Biodegradation

Pharmaceutical residues are increasingly detected in freshwater systems at concentrations ranging from g/L to /L, raising concerns due to their persistence, bioactivity, and potential ecological and human health impacts. Conventional wastewater treatment plants typically achieve limited removal efficiencies (often 30–60

Heavy metal (HM) contamination represents a persistent global threat, demanding bioremediation strategies that are both mechanistically robust and ecologically sustainable. This review provides a next-generation perspective on vermiremediation by integrating species-level physiology, gut microbiome functionality, molecular detoxification pathways, synthetic biology innovations, multi-omics insights, and artificial intelligence (AI)-driven modeling into a unified framework. A central novelty of this work lies in the detailed elucidation of earthworm-microbe consortia and their synergistic contributions to metal sequestration, transformation, and detoxification-moving beyond traditional organism-centric views toward eco-engineered host-symbiont systems. We synthesize species-specific bioaccumulation patterns, toxicological responses, and detoxification mechanisms, supported by enrichment kinetic models. At the molecular scale, we highlight antioxidant defense pathways involving catalase, glutathione-S-transferase, and superoxide dismutase, alongside oxidative stress signaling, macromolecular damage, and thresholds that differentiate adaptive resilience from system failure. Advancements in synthetic biology includes gene editing, pathway reconstruction, and designer symbiotic microbes which are examined as emerging tools to enhance gut microbial functionality and engineer targeted metal-binding pathways. Multi-omics approaches provide a systems-level view of detoxification networks, revealing previously uncharacterized genes, enzymes, and metabolic signatures associated with HM tolerance and early biomarkers of sub-lethal stress. The incorporation of AI-based models introduces a data-driven dimension, enabling accurate prediction of remediation outcomes and optimization of vermiremediation strategies. Overall, this review advances vermiremediation from an empirical practice to a programmable, systems-biotechnology platform for sustainable HM bioremediation.

The environmental persistence of carbofuran, a potent methylcarbamate neurotoxin, necessitates the development of advanced biotechnological strategies to safeguard soil biodiversity. This study investigated the bioremediation potential of Bacillus paralicheniformis PPH2, a specialized symbiont isolated from a unique ecological niche, the gastrointestinal tract of the indigenous paddy field earthworm Glyphidrilus sp. Unlike traditional soil isolates, strain PPH2 exhibited superior metabolic resilience, growing on carbofuran as the sole carbon and energy source. Through Central Composite Design coupled with Response Surface Methodology, catabolic efficiency was optimized at pH 7.1, 34.7 °C, and 100 rpm, resulting in a validated degradation efficiency of 62.07 ± 1.12

In this study, a bacterial strain of Micrococcus yunnanensis was isolated from the discharge water of an organized industrial zone wastewater treatment plant and used in the bioremoval of Al, Ni, and As. The effects of different experimental conditions such as initial metal concentration, pH, temperature, contact time, and biomass concentration on metal bioremoval were evaluated, and peak removal conditions were identified. The highest removal rates were 80, 68, and 27.33

Acid mine drainage (AMD) is characterized by persistent acidity, high sulfate and dissolved metal concentrations. Sulfate-reducing bacteria (SRB) are attractive candidates for AMD remediation because dissimilatory sulfate reduction generates alkalinity while producing sulfide that can facilitate metal removal through precipitation. Extending these processes to acidic conditions has increased interest in acidophilic and acid-tolerant SRB (aSRB and atSRB), yet evidence from cultivation, molecular surveys and treatment systems has often been interpreted separately. This systematic review synthesized 53 culture-dependent, culture-independent, and treatment system studies from 2014 to 2024 to examine relationships among taxonomic occurrence, physiological capability, demonstrated low-pH sulfate reduction and treatment performance. Phylogenetic analysis showed that low-pH sulfate-reducing phenotypes were distributed across multiple lineages and 16S rRNA relatedness alone did not predict acid tolerance. Desulfosporosinus was the most consistently represented genus across studies, although its recurrence was influenced by cultivation strategies. Sulfate reduction was demonstrated below pH 3, with sustained low-pH activity most strongly supported by controlled reactor studies; approximately pH 4.0–5.5 emerged as a comparatively well-supported range, while activity at lower pH was more dependent on microbial physiology and experimental conditions. Low-pH sulfate reduction also emerged as a community-level process shaped by electron-donor use, metabolite turnover and complementary microbial functions, while treatment performance additionally depended on biomass retention, hydraulic conditions and sulfide management. The reviewed studies support a distinction between taxonomic presence, demonstrated activity and treatment contribution. Future work should prioritize standardized reporting of active sulfate-reduction conditions, stronger taxon-function validation and long-term field testing of low-pH sulfidogenic systems.

