine production, were identified in CR14. Subsequently, CR14 and the CR14ΔpvdA, CR14Δ4498, CR14Δ4499, and CR14ΔpchF mutants were characterized for their effects on Cd stabilization in solution. After 72 h of incubation, the CR14ΔpchF and CR14ΔpvdA mutants significantly decreased Cd concentrations compared with CR14. Notably, the CR14ΔpvdA mutant showed a greater impact on Cd stabilization than the other mutants. Compared with CR14, this mutant brought a lower Cd concentration in the solution, with higher levels of cell surface-adsorbed and intracellular accumulated Cd, content of lipopolysaccharide (LPS), expression of the LPS-producing genes lptD and lpxL, and cell surface particles. Additionally, compared with CR14, the CR14ΔpvdA mutant demonstrated increased interactions between the hydroxyl, carboxyl, amino, or ether groups and Cd. These results suggest that the CR14ΔpvdA mutant immobilized Cd by increasing LPS production and cell surface particle numbers, upregulating the expression of LPS-producing genes, and increasing cell surface adsorption and intracellular accumulation in Cd-polluted solutions.

Aerogels based on Bacterial Nanocellulose and their Applications

Microbial cellulose stands out for its exceptional characteristics in the form of biofilms formed by highly interlocked fibrils, namely, bacterial nanocellulose (BNC). Concurrently, bio-based aerogels are finding uses in innovative materials owing to their lightweight, high surface area, physical, mechanical, and thermal properties. In particular, bio-based aerogels based on BNC offer significant opportunities as alternatives to synthetic or mineral counterparts. BNC aerogels are proposed for diverse applications, ranging from sensors to medical devices, as well as thermal and electroactive systems. Due to the fibrous nanostructure of BNC and the micro-porosity of BNC aerogels, these materials enable the creation of tailored and specialized designs. Herein, a comprehensive review of BNC-based aerogels, their attributes, hierarchical, and multiscale features are provided. Their potential across various disciplines is highlighted, emphasizing their biocompatibility and suitability for physical and chemical modification. BNC aerogels are shown as feasible options to advance material science and foster sustainable solutions through biotechnology.

Genetic Adaptations and Mechanistic Insights Into Bacterial Bioremediation in Ecosystems

Metal pollution poses significant threats to the ecosystem and human health, demanding effective remediation strategies. Bioremediation, which leverages the unique metal-resistant genes found in bacteria, offers a cost-effective and efficient solution to heavy metal contamination. Genes such as Cad, Chr, Cop, and others provide pathways to improve the detoxification of the ecosystem. Through multiple techniques, genetic engineering makes bacterial genomes more capable of improving metal detoxification; nonetheless, there are still unanswered questions regarding the nature of new metal-resistant genes. This article examines bacteria's complex processes to detoxify toxic metals, including biosorption, bioaccumulation, bio-precipitation, and bioleaching. It also explores essential genes, proteins, signaling mechanisms, and bacterial biomarkers involved in breaking toxic metals.

Bio-inspired magnetic chitosan/Iron oxide macromolecules for multiple anionic dyes adsorption from aqueous media

Organic anionic dyes are major water pollutants due to their low degradability caused by complex aromatic structures. Not only do they exert toxic, mutagenic, teratogenic, tumorigenic, and genotoxic effects, but they also decrease fertility and cause irritation to the skin and respiratory system in humans. This long-term toxicity has detrimental effects on aquatic organisms and their surroundings, resulting in an imbalanced ecosystem. In this study, a Cs@Fe3O4 magnetic biosorbent was synthesised to uptake three anionic dyes and characterised for FTIR, BET/BJH, XRD, TGA, VSM, and FESEM analyses. The biosorbent average surface area was confirmed to be 52.6524 m2/g, with average pore sizes of 7.3606 nm and 6.9823 nm for adsorption-desorption processes, respectively. Batch adsorption studies pH values, contact times, temperature, initial dye concentrations, and adsorbent dosages were examined. Several isotherm and kinetic models were studied to determine the adsorption mechanism. The adsorption data of these dyes at equilibrium was observed to match Langmuir's isotherm and pseudo-second-order kinetic models. The thermodynamic study revealed that the adsorption process for these dyes was an exothermic reaction. Maximum adsorption capacities for congo red, methyl orange, and metanil yellow were 117.77 mg/g, 137.77 mg/g, and 155.57 mg/g, respectively. The reusability of recovered Cs@Fe3O4 after dye adsorption was evaluated up to five continuous adsorption-desorption cycles for its possible industrial applications.

