Biostimulation of Rhodovulum sp., for enhanced degradation of di-n-butyl phthalate under optimum conditions

Screening, identification, metabolic pathway of di-n-butyl phthalate degrading Priestia megaterium P-7 isolated from long-term film mulched cotton field soil in Xinjiang

Introduction

Di-n-butyl phthalate (DBP) is one of the most widely used phthalate esters (PAEs) and is considered an emerging global pollutant. It may pose a significant threat to ecosystem and human health due to its residual hazards and accumulation in the environment. Bacteria-driven PAE biodegradation is considered an economical and effective strategy for remediating such polluted environments.

Methods

A DBP-degrading bacterium (P-7), was isolated from long-term film mulched cotton field soil. Its identity was confirmed via physiological, biochemical, and 16S rRNA gene analyses. The degradation conditions were optimized through single-factor experiments and response surface methodology (RSM).Furthermore, the whole-genome sequencing coupled with metabolomics was employed to elucidate metabolic mechanisms.

Results

Priestia megaterium P-7 (P. megaterium P-7) achieved 100% DBP removal within 20 h under optimal conditions and exhibited broad substrate specificity for other PAEs. Genomic analysis identified key genes (lip, aes, ybfF, estA, and yvaK) encoding esterases/hydrolases that initiate DBP catabolism, converting it to phthalic acid (PA). Subsequent decarboxylation (pdc, bsdCD, mdcACDH, and lysA) and dioxygenase-mediated steps integrated PA into the TCA cycle. Metabolomics revealed three degradation pathways: decarboxylation (DBP → MBP → BB → BA→Catechol), hydrolysis (DBP → MBP → PA → PCA → Catechol) and direct β-oxidation (DBP → DEP → MEP → PA → Catechol).

Conclusion

P. megaterium P-7 demonstrates exceptional degradation efficiency, substrate versatility, and environmental stress tolerance, making it a promising candidate for bioremediation of organic pollutants in contaminated soil.

Harnessing landfill-derived Bacillus subtilis (LLS-04) for bio-electrodegradation of di-butyl phthalate: Comprehensive toxicity assessment across multiple biological models

Di-butyl phthalate (DBP), a pervasive environmental contaminant, poses significant ecological and health risks due to its persistence and toxicity. This study investigates the potential of a landfill-derived Bacillus subtilis strain (LLS-04) in bio-electrodegradation of DBP, alongside a comprehensive toxicity assessment across multiple biological models. Bio-electrodegradation efficiency was compared to biodegradation and electrodegradation, revealing that bio-electrodegradation achieved a remarkable 98.57 % reduction in DBP concentration significantly outperforming the other methods. This enhanced degradation was attributed to improved microbial activity and enzyme production, as indicated by higher protein content and increased esterase and dehydrogenase activities in the bio-electrodegradation system. The optimized conditions facilitated efficient degradation, with HPLC-MS/MS analysis confirming the breakdown of DBP into non-toxic end products via a proposed metabolic pathway. A comprehensive toxicity assessment, including in-silico analysis, in-vitro cytotoxicity and brine shrimp lethality assays, demonstrated a significant reduction in toxicity of BES treated effluent compared to DBP untreated effluent. Furthermore, in-vivo toxicity studies using animal model supported these findings, demonstrating reduced toxicity in the BES treated effluent compared to the DBP untreated effluent. Overall, these findings highlight the potential application of bio-electrodegradation in bioremediation strategies for phthalate pollution, offering an effective solution for reducing both DBP concentration and its environmental toxicity.

Phthalates in the environment of China: A scoping review of distribution, anthropogenic impact, and degradation based on meta-analysis

Phthalates (PAEs) are a group of endocrine-disrupting environmental chemicals (EEDs) that pose significant risks to human health. PAEs are widespread in various environmental media, including air, dust, water, and soil, and are subject to both horizontal and vertical migration. Human activities significantly influence the distribution of PAEs, yet current research on this relationship remains limited. In this study, we first describe the hot issues of PAEs in the environment through bibliometrics, and then review published related studies. We outline the global distribution of PAEs in different media and conducted a comparative analysis of their composition. Principal component analysis (PCA) revealed PAEs differences in environmental mediums and geographic locations. Correlation analysis between PAEs composition and human activities in China further demonstrated that PAE concentrations were closely linked to agricultural and industrial activities. We also discussed the biodegradation and abiotic degradation of PAEs, finding that bacteria play a crucial role in their degradation in soil. This study aims to assess the distribution, transfer, impact, and degradation of PAEs, providing insights for the prevention and remediation of PAE pollution.