Cadmium (Cd) behavior in alkaline soils is primarily controlled by the interplay of solution complexation, anion- mediated transformation, and solid-phase interactions. The experiment included a series of integrated analyses to monitor Cd speciation, mobility, transformation, leaching, and fate in maize plants. Soil solution chemistry, bioavailability, and leachate-mediated Cd release kinetics were monitored alongside maize growth, yield, and Cd accumulation patterns, as well as associated health risks. In the present work, we examined Cd fate under five potassium-sourced (@200 mg kg−1 K) fertilizers (K-0-Control, KCl, K2SO4, K2HPO4, K2SiO3) with and without 1

The leather industry impacts the environment through the use of hazardous chemicals for dehairing and the improper disposal of waste from these processes. In this study, a newly isolated Bacillus altitudinis VK-1120 was utilized for hair waste valorization and keratinase production. The keratinase production was optimized, and the maximum activity of 220.82 U/mL was achieved at 40 °C, pH 8.0, and 100 rpm after 48 h. The activity of purified enzyme was inhibited by PMSF and EDTA, suggesting that the enzyme functions as a serine-metalloprotease. SDS-PAGE results revealed a molecular weight of 25 kDa for the purified keratinase. The optimum temperature and pH for the purified keratinase were 50 °C and 9.0, respectively. The keratinase solution was applied to the dehairing of goatskins using the industrial drum-based method, and complete dehairing was observed within 5 h. The enzymatic treatment significantly improved the waste liquor quality, reducing Biochemical Oxygen Demand (BOD) by 38.67

Poultry slaughterhouse residues, rich in organic matter (proteins and fats), represent an excellent substrate for biogas production through anaerobic digestion. This study aimed to evaluate the performance and stability of thermophilic mono-digestion of poultry slaughterhouse waste (PSW) and its co-digestion with the organic fraction of municipal solid waste (OFMSW), and to assess methane production kinetics under pilot-scale conditions. Experiments were performed in a 50 L pilot-scale digester operated at 55 °C for 41 days. Mono-digestion of PSW was conducted at a substrate-to-inoculum (S/I₁) ratio of 1:2 (VS basis), whereas co-digestion of PSW and OFMSW was performed at a substrate-to-inoculum (S/I₂) ratio of 1:3 (VS basis). The mono-digestion of PSW produced 1443 NL kg−1 VS of biogas and 916 NL CH₄ kg−1 VS of biomethane. Co-digestion of PSW and OFMSW generated 1134 NL kg−1 VS of biogas and 649 NL CH₄ kg−1 VS of biomethane, corresponding to an approximately 25

Biodegradation of aviation fuels remains a critical factor during storage and operation, affecting both the composition and performance properties of kerosene fractions. This study aims to establish the relationship between the component composition of modern jet fuels and their biostability. In addition, the effect of typical additives was evaluated. Four industrially used kerosene fractions differing in refining depth were investigated—straight-run, hydrodemercaptanized, hydrotreated, and hydrocracked—along with their mixtures containing antioxidant (Agidol-1) and lubricity additive (Unicor J). Biological tests were conducted under standardized conditions (IP 385/ASTM D6974; GOST 9.023) using Amorphotheca resinae as the test organism; changes in group hydrocarbon composition were analyzed by GC × GC–MS. It was found that susceptibility to biodegradation decreases with increasing refining depth, while microbial activity consistently resulted in a reduction in paraffinic and naphthenic hydrocarbons and a relative increase in aromatics; simultaneously, sulfur content decreases. Paradoxically, the most pronounced increases in acidity and existent gum content were observed in the hydrotreated and hydrocracked fractions. Agidol-1 exhibited biostatic (antimicrobial) activity, but was accompanied by a marked drop in aqueous phase pH (≈ 4), suggesting increased corrosion risk associated with the aqueous phase. Unicor J produced a slight positive effect, likely due to its surface-active properties.