Three strategy rules of filamentous fungi in hydrocarbon remediation: an overview

Remediation of hydrocarbon contaminations requires much attention nowadays since it causes detrimental effects on land and even worse impacts on aquatic environments. Tools of bioremediation especially filamentous fungi permissible for cleaning up as much as conceivable, at least they turn into non-toxic residues with less consumed periods. Inorganic chemicals, CO2, H2O, and cell biomass are produced as a result of the breakdown and mineralization of petroleum hydrocarbon pollutants. This paper presents a detailed overview of three strategic rules of filamentous fungi in remediating the various aliphatic, and aromatic hydrocarbon compounds: utilizing carbons from hydrocarbons as sole energy, Co-metabolism manners (Enzymatic and Non-enzymatic theories), and Biosorption approaches. Upliftment in the degradation rate of complex hydrocarbon by the Filamentous Fungi in consortia scenario we can say, "Fungal Talk", which includes a variety of cellular mechanisms, including biosurfactant production, biomineralization, and precipitation, etc., This review not only displays its efficiency but showcases the field applications - cost-effective, reliable, eco-friendly, easy to culture as biomass, applicable in both land and any water bodies in operational environment cleanups. Nevertheless, the potentiality of fungi-human interaction has not been fully understood, henceforth further studies are highly endorsed with spore pathogenicity of the fungal species capable of high remediation rate, and the gene knockout study, if the specific peptides cause toxicity to any living matters via Genomics and Proteomics approaches, before application of any in situ or ex situ environments.

Modern perspectives of heavy metals alleviation from oil contaminated soil: A review

Heavy metal poisoning of soil from oil spills causes serious environmental problems worldwide. Various causes and effects of heavy metal pollution in the soil environment are discussed in this article. In addition, this study explores new approaches to cleaning up soil that has been contaminated with heavy metals as a result of oil spills. Furthermore, it provides a thorough analysis of recent developments in remediation methods, such as novel nano-based approaches, chemical amendments, bioremediation, and phytoremediation. The objective of this review is to provide a comprehensive overview of the removal of heavy metals from oil-contaminated soils. This review emphasizes on the integration of various approaches and the development of hybrid approaches that combine various remediation techniques in a synergistic way to improve sustainability and efficacy. The study places a strong emphasis on each remediation strategy that can be applied in the real-world circumstances while critically evaluating its effectiveness, drawbacks, and environmental repercussions. Additionally, it discusses the processes that reduce heavy metal toxicity and improve soil health, taking into account elements like interactions between plants and microbes, bioavailability, and pollutant uptake pathways. Furthermore, the current study suggests that more research and development is needed in this area, particularly to overcome current barriers, improve our understanding of underlying mechanisms, and investigate cutting-edge ideas that have the potential to completely transform the heavy metal clean up industry.

Microbes' role in environmental pollution and remediation: a bioeconomy focus approach

Bioremediation stands as a promising solution amid the escalating challenges posed by environmental pollution. Over the past 25 years, the influx of synthetic chemicals and hazardous contaminants into ecosystems has required innovative approaches for mitigation and restoration. The resilience of these compounds stems from their non-natural existence, distressing both human and environmental health. Microbes take center stage in this scenario, demonstrating their ability of biodegradation to catalyze environmental remediation. Currently, the scientific community supports a straight connection between biorefinery and bioremediation concepts to encourage circular bio/economy practices. This review aimed to give a pre-overview of the state of the art regarding the main microorganisms employed in bioremediation processes and the different bioremediation approaches applied. Moreover, focus has been given to the implementation of bioremediation as a novel approach to agro-industrial waste management, highlighting how it is possible to reduce environmental pollution while still obtaining value-added products with commercial value, meeting the goals of a circular bioeconomy. The main drawbacks and challenges regarding the feasibility of bioremediation were also reported.