Innovative Microbial Immobilization Strategy for Di-n-Butyl Phthalate Biodegradation Using Biochar-Calcium Alginate-Waterborne Polyurethane Composites

Di-n-butyl phthalate (DBP) is a prevalent phthalate ester widely used as a plasticizer, leading to its widespread presence in various environmental matrices. This study presents an innovative microbial immobilization strategy utilizing biochar, calcium alginate (alginate-Ca, (C12H14CaO12)n), and waterborne polyurethane (WPU) composites to enhance the biodegradation efficiency of DBP. The results revealed that rice husk biochar, pyrolyzed at 300 °C, exhibits relatively safer and more stable physical and chemical properties, making it an effective immobilization matrix. Additionally, the optimal cultural conditions for Bacillus aquimaris in DBP biodegradation were identified as incubation at 30 °C and pH 7, with the supplementation of 0.15 g of yeast extract, 0.0625 g of glucose, and 1 CMC of Triton X-100. Algal biotoxicity results indicated a significant decrease in biotoxicity, as evidenced by an increase in chlorophyll a content in Chlorella vulgaris following DBP removal from the culture medium. Finally, microbial community analysis demonstrated that encapsulating B. aquimaris within alginate-Ca and WPU layers not only enhanced DBP degradation, but also prevented ecological competition from indigenous microorganisms. This novel approach showcases the potential of agricultural waste utilization and microbial immobilization techniques for the remediation of DBP-contaminated environments.

Current strategies on bioremediation of personal care products and detergents: Sustainability and life cycle assessment

The increased use of personal care products and detergents in modern society has raised concerns about their potential adverse effects on the environment. These products contain various chemical compounds that can persist in water bodies, leading to water pollution and ecological disturbances. Bioremediation has emerged as a promising approach to address these challenges, utilizing the natural capabilities of microorganisms to degrade or remove these contaminants. This review examines the current strategies employed in the bioremediation of personal care products and detergents, with a specific focus on their sustainability and environmental impact. This bioremediation is essential for environmental rejuvenation, as it uses living organisms to detergents and other daily used products. Its distinctiveness stems from sustainable, nature-centric ways that provide eco-friendly solutions for pollution eradication and nurturing a healthy planet, all while avoiding copying. Explores the use of microbial consortia, enzyme-based treatments, and novel biotechnological approaches in the context of environmental remediation. Additionally, the ecological implications and long-term sustainability of these strategies are assessed. Understanding the strengths and limitations of these bioremediation techniques is essential for developing effective and environmentally friendly solutions to mitigate the impact of personal care products and detergents on ecosystems.

Insights into molecular mechanism of plasticizer biodegradation in Dietzia kunjamensis IITR165 and Brucella intermedia IITR166 isolated from a solid waste dumpsite

AIMS

Isolation of phthalate esters (PAEs) degrading bacteria from a solid waste dumpsite could degrade many plasticizers efficiently and to investigate their degrading kinetics, pathways, and genes.

METHODS AND RESULTS

Based on their 16S rRNA gene sequence the strains were identified as Dietzia kunjamensis IITR165 and Brucella intermedia IITR166, which showed a first-order degradation kinetic model under lab conditions. The quantification of phthalates and their intermediate metabolites identification were done by using ultra-high-performance liquid chromatography (UHPLC) and gas chromatography-tandem mass-spectrometry (GC-MS/MS), respectively. Both the bacteria utilized >99% dibutyl phthalate at a high concentration of 100-400 mg L-1 within 192 h as monitored by UHPLC. GC-MS/MS revealed the presence of metabolites dimethyl phthalate (DMP), phthalic acid (PA), and benzoic acid (BA) during DBP degradation by IITR165 while monobutyl phthalate (MBP) and PA were identified in IITR166. Phthalate esters degrading gene cluster in IITR165 comprised two novel genes coding for carboxylesterase (dkca1) and mono-alkyl phthalate hydrolase (maph), having only 37.47% and 47.74% homology, respectively, with reported phthalate degradation genes, along with the terephthalate dioxygenase system (tphA1, A2, A3, and B). However, IITR166 harbored different gene clusters comprising di-alkyl phthalate hydrolase (dph_bi), and phthalate dioxygenase (ophA, B, and C) genes.

