Exploring the role of microbes for the management of persistent organic pollutants

Microbial augmented aerobic composting for effective phthalates degradation in activated sludge

Phthalate esters (PAEs) accumulated in activated sludge posed serious threats to agroecosystems and environment. Traditional aerobic (AE) and anaerobic (AN) composting were limited in achieving sustained PAEs degradation due to the single structure of microbial community. Here, the effectiveness and microbiological mechanisms of bacterial-augmented aerobic composting (AEB) in reducing activated sludge PAEs were investigated, with comparison of anaerobic composting (ANB). Results showed that AEB treatments significantly enhanced PAEs degradation efficiency through batch degradation experiments and microbial community analysis. At initial PAEs contamination levels of 50 mg/kg and 100 mg/kg, di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) removal rates increased by 2.11-3.93-fold and 2.18-3.36-fold, respectively. Notably, AEB treatment reshaped bacterial community structure, forming communities dominated by efficient PAEs-degrading bacteria. Network analysis revealed a more complex microbial interaction networks under AE treatment, with the numbers of node and connectivity being 1.5 and 1.8 times than that of AN treatment. Functional gene prediction indicated increased abundances of PAEs degradation-related functional groups. Environmental factor analysis demonstrated optimized conditions through pH control, oxygen supply, and active carbon-nitrogen metabolism. These findings provided important supports for safe activated sludge disposal and resource utilization.

Combatting pesticide pollution: using liquid scintillation spectrometry to assess 14C-labeled hexachlorobenzene removal by mangrove Bacillus spp

This study explored the ability of two Bacillus species isolated from mangrove sediments to degrade hexachlorobenzene (HCB), a persistent organic pollutant that affects the quality of surface water, groundwater, and soil. Hence, we analyzed bacterial growth in a medium with hexachlorobenzene as the sole carbon source. Moreover, chemical oxygen demand removal, ecotoxicity, and measured radiolabeled HCB degradation were assessed. Our results revealed that both Bacillus strains (I3 and I6) demonstrated hexachlorobenzene-degrading potential and achieved degradation rates of 11.5 ± 1.47% and 21.1 ± 0.84%. Additionally, the ability of these strains to mineralize HCB was confirmed by the production of radiolabeled carbon dioxide, assessed by liquid scintillation spectrometry and thin-layer chromatography. Ecotoxicity assays further demonstrated the effectiveness of bacteria treatment in degrading HCB. These findings underscore the potential of Bacillus strains from mangrove sediments to degrade and mineralize HCB, opening new perspectives for the bioremediation of aromatic compounds in contaminated environments.

Diffuse soil pollution from agriculture: Impacts and remediation

Agricultural activities are essential for sustaining the global population, yet they exert considerable pressure on the environment. A major challenge we face today is agricultural pollution, much of which is diffuse in nature, lacking a clear point of origin for chemical discharge. Modern agricultural practices, which often depend on substantial applications of fertilizers, pesticides, and irrigation water, are key contributors to this form of pollution. These activities lead to downstream contamination through mechanisms such as surface runoff, leaching, soil erosion, wind dispersal, and sedimentation. The environmental and human health consequences of diffuse pollution are profound and cannot be ignored. Accurate assessment of the risks posed by agricultural pollutants is crucial for ensuring the production of safe, high-quality food while safeguarding the environment. This requires systematic monitoring and evaluation of agricultural practices, including soil testing and nutrient management. Furthermore, the development and implementation of best management practices (BMPs) are critical in reducing the levels of agricultural pollution. Such measures are essential for mitigating the negative impacts on ecosystems and public health. Therefore, the adoption of preventive strategies aimed at minimizing pollution and its associated risks is highly recommended to ensure long-term environmental sustainability and human well-being.

Occurrence of polycyclic aromatic hydrocarbons in the Yellow River delta: Sources, ecological risks, and microbial response

This research investigated the distribution, sources, and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in the Yellow River Delta (YRD), China, emphasizing the response of soil microorganisms. The study involved quantitative analyses of 16 PAHs specified by the U.S. Environmental Protection Agency (USEPA) in both water and soil, utilizing metagenomic technique to determine the response of microbial communities and metabolism within the soil. Results noted that PAHs in the water mainly originate from pyrogenic source and in the soil originate from mixture source, with higher concentrations found in wetland areas compared to river regions. The ecological risk assessment revealed low-to-moderate risk. Microbial analysis demonstrated increased diversity and abundance of bacteria associated with PAHs in areas with higher PAHs pollution. Metagenomic insights revealed significant effects of organic carbon on PAHs degradation genes (ko00624 and ko00626), as well as significant differences in specific metabolic pathways including phenanthrene degradation, with key enzymes showing significant differences between the two environments. The study underscores the importance of understanding PAHs distribution and microbial responses to effectively manage and mitigate pollution in estuarine environments.

Deciphering Indigenous Bacterial Diversity of Co-Polluted Sites to Unravel Its Bioremediation Potential: A Metagenomic Approach

Polluted drains across the globe are affected due to reckless disposal of untreated industrial effluents resulting in significant water pollution affecting microbial community structure/dynamics. To elucidate this, polluted samples were collected from Budha Nala (BN) drain, Tung Dhab (TD) drain, and wastewater treatment plant (WWTP) receiving an inflow of organic pollutants as well as heavy metals due to anthropogenic activities. The sample of unpolluted pristine soil (PS) was used as control, as there is no history of usage of organic chemicals at this site. The bacterial diversity of these samples was sequenced using the Illumina MiSeq platform by amplifying the V3/V4 region of 16S rRNA. The majority of operational taxonomic unit (OTUs) at polluted sites belonged to phyla Proteobacteria specifically Gammaproteobacteria class, followed by Actinobacteria, Bacteriodetes, Chloroflexi, Firmicutes, Planctomycetes, WS6, and TM7, whereas unpolluted site revealed the prevalence of Proteobacteria followed by Actinobacteria, Planctomycetes, Firmicutes, Acidobacteria, Chloroflexi, Bacteroidetes, Verrucomicrobia, and Nitrospirae. The data sets decode unclassified species of the phyla Proteobacteria, Bacteriodetes, Chloroflexi, Firmicutes, and WS6, along with some unclassified bacterial species. The study provided a comparative study of changed microbial community structure, their possible functions across diverse geographical locations, and identifying specific bacterial genera as pollution bio-indicators of aged polluted drains.

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.