Bioprospecting of extremophilic perchlorate-reducing bacteria: report of promising Bacillus spp. isolated from sediments of the bay of Cartagena, Colombia

Three extremophile bacterial strains (BBCOL-009, BBCOL-014 and BBCOL-015), capable of degrading high concentrations of perchlorate at a range of pH (6.5 to 10.0), were isolated from Colombian Caribbean Coast sediments. Morphological features included Gram negative strain bacilli with sizes averaged of 1.75 × 0.95, 2.32 × 0.65 and 3.08 × 0.70 μm, respectively. The reported strains tolerate a wide range of pH (6.5 to 10.0); concentrations of NaCl (3.5 to 7.5% w/v) and KClO4- (250 to 10000 mg/L), reduction of KClO4- from 10 to 25%. LB broth with NaCl (3.5-30% w/v) and KClO4- (250-10000 mg/L) were used in independent trials to evaluate susceptibility to salinity and perchlorate, respectively. Isolates increased their biomass at 7.5 % (w/v) NaCl with optimal development at 3.5 % NaCl. Subsequently, ClO4- reduction was assessed using LB medium with 3.5% NaCl and 10000 mg/L ClO4-. BBCOL-009, BBCOL-014 and BBCOL-015 achieved 10%, 17%, and 25% reduction of ClO4-, respectively. The 16 S rRNA gene sequence grouped them as Bacillus flexus T6186-2, Bacillus marisflavi TF-11 (T), and Bacillus vietnamensis 15 - 1 (T) respectively, with < 97.5% homology. In addition, antimicrobial resistance to ertapenem, vancomycine, amoxicillin clavulanate, penicillin, and erythromycin was present in all the isolates, indicating their high adaptability to stressful environments. The isolated strains from marine sediments in Cartagena Bay, Colombia are suitable candidates to reduce perchlorate contamination in different environments. Although the primary focus of the study of perchlorate-reducing and resistant bacteria is in the ecological and agricultural realms, from an astrobiological perspective, perchlorate-resistant bacteria serve as models for astrobiological investigations.

The complete degradation of 1,2-dichloroethane in Escherichia coli by metabolic engineering

1,2-Dichloroethane (1,2-DCA), a widely utilized chemical intermediate and organic solvent in industry, frequently enters the environment due to accidental leaks and mishandling during application processes. Thus, the in-situ remediation of contaminated sites has become increasingly urgent. However, traditional remediation methods are inefficient and costly, while bioremediation presents a green, efficient, and non-secondary polluting alternative. In this study, an engineered strain capable of completely degrading 1,2-DCA was constructed. We introduced six exogenous genes of the 1,2-DCA degradation pathway into E. coli and confirmed their normal transcription and efficient expression in this engineered strain through qRT-PCR and proteomics. The degradation experiments showed that the strain completely degraded 2 mM 1,2-DCA within 12 h. Furthermore, the results of isotope tracing verified that the final degradation product, malic acid, entered the tricarboxylic acid cycle (TCA) of E. coli and was ultimately fully metabolized. Also, morphological changes in the engineered strain and control strain exposed to 1,2-DCA were observed under SEM, and the results revealed that the engineered strain is more tolerant to 1,2-DCA than the control strain. In conclusion, this study paved a new way for humanity to deal with the increasingly complex environmental challenges.

Reduction of Toxic Metal Ions and Production of Bioelectricity through Microbial Fuel Cells Using Bacillus marisflavi as a Biocatalyst

Industrialization has brought many environmental problems since its expansion, including heavy metal contamination in water used for agricultural irrigation. This research uses microbial fuel cell technology to generate bioelectricity and remove arsenic, copper, and iron, using contaminated agricultural water as a substrate and Bacillus marisflavi as a biocatalyst. The results obtained for electrical potential and current were 0.798 V and 3.519 mA, respectively, on the sixth day of operation and the pH value was 6.54 with an EC equal to 198.72 mS/cm, with a removal of 99.08, 56.08, and 91.39% of the concentrations of As, Cu, and Fe, respectively, obtained in 72 h. Likewise, total nitrogen concentrations, organic carbon, loss on ignition, dissolved organic carbon, and chemical oxygen demand were reduced by 69.047, 86.922, 85.378, 88.458, and 90.771%, respectively. At the same time, the PDMAX shown was 376.20 ± 15.478 mW/cm2, with a calculated internal resistance of 42.550 ± 12.353 Ω. This technique presents an essential advance in overcoming existing technical barriers because the engineered microbial fuel cells are accessible and scalable. It will generate important value by naturally reducing toxic metals and electrical energy, producing electric currents in a sustainable and affordable way.