CONCLUSIONS

Two novel bacterial strains, Dietzia kunjamensis IITR165 and Brucella intermedia IITR166, were isolated and found to efficiently degrade DBP at high concentrations. The degradation followed first-order kinetics, and both strains exhibited a removal efficiency of over 99%. Metabolite analysis revealed that both bacteria utilized de-methylation, de-esterification, and decarboxylation steps during degradation.

Phthalate esters: occurrence, toxicity, bioremediation, and advanced oxidation processes

Phthalic acid esters are emerging pollutants, commonly used as plasticizers that are categorized as hazardous endocrine-disrupting chemicals (EDCs). A rise in anthropogenic activities leads to an increase in phthalate concentration in the environment which leads to various adverse environmental effects and health issues in humans and other aquatic organisms. This paper gives an overview of the research related to phthalate ester contamination and degradation methods by conducting a bibliometric analysis with VOS Viewer. Ecotoxicity analysis requires an understanding of the current status of phthalate pollution, health impacts, exposure routes, and their sources. This review covers five toxic phthalates, occurrences in the aquatic environment, toxicity studies, biodegradation studies, and degradation pathways. It highlights the various advanced oxidation processes like photocatalysis, Fenton processes, ozonation, sonolysis, and modified AOPs used for phthalate removal from the environment.

Remediation of phthalate acid esters from contaminated environment—Insights on the bioremedial approaches and future perspectives

Phthalates are well-known emerging pollutants that are toxic to the environment and human health. Phthalates are lipophilic chemicals used as plasticizers in many of the items for improving their material properties. These compounds are not chemically bound and are released to the surroundings directly. Phthalate acid esters (PAEs) are endocrine disruptors and can interfere with hormones, which can cause issues with development and reproduction, thus there is a huge concern over their existence in various ecological surroundings. The purpose of this review is to explore the occurrence, fate, and concentration of phthalates in various environmental matrices. This article also covers the phthalate degradation process, mechanism, and outcomes. Besides the conventional treatment technology, the paper also aims at the recent advancements in various physical, chemical, and biological approaches developed for phthalate degradation. In this paper, a special focus has been given on the diverse microbial entities and their bioremedial mechanisms executes the PAEs removal. Critically, the analyses method for determining intermediate products generated during phthalate biotransformation have been discussed. Concluisvely, the challenges, limitations, knowledge gaps and future opportunities of bioremediation and their significant role in ecology have also been highlighted.

Electrochemical degradation performance and mechanism of dibutyl phthalate with hydrophobic PbO2 electrode

A polytetrafluoroethylene (PTFE) doped PbO₂ anode with a highly hydrophobicity was fabricated by electrodeposition method. In this process, vertically aligned TiO₂ nanotubes (TiO₂NTs) are formed by the anodic oxidation of Ti plates as an intermediate layer for PbO₂ electrodeposition. The characterization of the electrodes indicated that PTFE was successfully introduced to the electrode surface, the TiO₂NTs were completely covered with β-PbO₂ particles and gave it a large surface area, which also limited the growth of its crystal particles. Compared with the conventional Ti/PbO₂ and Ti/TiO₂NTs/PbO₂ electrode, the Ti/TiO₂NTs/PbO₂-PTFE electrode has enhanced surface hydrophobicity, higher oxygen evolution potential, lower electrochemical impedance, with more active sites, and generate more hydroxyl radicals (·OH), which were enhanced by the addition of PTFE nanoparticles. The electrocatalytic performance of the three electrodes were investigated using dibutyl phthalate (DBP) as the model pollutant. The efficiency of the DBP removal of the three electrodes was in the order: Ti/TiO₂NTs/PbO₂-PTFE > Ti/TiO₂NTs/PbO₂ > Ti/PbO₂. The degradation process followed the pseudo-first-order kinetic model well, with rate constants of 0.1326, 0.1266, and 0.1041 h^-1 for the three electrodes, respectively. The lowest energy consumption (6.1 kWh g^-1) was obtained after 8 h of DBP treatment using Ti/TiO₂NTs/PbO₂-PTFE compared to Ti/TiO₂NTs/PbO₂ (6.7 kWh g^-1) and Ti/PbO₂ (7.4 kWh g^-1) electrodes. Moreover, the effects of current density, initial pH and electrolyte concentration were investigated. Finally, the products of the DBP degradation process were verified based on gas chromatography-mass spectrometry analysis, and possible degradation pathways were described.

