Earthworm Eisenia Fetida Research Articles

Enantioselective Oxidative Stress and DNA Damage Induced by Rac- and S-metolachlor on the Earthworm Eisenia fetida.

Metolachlor is a widely used chiral herbicide. However, information on its enantioselective toxicity to earthworms, an important soil organism, remains limited. Herein, the effects of Rac- and S-metolachlor on oxidative stress and DNA damage in Eisenia fetida were investigated and compared. Moreover, the degradation of both herbicides in the soil was also determined. The results showed that reactive oxygen species (ROS) in E. fetida were more easily induced by Rac-metolachlor than S-metolachlor at a higher concentration (above 16 µg/g). Similarly, the effects of Rac-metolachlor on superoxide dismutase (SOD) activity and DNA damage in E. fetida were more significant than those of S-metolachlor at the same exposure concentration and time. Rac- and S-metolachlor did not result in severe lipid peroxidation. The toxic effects of both herbicides on E. fetida gradually decreased after 7 days as the exposure was prolonged. At the same concentration, S-metolachlor degrades faster than Rac-metolachlor. These results suggest that Rac-metolachlor has a greater effect on E. fetida than S-metolachlor, providing a significant reference for the rational use of metolachlor.

Evaluation of Anthelmintic Activity and GC-MS Characterization of Urochloa distachya (L.)

Background: The helminthiasis parasitic worm present in the gastrointestinal tract of the animal cause infection and physiological damage. This occurs due to poor sanitation, impecunious personal hygiene, low socioeconomic position, and lack of education. Aim: Urochloa distachya (Poaceae) commonly called as signal grass and used as fodder for the animal. The present investigation was undertaken to investigate the phytochemicals and to study the anthelmintic activity. Materials and Methods: The plant material was extracted by using petroleum ether and methanol in Soxhlet apparatus and the obtained extract was subjected to GC-MS analysis for the identification of the bioactive components responsible for anthelmintic activity. The anthelmintic activity was performed against earthworms (Eisenia fetida) at concentrations 12.5, 25, and 50 mg/mL using piperazine citrate as standard. Results: The GC-MS analysis of the petroleum ether extract showed five major and ten minor compounds. The major compounds were identified as Stigmasterol (14.76%); α-Amyrin (12.47%); γ-Sitosterol (10.31%); 17-(1,5-Dimethyl-3-phen ylthiohex-4-enyl) -4,4,10,13,14-pentamethyl 2,3,4,5,6,7,10,11,12-(9.12%) and β-Amyrin (8.83%). The minor compounds were D:C-Friedo-B': A'-neogammacer-9(11)-ene, 3-methoxy-, (3β)-(8.28%); Tritetracontane (7.23%); Campesterol (4.68%); Phytol (4.05%); Cholesterol (3.39%); Hexadecanoic acid, methyl ester (2.20%); 2-Pyrrolidinone, 1-methyl-(1.46%); Oleic acid, 3-(octadecyloxy) propyl ester (1.27%); Squalene (0.84%) and 9,19-Cyclolanostane-3,7-diol (0.68%). The time taken for paralysis and death of Eisenia fetida parasite was noticed by methanolic and petroleum ether extract at a concentration of 50 mg/kg as compared to the standard drug. Conclusion: The anthelmintic activity of the plant was most achieved by methanolic extract which could be attributed to the presence of the Octadecanoic acid. Also, the anthelmintic active of the petroleum ether extract could be attributed to the antimicrobial, antibacterial, antifungal, and antiprotozoal activities of the Hexadecanoic acid, methyl ester; Phytol; Squalene; Cholesterol, and γ-Sitosterol.