Innovative remediation strategies for persistent organic pollutants in soil and water: A comprehensive review

Persistent organic pollutants (POPs) provide a serious threat to human health and the environment in soil and water ecosystems. This thorough analysis explores creative remediation techniques meant to address POP pollution. Persistent organic pollutants are harmful substances that may withstand natural degradation processes and remain in the environment for long periods of time. Examples of these pollutants include dioxins, insecticides, and polychlorinated biphenyls (PCBs). Because of their extensive existence, cutting-edge and environmentally friendly eradication strategies must be investigated. The most recent advancements in POP clean-up technology for soil and water are evaluated critically in this article. It encompasses a wide range of techniques, such as nanotechnology, phytoremediation, enhanced oxidation processes, and bioremediation. The effectiveness, cost-effectiveness, and environmental sustainability of each method are assessed. Case studies from different parts of the world show the difficulties and effective uses of these novel techniques. The study also addresses new developments in POP regulation and monitoring, highlighting the need of all-encompassing approaches that include risk assessment and management. In order to combat POP pollution, the integration of diverse remediation strategies, hybrid approaches, and the function of natural attenuation are also examined. Researchers, legislators, and environmental professionals tackling the urgent problem of persistent organic pollutants (POPs) in soil and water should benefit greatly from this study, which offers a complete overview of the many approaches available for remediating POPs in soil and water.

Treatment of marble industry wastewater by Brassica napus (L.) under oxalic acid amendment: efficacy as fodder and carcinogenic risk assessment

In the present study, Brassica napus, a food plant, was grown for phytoextraction of selected heavy metals (HMs) from marble industry wastewater (WW) under oxalic acid (OA) amendment. The hydroponic experiment was performed under different combination of WW with OA in complete randomized design. Photosynthetic pigments and growth reduction were observed in plants treated with WW alone amendments. The combination of OA in combination with WW significantly enhanced the growth of plants along with antioxidant enzyme activities compared with WW-treated-only plants. HM stress alone enhanced the hydrogen peroxide, electrolyte leakage, and malondialdehyde contents in plants. OA-treated plants were observed with enhanced accumulation of cadmium (Cd), copper (Cu), and lead (Pb) concentrations in the roots and shoots of B. napus. The maximum concentration and accumulation of Cd in root, stem, and leaves was increased by 25%, 30%, and 30%; Cu by 42%, 24%, and 17%; and Pb by 45%, 24%, and 43%, respectively, under OA amendment. Average daily intake and hazard quotient (HQ) were calculated for males, females, and children in two phases of treatments in phytoremediation of metals before and after accumulation into B. napus leaves and stems. HQ of metals in the leaves and stem was < 1 before metal accumulation, whereas > 1 was observed after HM accumulation for all males, females, and children. Similarly, the hazard index of the three study types was found > 1. It was observed that the estimated excess lifetime cancer risk was of grade VII (very high risk), not within the accepted range of 1 × 10-4 to 1 × 10-6. Based on the present study, the increased levels of HMs up to carcinogenicity was observed in the B. napus which is not safe to be consumed later as food.

Effects of heavy metals and metalloids on the biodegradation of organic contaminants

Heavy metals and metalloids (HMMs) inhibit the biodegradation of organic pollutants. The degree of inhibition depends not only on the concentration and bioavailability of HMMs but also on additional factors, such as environmental variables (e.g., inorganic components, organic matter, pH, and redox potential), the nature of the metals, and microbial species. Based on the degradation pattern and metal concentrations causing half biodegradation rate reductions (RC50s), the inhibition of biodegradation was: Hg2+, As2O3 > Cu2+, Cd2+, Pb2+, Cr3+ > Ni2+, Co2+ > Mn2+, Zn2+ > Fe3+. Four patterns were observed: inhibition increases with increasing metal concentration; low concentrations stimulate, while high concentrations inhibit; high concentrations inhibit less; and mild inhibition remains constant. In addition, metal ion mixtures have more complex inhibitory effects on the degradation of organic pollutants, which may be greater than, similar to, or less than that of individual HMMs. Finally, the inhibitory mechanism of HMMs on biodegradation is reviewed. HMMs generally have little impact on the biodegradation pathway of organic pollutants for bacterial strains. However, when pollutants are biodegraded by the community, HMMs may activate microbial populations harbouring different transformation pathways. HMMs can affect the biodegradation efficiency of organic pollutants by changing the surface properties of microbes, interfering with degradative enzymes, and interacting with general metabolism.