Environmental persistence, detection, and mitigation of endocrine disrupting contaminants in wastewater treatment plants – a review with a focus on tertiary treatment technologies

Endocrine disrupting chemicals are a group of contaminants that have severe effects on humans and animals when exposed, like cancer and alterations to the nervous and reproductive systems.

Insights into the bacterial community composition of farmed Caulerpa lentillifera: A comparison between contrasting health states

The bacterial communities of Caulerpa lentillifera were studied during an outbreak of an unknown disease in a sea grape farm from Vietnam. Clear differences between healthy and diseased cases were observed at the order, genus, and Operational Taxonomic Unit (OTU) level. A richer diversity was detected in the diseased thalli of C. lentillifera, as well as the dominance of the orders Flavobacteriales (phylum Bacteroidetes) and Phycisphaerales (Planctomycetes). Aquibacter, Winogradskyella, and other OTUs of the family Flavobacteriaceae were hypothesized as detrimental bacteria, this family comprises some well-known seaweed pathogens. Phycisphaera together with other Planctomycetes and Woeseia were probably saprophytes of C. lentillifera. The Rhodobacteraceae and Rhodovulum dominated the bacterial community composition of healthy C. lentillifera. The likely beneficial role of Bradyrhizobium, Paracoccus, and Brevundimonas strains on nutrient cycling and phytohormone production was discussed. The bleaching of diseased C. lentillifera might not only be associated with pathogens but also with an oxidative response. This study offers pioneering insights on the co-occurrence of C. lentillifera-attached bacteria, potential detrimental or beneficial microbes, and a baseline for understanding the C. lentillifera holobiont. Further applied and basic research is urgently needed on C. lentillifera microbiome, shotgun metagenomic, metatranscriptomic, and metabolomic studies as well as bioactivity assays are recommended.

Phthalic acid esters degradation by a novel marine bacterial strain Mycolicibacterium phocaicum RL-HY01: Characterization, metabolic pathway and bioaugmentation

Phthalic acid esters (PAEs) are one of the most widely used plasticizers and the well-studied environmental pollutants with endocrine disrupting properties. Investigation about PAEs in terrestrial ecosystem has been extensively conducted while the fate of PAEs in marine environment remains underexplored. In this study, a novel di-(2-ethylhexyl) phthalate (DEHP) degrading marine bacterial strain, Mycolicibacterium phocaicum RL-HY01, was isolated and characterized from intertidal sediments. Strain RL-HY01 could utilize a range of PAE plasticizers as sole carbon source for growth. The effects of different environmental factors on the degradation of PAEs were evaluated and the results indicated that strain RL-HY01 could efficiently degrade PAEs under a wide range of pH (5.0 to 9.0), temperature (20 °C to 40 °C) and salinity (below 10%). Specifically, when Tween-80 was added as solubilizing agent, strain RL-HY01 could rapidly degrade DEHP and achieve complete degradation of DEHP (50 mg/L) in 48 h. The kinetics of DEHP degradation by RL-HY01 were well fitted with the modified Gompertz model. The metabolic intermediates of DEHP by strain RL-HY01 were identified by ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis and then the metabolic pathway of DEHP was deduced. DEHP was transformed into di-ethyl phthalate (DEP) via β-oxidation and then DEP was hydrolyzed into phthalic acid (PA) by de-esterification. PA was further transformed into gentisate via salicylic acid and further utilized for cell growth. Bioaugmentation of strain RL-HY01 with marine samples was performed to evaluate its application potential and the results suggested that strain RL-HY01 could accelerate the elimination of DEHP in marine samples. The results have advanced our understanding of the fate of PAEs in marine ecosystem and identified an efficient bioremediation strategy for PAEs-polluted marine sites.