To address the water–oil–cell interfacial mass-transfer barrier limiting microbial degradation of heavy crude oil, this study evaluated a biosurfactant–nonionic mixed-micelle strategy that integrates interfacial performance with microbial compatibility. Four binary surfactant systems were screened using the petroleum hydrocarbon-degrading consortium B10. Among them, the rhamnolipid/Triton X-100 formulation, designated RT, showed the best overall balance of mixed-micelle synergy, crude-oil solubilization, microbial growth compatibility, and apparent hydrocarbon attenuation. After 7 d, RT achieved an apparent attenuation efficiency of 60.0

Though biodegradable plastics have been widely developed as sustainable alternatives to petroleum-based plastics, their degradation behavior and microbial interactions in composting environments remain insufficiently understood. In this study, the degradation characteristics of polyhydroxybutyrate (PHB), polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), and polybutylene succinate (PBS), and the interactions between bacterial communities and functional genes, were evaluated in a 41-day aerobic composting system using anaerobically digested sewage sludge as substrate. Composting parameters were similarly affected by all biodegradable plastics, and the final compost reached a Solvita compost maturity index of 8.0 with no detectable pathogenic bacteria and a CO2 index of 7.83, indicating stable composting. After 41 days of composting, microcracks and microbial attachment were observed on all biodegradable plastic surfaces, with PHB and PBAT showing the most pronounced structural damage and biofilm formation, whereas microbial attachment to PLA was limited. Although biodegradable plastic addition did not greatly alter the overall bacterial community structure, it selectively promoted specific bacterial genera (Symbiobacterium, Paenibacillus, and Psychrobacillus). PICRUSt2-based functional gene prediction revealed that PHB degradation-related genes exhibited the highest predicted abundance, whereas PLA- and PBS-related genes showed low abundance, indicating differences in functional degradation potential among plastic types. Positive correlations among esterase- and hydrolase-related genes under biodegradable plastic-amended conditions suggest that coordinated microbial functional responses to biodegradable plastic addition. Network analysis further indicated that biodegradable plastic addition influenced interactions between specific bacterial genera and degradation-related functional genes. Overall, this study provides insights into bacterial functional adaptation during biodegradable plastic degradation under aerobic composting conditions.

Polystyrene (PS), a petroleum-based synthetic polymer which is extensively used in packaging, insulation, and consumer goods, has emerged as a major environmental pollutant. This report provides a comprehensive overview of recent advances in biological and synthetic biology strategies for novel PS-degrading microorganisms, including bacteria and fungi isolated from unique ecosystems such as insect gut microbiomes and extreme environments. Insects like mealworms and superworms have demonstrated the ability to ingest and degrade PS through symbiotic microbial activity, while fungi such as Aspergillus tubingensis and marine-derived fungi contribute enzymatically to polymer breakdown. Advances in enzymology involving oxidative enzymes like laccases and peroxidases have improved our understanding of PS degradation at the molecular level, supported by innovations in enzyme engineering and immobilization. The paper also examines the biodegradation abilities of bacteria, fungi, and microbes associated with insects and critically analyzes the methods used for degradation assessments, differentiating between genuine biodegradation and mineralization versus surface oxidation, fragmentation, and reduction in polymer weight. Moreover, the advancements in synthetic biology, which include metabolic engineering and engineered microbial consortia, and the biological upcycling of PS intermediates to valuable products, are also covered in light of the circular economy approach.

The management of water hyacinth through conventional composting is constrained by prolonged processing times despite its potential for effective humification and heavy metal stabilization. This study addresses this limitation by exploring an integrated Rotary Drum Composting (RDC) and Vermicomposting (VC) approach to accelerate humification and enhance metal immobilization, offering a more efficient pathway for aquatic biomass valorisation. Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC–MS) analysis demonstrate that RDC + VC technology drives a synergistic and accelerated conversion of key organic precursors into humic compounds. The simultaneous addition of Eisenia produced the highest rate of organic matter decomposition (44.33

In this study, the influence of natural zeolite on sulfur-based denitrification was evaluated through batch assays and parallel up-flow packed-bed biofilters operated under autotrophic and mixotrophic conditions. Reactors containing elemental sulfur alone and sulfur co-packed with natural zeolite were operated at nitrogen loading rates ranging from 1.08 to 12.87 mg N L−1 h−1. During the mixotrophic stages, methanol was added as the organic carbon source to both up-flow packed-bed biofilters, one packed with elemental sulfur (S0) alone and the other with a mixture of S0 and natural zeolite, to achieve C/N ratios ranging from 0.9 to 2.85. In batch experiments, the addition of zeolite enhanced autotrophic denitrification kinetics, increasing specific nitrate removal rates from 27–32 to 31–39 mg NO3−-N g−1 VSS d−1, while significantly reducing nitrite accumulation. In continuous reactors, zeolite showed limited influence at moderate nitrogen loading rates (NLRs) but substantially improved reactor performance at higher NLRs, maintaining nitrate removal efficiencies up to 87.3