Combining fungal bioremediation and ozonation for rinse wastewater treatment

In this work, agricultural rinse wastewater, which is produced during the cleaning of agricultural equipment and constitutes a major source of pesticides, was treated by fungal bioremediation and ozonation, both individually and combined in a two-stage treatment train. Three major pesticides (thiacloprid, chlortoluron, and pyrimethanil) were detected in rinse wastewater, with a total concentration of 38.47 mg C L-1. Comparing both technologies, ozonation in a stirred reactor achieved complete removal of these pesticides (720 min) while proving to be a more effective approach for reducing colour, organic matter, and bacteria. However, this technique produced transformation products and increased toxicity. In contrast, fungal bioremediation in a rotating drum bioreactor attenuated toxicity levels and did not produce such metabolites, but only removed approximately 50 % of target pesticide - hydraulic retention time (HRT) of 5 days - and obtained worse results for most of the general quality parameters studied. This work also includes a preliminary economic assessment of both technologies, revealing that fungal bioremediation was 2 times more cost-effective than ozonation. The treatment train, consisting of a first stage of fungal bioremediation followed by ozonation, was found to be a promising approach as it synergistically combines the advantages of both treatments, achieving high removals of pesticides (up to 100 %) and transformation products, while reducing operating costs and producing a biodegradable effluent. This is the first time that fungal bioremediation and ozonation technologies have been compared and combined in a treatment train to deal with pesticides in agricultural rinse wastewater.

Bioremediation of environmental organic pollutants by Pseudomonas aeruginosa: Mechanisms, methods and challenges

The development of the chemical industry has led to a boom in daily consumption and convenience, but has also led to the release of large amounts of organic pollutants, such as petroleum hydrocarbons, plastics, pesticides, and dyes. These pollutants are often recalcitrant to degradation in the environment, whereby the most problematic compounds may even lead to carcinogenesis, teratogenesis and mutagenesis in animals and humans after accumulation in the food chain. Microbial degradation of organic pollutants is efficient and environmentally friendly, which is why it is considered an ideal method. Numerous studies have shown that Pseudomonas aeruginosa is a powerful platform for the remediation of environmental pollution with organic chemicals due to its diverse metabolic networks and its ability to secrete biosurfactants to make hydrophobic substrates more bioavailable, thereby facilitating degradation. In this paper, the mechanisms and methods of the bioremediation of environmental organic pollutants (EOPs) by P. aeruginosa are reviewed. The challenges of current studies are highlighted, and new strategies for future research are prospected. Metabolic pathways and critical enzymes must be further deciphered, which is significant for the construction of a bioremediation platform based on this powerful organism.

Effect of Micro-Nanobubbles on Arsenic Removal by Trichoderma atroviride for Bioscorodite Generation

The global environmental issue of arsenic (As) contamination in drinking water is a significant problem that requires attention. Therefore, the aim of this research was to address the application of a sustainable methodology for arsenic removal through mycoremediation aerated with micro-nanobubbles (MNBs), leading to bioscorodite (FeAsO4·2H2O) generation. To achieve this, the fungus Trichoderma atroviride was cultivated in a medium amended with 1 g/L of As(III) and 8.5 g/L of Fe(II) salts at 28 °C for 5 days in a tubular reactor equipped with an air MNBs diffuser (TR-MNBs). A control was performed using shaking flasks (SF) at 120 rpm. A reaction was conducted at 92 °C for 32 h for bioscorodite synthesis, followed by further characterization of crystals through Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray diffraction (XRD) analyses. At the end of the fungal growth in the TR-MNBs, the pH decreased to 2.7-3.0, and the oxidation-reduction potential (ORP) reached a value of 306 mV at 5 days. Arsenic decreased by 70%, attributed to possible adsorption through rapid complexation of oxidized As(V) with the exchangeable ferrihydrite ((Fe(III))4-5(OH,O)12), sites, and the fungal biomass. This mineral might be produced under oxidizing and acidic conditions, with a high iron concentration (As:Fe molar ratio = 0.14). The crystals produced in the reaction using the TR-MNBs culture broth and characterized by SEM, XRD, and FTIR revealed the morphology, pattern, and As-O-Fe vibration bands typical of bioscorodite and römerite (Fe(II)(Fe(III))2(SO4)4·14H2O). Arsenic reduction in SF was 30%, with slight characteristics of bioscorodite. Consequently, further research should include integrating the TR-MNBs system into a pilot plant for arsenic removal from contaminated water.