Mechanistic insights into phenanthrene-triggered oxidative stress-associated neurotoxicity, genotoxicity, and behavioral disturbances toward the brandling worm (Eisenia fetida) brain: The need for an ecotoxicological evaluation

In this study, earthworm (Eisenia fetida) brain was chosen as targeted receptors to probe the mechanisms of oxidative stress-related neurotoxicity, genotoxicity, and behavioral disturbances triggered by PHE. Results showed that PHE stress can initiate significant amounts of ROS, thus triggering oxidative stress in E. fetida brain. These effects were accompanied by a significant increase of damage to macromolecules DNA and lipids, resulting in severe oxidative effects. PHE exposure can induce AChE inhibition by ROS-induced injury and the accumulation of excess ACh at the nicotinic post-synaptic membrane, thus inducing aggravated neurological dysfunction and neurotoxicity of E. fetida through an oxidative stress pathway. Moreover, the burrowing behavior of earthworms was disturbed by oxidative stress-induced neurotoxicity after exposure to PHE. Furthermore, the abnormal mRNA expression profiles of oxidative stress- and neurotoxicity-related genes in worm brain were induced by PHE stress. The IBR results suggested that E. fetida brain was suffered more serious damage caused by PHE under higher doses and long-term exposure. Taken together, PHE exposure can trigger oxidative stress-mediated neurotoxicity and genotoxicity in worm brain and behavioral disorder through ROS-induced damage. This study is of great significance to evaluate the harmful effects of PHE and its mechanisms on soil ecological health.

A green approach to copper biodetoxification and sustainable agriculture application by vermicomposting in pig manure

A green approach of copper (Cu) contaminated pig manure composting by earthworm Eisenia fetida was optimized. This work aims to assess the relationship between the bio-fertility properties and bioaccumulation of Cu during vermicomposting with five different doses of Cu. The optimal concentration of copper largely promoted the enrichment of nitrogen, phosphorus, and potassium, but the biological activities of earthworms could be inhibited once the Cu concentration exceed the threshold. When the Cu doses at 300 mg kg−1, the nutrient recovery rate (Irecovery) of available nitrogen, phosphorus and potassium reached their highest value, concomitant with largest C/N ratio reduced at 46.01 %. Moreover, nutrients recovery mechanism of total phosphorus increased up to 0.11 % h−1 and higher bioaccumulations in faces and intestine were detected by 1.79 and 0.99, respectively, during vermicomposting. The maximal enzyme activity rates (kmax) indicate that the enzyme activities, such as ROS and SOD, are sensitive bioindicators, which can be used to estimate the stress response of earthworms and Cu biotoxicity. The maximum specific growth rate (μmax) of the actinomycetes (TAct) increased gradually from 0.02 to 0.04 with the increase of Cu doses, but total fungi (TF) showed different response to μmax, which decreased firstly and then increased. It was demonstrated that Cu influenced the gut microbial community to vary the bio-fertility properties and bioaccumulation of Cu in the pig manure. All the findings refer that the vermicomposting could be the sustainable agricultural practices.

Impact of progressively cumulative exposure of AgNPs on earthworms (Eisenia fetida) and implication for eco-toxicological risk assessment

Hazardous pollutants released into the real environment mostly own long-lasting cumulative characteristics and have progressively negative impacts on organisms, which are always neglected in laboratory toxicological tests. Here in this study, the different ecotoxicity of Ag nanoparticles (AgNPs) on earthworm Eisenia fetida was compared via various endpoints and transcriptional sequencing between the 28-day progressively repeated (from 60 to 80, final 100 mg/kg) and one-step (directly to 100 mg/kg) exposure. The results showed that earthworms under progressively repeated exposure showed significantly less biomass loss and reproductive inhibition, as well as lower Ag bioaccumulation (15.6 mg/kg) compared with one-step exposure (17.9 mg/kg). The increases in enzyme activities (superoxide enzyme and catalase) and gene expression (metallothionein) also implied higher antioxidant and genetic toxicity in one-step exposed earthworms compared with those from progressively repeated exposure. Furthermore, the transcriptomic analysis identified 582 and 854 differentially expressed genes in the treatments of one-step and repeated exposure respectively compared with the control group. The results of pathway annotation and classification suggested similar enrichments of damage induction but different in toxic stress responses, whereas earthworms from repeated exposure possessed more detoxification-related pathways like translation and multicellular organismal processes. This study innovatively took into account the impacts of processive exposure occurring in the real environment and elucidated distinctions of toxicity and adaptation caused by different exposure patterns, which provided the theoretical basis for real risk identification under the framework and guidance of traditional toxicology, also the implication for the improvement of eco-toxicological risk assessment.