This study demonstrates that inoculation with the Enterococcus wangshanyuanii strain F4 in a germ-free black soldier fly larval (BSFL) system enhances sulfamethoxazole (SMX) degradation, larval growth, and substrate conversion. Following inoculation with strain F4, the net SMX degradation rate reached 37.08

Indoor volatile organic compounds (VOCs) require treatment technologies that remain effective at low concentrations and high airflow rates without generating persistent secondary waste. This structured narrative review evaluates VOC removal by microalgae and algal–bacterial consortia using an evidence hierarchy that distinguishes direct gas-phase studies, gas–liquid reactor studies, and aqueous mechanistic studies. Formaldehyde and benzene, toluene, ethylbenzene, and xylenes (BTEX) are identified as the principal indoor VOC targets, whereas studies on phenols, polycyclic aromatic hydrocarbons, and other aqueous organic contaminants are considered mainly as mechanistic evidence. Direct evidence at indoor-relevant gas-phase concentrations remains scarce, and removal efficiencies obtained from liquid batch cultures cannot be extrapolated to indoor air without considering gas–liquid partitioning, biomass loading, reactor configuration, airflow, and abiotic losses. Quantitative comparison is further limited by inconsistent units, inadequate controls, incomplete carbon balances, and insufficient data on energy demand, byproducts, long-term stability, and bioaerosol containment. Future studies should therefore report standardized performance indicators and verify mineralization through mass-balance or isotope-based approaches. Current evidence supports microalgal systems primarily as application-specific biological polishing processes rather than established replacements for conventional air-cleaning technologies.

The release of nitrate-rich effluents and pathogens from domestic and industrial sources into drinking water sources poses a significant environmental and public health challenge. The present study evaluates the multifunctional potential of the Gram-positive bacterium Bacillus pacificus (Accession No. PV206819) as a sustainable bioagent for nitrate remediation and antimicrobial risk reduction within a circular bioeconomy framework. The nitrate removal efficiency corresponds to 65.8

With increasing waste generation and environmental concerns in textiles, biodegradability is considered one of the most important waste management strategies. The biodegradability behavior of textile products made from virgin materials has been extensively studied. Although it is known that recycled textile products provide significant environmental benefits, whether these materials have created a change in terms of biodegradability is still a subject of interest. Biodegradation of woven fabrics made of virgin cotton (CO)/recycled cotton (r-CO) fibers, recycled polyester (r-PET)/r-CO fiber blends, 100

Idol immersion waste (IIW) generated during Indian festivals is an emerging source of aquatic pollution due to heavy metals released from gypsum-based idols and synthetic pigments. This study investigated laboratory-scale in-vessel composting as a circular strategy for detoxification and resource recovery of IIW. Six bioreactors containing food waste, garden waste, cow manure, biochar, and varying gypsum proportions were operated for 30 days. ICP-OES analysis identified elevated Cr, Cu, Hg, Ni, Pb, and Zn in idol-derived residues. Sequential extraction revealed progressive transformation of metals from labile fractions to stable oxidizable and residual forms, indicating effective immobilization. Near-complete stabilization of Pb, Ni, and Hg was achieved their bioavailable fractions and water-soluble concentrations declining below analytical detection limits (immobilization factor 82.8–97.4

Hexabromocyclododecanes (HBCDs), a class of persistent organic pollutants (POPs), have been extensively used as additive flame retardants in building materials, textiles, and electronic equipment for decades. Although HBCDs have been gradually banned from production and application, their continuous release from existing products is expected to persist for more than a century, resulting in long-term environmental concern. Recent studies indicate that regulatory measures have been effective in most regions, yet HBCD contamination remains severe in certain areas, e.g., e-waste recycling zones. The reported half-lives of HBCD biotransformation in environmental media range from several to over 100 days, which are affected by contamination levels, redox potential, pH, and hydrodynamic conditions. Organohalide-respiring bacteria (OHRB) constitute a critical functional group in environmental microbial communities for anaerobic degradation of HBCDs, while the enzymatic and genetic mechanisms remain poorly characterized. Biotransformation of HBCDs by microbial strains and their enzymes has been reported, including Pseudomonas aeruginosa HS9, Citrobacter sp. Y3, and Alcanivorax sp. SZ2-4 and the corresponding enzymes CYP168A1, HBCD-hd-1, DadAH, and DadBH. However, several critical questions remain insufficiently addressed, including the stepwise dehalogenation mechanisms of the implicated enzymes and the metabolism of debrominated intermediates. This review summarizes current knowledge on the environmental persistence of HBCDs, microbial community responses to HBCD stress, and microbial degradation of HBCDs. It also identifies major knowledge gaps for future researches, aiming to promote the bioremediation of HBCD contamination.