Biological and green remediation of heavy metal contaminated water and soils: A state-of-the-art review

Contamination of the natural ecosystem by heavy metals, organic pollutants, and hazardous waste severely impacts on health and survival of humans, animals, plants, and microorganisms. Diverse chemical and physical treatments are employed in many countries, however, the acceptance of these treatments are usually poor because of taking longer time, high cost, and ineffectiveness in contaminated areas with a very high level of metal contents. Bioremediation is an eco-friendly and efficient method of reclaiming contaminated soils and waters with heavy metals through biological mechanisms using potential microorganisms and plant species. Considering the high efficacy, low cost, and abundant availability of biological materials, particularly bacteria, algae, yeasts, and fungi, either in natural or genetically engineered (GE) form, bioremediation is receiving high attention for heavy metal removal. This report comprehensively reviews and critically discusses the biological and green remediation tactics, contemporary technological advances, and their principal applications either in-situ or ex-situ for the remediation of heavy metal contamination in soil and water. A modified PRISMA review protocol is adapted to critically assess the existing research gaps in heavy metals remediation using green and biological drivers. This study pioneers a schematic illustration of the underlying mechanisms of heavy metal bioremediation. Precisely, it pinpoints the research bottleneck during its real-world application as a low-cost and sustainable technology.

Microbial biosorbent for remediation of dyes and heavy metals pollution: A green strategy for sustainable environment

Toxic wastes like heavy metals and dyes are released into the environment as a direct result of industrialization and technological progress. The biosorption of contaminants utilizes a variety of biomaterials. Biosorbents can adsorb toxic pollutants on their surface through various mechanisms like complexation, precipitation, etc. The quantity of sorption sites that are accessible on the surface of the biosorbent affects its effectiveness. Biosorption’s low cost, high efficiency, lack of nutrient requirements, and ability to regenerate the biosorbent are its main advantages over other treatment methods. Optimization of environmental conditions like temperature, pH, nutrient availability, and other factors is a prerequisite to achieving optimal biosorbent performance. Recent strategies include nanomaterials, genetic engineering, and biofilm-based remediation for various types of pollutants. The removal of hazardous dyes and heavy metals from wastewater using biosorbents is a strategy that is both efficient and sustainable. This review provides a perspective on the existing literature and brings it up-to-date by including the latest research and findings in the field.

Performance of a Combined Bacteria/Zeolite Permeable Barrier on the Rehabilitation of Wastewater Containing Atrazine and Heavy Metals

Several chemicals, such as pesticides and heavy metals, are frequently encountered together in environment matrices, becoming a priority concerning the prevention of their emissions, as well as their removal from the environment. In this sense, this work aimed to evaluate the effectiveness of a permeable biosorbent bio-barrier reactor (PBR) on the removal of atrazine and heavy metals (copper and zinc) from aqueous solutions. The permeable bio-barrier was built with a bacterial biofilm of R. viscosum supported on 13X zeolite. One of the aims of this work is the investigation of the toxic effects of atrazine, copper and zinc on the bacterial growth, as well as the assessment of their ability to adapt to repeated exposure to contaminants and to degrade atrazine. The growth of R. viscosum was not affected by concentrations of atrazine bellow 7 mg/L. However, copper and zinc in binary solutions were able to inhibit the growth of bacteria for all the concentrations tested (5 to 40 mg/L). The pre-acclimation of the bacteria to the contaminants allowed for an increase of 50% of the bacterial growth. Biodegradation tests showed that 35% of atrazine was removed/degraded, revealing that this herbicide is a recalcitrant compound that is hard to degrade by pure cultures. The development of a PBR with R. viscosum supported on zeolite was successfully performed and the removal rates were 85% for copper, 95% for zinc and 25% for atrazine, showing the potential of the sustainable and low-cost technology herein proposed.