Conversion of Leather Industry Solid Waste to Organic Fertilizer by Vermicomposting: Use for Plant Growth

The generation of leather industry solid waste is a matter of concern for its potential polluting ability. This study assessed vermicomposting of leather industry-generated lime flesh and shaving waste through a mix with cattle dung using Eisenia fetida earthworm, aiming at sustainable reuse in agriculture. The chromium content of shaving waste was optimized to under 2 mg/kg using hydrogen peroxide with potassium carbonate treatment. The lime flesh was treated with hydrochloric acid treatment. Treated shaving waste and lime flesh were mixed with cattle dung in a proportion of 1:1 and 2:1 in different vermicompost fields. After 30 days 40 Eisenia fetida were introduced in each field and vermicomposted for 90 days within a moisture of 50%. The number of earthworms increased in the 1:1 portion of vermicompost. The number of earthworms, pH, total organic carbon (TOC), total Kjeldahl nitrogen (TKN), carbon and nitrogen ratio (C: N), total potassium (TK) and total phosphorus (TP) readings was taken at 0, 30, 60 and 90 days respectively. Composting resulted in a significant reduction of pH, and TOC. A reduction in C: N ratio by approximately nine-fold and an increase in TKN and TP was observed. A slight reduction of TK was also observed. The results indicated that the earthworm Eisenia fetida has been able to convert the lime flesh and shaving waste into nutrient-enriched fertilizer products in the same proportion of waste and cow dung. The vermicompost was applied on the Napier grass plantation and the accumulation of heavy metal effect on plants was investigated for eco-friendly plant growth. The composts and plants’ different parts were analysed for heavy metals. It was found to be under the permissible limits recommended by WHO. The vermicompost enhanced the organic matter significantly and nutrients were improved for better crop yield.

Oxidative stress and gene expression induced by biodegradable microplastics and imidacloprid in earthworms (Eisenia fetida) at environmentally relevant concentrations

The environmental issues caused by biodegradable microplastics (BMPs) from polylactic acid (PLA) as well as pesticides are of increasing concern nowadays. In this study, the toxicological effects of the single and combined exposure of PLA BMPs and imidacloprid (IMI), a neonicotinoid insecticide, on earthworms (Eisenia fetida) were investigated in terms of oxidative stress, DNA damage, and gene expression, respectively. The results showed that compared with the control, SOD, CAT and AChE activities in the single and combined treatments decreased significantly, and POD activity showed an “inhibition-activation” trend. SOD and CAT activities of combined treatments on day 28 and AChE activity of combined treatment on day 21 were significantly higher than those of the single treatments. For the rest of the exposure period, SOD, CAT and AChE activities in the combined treatments were lower than those in the single treatments. POD activity in the combined treatment was significantly lower than those of single treatments at day 7 and higher than that of single treatments at day 28. MDA content showed an “inhibition-activation-inhibition” trend, and the ROS level and 8-OHdG content increased significantly in both the single and combined treatments. This shows that both single and combined treatments led to oxidative stress and DNA damage. ANN and HSP70 were expressed abnormally, while the SOD and CAT mRNA expression changes were generally consistent with the corresponding enzyme activities. The integrated biomarker response (IBR) values were higher under combined exposures than single exposures at both biochemical and molecular levels, indicating that combined treatment exacerbated the toxicity. However, the IBR value of the combined treatment decreased consistently at the time axis. Overall, our results suggest that PLA BMPs and IMI induce oxidative stress and gene expression in earthworms at environmentally relevant concentrations, thereby increasing the risk of earthworms.

Oxidative potential of heavy-metal contaminated soil reflects its ecological risk on earthworm

The ecological risk of heavy metal-contaminated soil is usually evaluated by its oxidative stress on terrestrial animals, which are vulnerable to the impact of individual differences of animals and environmental conditions. Oxidative potential (OP) is the potential of particles to induce the formation of reactive oxygen species (ROS). In this study, OP of the in situ contaminated soils collected from an industrial site (i.e., 64.5–7783 mg/kg of Cu, 54.9–397 mg/kg of Pb, 278–2085 mg/kg of Zn and 0.615–121 mg/kg of Cd) were measured as 38.0–60.1 pmol/min/mg, and the water extractable Cu, Pb, Zn, and Cd in soils have been proved to contribute 89%–98% to OP. Oxidative stress in earthworms (Eisenia fetida) caused by the industrial contaminated soils can be reflected by the biomarkers such as 8-hydroxy-2′-deoxyguanosine, metallothionein, and antioxidant enzymes, and a negative correlation presents between the comprehensive biomarker response index and the OP of soils (r = −0.979, p < 0.01). This is the first time to propose a dose-response relationship between OP and oxidative stress. Metabolomic analysis also verified that the regulation of four ROS-related metabolites (i.e., l-pipecolate, 1-methylhistidine, 5-methoxytryptamine, and xanthosine) in earthworms treated with contaminated soil were directly correlated with OP values. These results indicate that OP can be used as an indicator for ecological risk assessment of heavy metal-contaminated soil, which provides a fast, stable and easily testable chemical method.

Ecotoxicological evaluation of oxidative stress-mediated neurotoxic effects, genetic toxicity, behavioral disorders, and the corresponding mechanisms induced by fluorene-contaminated soil targeted to earthworm (Eisenia fetida) brain

Fluorene is a commonly identified PAH pollutant in soil and exhibits various worrisome hazardous effects to soil organisms. Currently, the toxicity profiles of fluorene on earthworm brain are rare, and the mechanisms and their corresponding pathways involved in fluorene-triggered neurotoxicity, genotoxicity, and behavior changes have not been reported hitherto. Herein, earthworm (Eisenia fetida) brain was chosen as targeted receptor to explore the neurotoxic effects, genetic toxicity, behavioral disorders, and related mechanisms caused by fluorene-induced oxidative stress pathways. The results showed excess fluorene initiated the release of excessive quantities of ROS in earthworm brain, which have caused oxidative stress and accompanied by serious oxidative effects, including LPO (lipid peroxidation) and DNA injury. To minimize the damage effects, the antioxidant defense mechanisms (antioxidant enzymes and non-enzymatic antioxidants) were activated, and entailed a decrease of the antioxidant capacity in E. fetida brain, which, in turn, causes further ROS-induced ROS release. Exposure of fluorene induced the abnormal mRNA expression of genes relevant to oxidative stress (e.g., GST, SOD, CAT, GPx, MT, and Hsp70) and neurotoxicity (e.g., H02, C04, D06, and E08) in E. fetida brain. Specifically, fluorene can bind directly to AChE, destroying the conformation of this protein, and even affecting its physiological functions. This occurrence caused the inhibition of AChE activity and excess ACh accumulation at the nicotinic post-synaptic membrane, finally triggering neurotoxicity by activation of pathways related to oxidative stress. Moreover, the avoidance responses and burrowing behavior were obviously disturbed by oxidative stress-induced neurotoxicity after exposure to fluorene. The results form IBR suggested more severe poisoning effects to E. fetida brain initiated by high-dose and long-term exposure of fluorene. Among, oxidative stress injury and genotoxic potential are more sensitive endpoint than others. Collectively, fluorene stress can provoke potential neurotoxicity, genotoxicity, and behavioral disturbances targeted to E. fetida brain through the ROS-mediated pathways involving oxidative stress. These findings are of great significance to estimate the detrimental effects of fluorene and the corresponding mechanisms on soil eco-safety.

Significant contributions of biochar-derived dissolved matters to ecotoxicity to earthworms (Eisenia fetida) in soil with biochar amendment

Significant contributions of biochar-derived dissolved matters to ecotoxicity to earthworms (Eisenia fetida) in soil with biochar amendment

Vermitoxicity of aged biochar and exploring potential damage factors

Although biochar is a promising soil amendment, its characteristics change owing to its aging in soil. Studies have shown that some aged biochar is hazardous to plants and soil microbiota. Earthworms are well-known soil ecosystem engineers; nevertheless, the toxic effects of aged biochar on them (vermitoxicity) are yet unknown, and it is necessary to explore the potential risk factors. Here, a series of soil culture experiments were conducted to systematically examine the vermitoxicity of aged biochar at various levels utilizing the earthworm Eisenia fetida and corncob biochar.. Acute toxicity bioassays were also used to evaluate several potential harm factors utilizing modified aged biochar/leaching solutions. The findings showed that both fresh and aged biochar might have adverse effects on earthworms, and that aged biochar was more toxic than fresh biochar with LC50s reduced to 6.89%. Specifically, aged biochar caused earthworm death, growth inhibition with a maximum of 36.6%, and avoidance with 100% avoidance at the application rates of 2% at the individual-behavioral level. At the cellular and physiological-biochemical levels, aged biochar damaged coelomocyte lysosomal membrane stability, disrupted antioxidant enzyme activities, and improved the malondialdehyde (MDA) content in earthworms. Heat-treated and pH-modified aged biochar exhibited less acute toxicity on earthworms than aged biochar, whereas aqueous and acetone extracts showed weak vermitoxicity. As a result, earthworms may be harmed by volatile organic compounds (VOCs), an improper pH, and aqueous and acetone extracts. Additionally, the range of neural red retention times (NRRTs) was reviewed as ∼20–70 min mostly. This study, as far as we know, is the first to evaluate the vermitoxicity of aged biochar and its potential damage factors. The results may enhance our understanding of ecological toxicity of biochar, particularly over the long term, and lead to the development of application standards for biochar amendments to the soil.

Combined ecotoxicological effects of different-sized polyethylene microplastics and imidacloprid on the earthworms (Eisenia fetida)

Microplastics (MPs) and pesticides frequently coexist in farmland soil; however, there are relatively few studies on the ecological risk assessment of soil animals attributed to the combined pollution caused by MPs and pesticides. Moreover, the influence of particle size on the combined toxic effects of MPs and pesticides remains poorly understood. In this study, different-sized polyethylene MPs (PE MPs; 10 μm, 500 μm, and 2 mm) were combined with a series of imidacloprid concentrations (IMI; 0.10, 0.50 and 1.00 mg/kg), and earthworms (Eisenia fetida) were exposed to these MP and IMI combinations for 28 d to explore the combined toxic effects and mechanisms. The results showed, compared with IMI or PE MPs exposure alone, the combined exposure of IMI and PE MPs did not substantially increase the acute toxicity of earthworms but significantly inhibited weight increase and induced more serious epidermal damage to earthworms with a size effect; among these 10 μm PE MPs combined with IMI exhibited the strongest toxic effects. In addition, the combined exposure decreased antioxidant enzymes activity and caused oxidative damage in earthworms. Transcriptome results demonstrated most of the treatment combinations affected the ferroptosis pathway, which was further verified by the increase in the total iron content, reactive oxygen species, and malondialdehyde content in earthworms. Combined with the analysis of key signalling pathways, the above results revealed that the combined exposure to IMI and PE MPs showed stronger toxicity to earthworms than exposure to either IMI or MPs alone, which was mediated by the superimposed effect of ferroptosis and oxidative damage. Moreover, the effect was size-dependent, with 10 μm PE MPs combined with IMI exhibiting the strongest toxic effects. This study aimed to provide data to support the ecological risk assessment of soil animals caused by the combined pollution of MPs and coexisting pesticides.

Accumulation and speciation of arsenic in Eisenia fetida in sodium arsenite spiked soils - A dynamic interaction between soil and earthworms

Arsenic (As) is a toxic metalloid that is a significant global pollutant of the environment and a persistent bioaccumulation carcinogen. Earthworms are frequently employed as sentinel organisms to investigate the bioavailability of As in contaminated soils. However, the process of As accumulation in earthworms and the mechanism of transformation of As species in their bodies are not well understood. The accumulation of As and variation of As species in the earthworms (Eisenia fetida) exposed to sodium arsenite (0, 20, and 80 mg kg−1 As) were investigated in this study. The total As concentration of earthworms in the three treatments at various sample times was dose-dependent on soil As content. After 56 days of exposure, the high concentration treatment had the highest total As content (772 ± 21 mg kg−1) in earthworms, followed by the low concentration treatment (579 ± 42 mg kg−1) and control (31 ± 1 mg kg−1). During 56 days, the proportion of trivalent As in earthworms increased from 70% to more than 90%, while pentavalent As decreased by 11–18%. On day 28, the sum of the four organic As species reached a maximum (<1%). Changes in soil As species and an increase in bioavailable As cause earthworms to accumulate more As. The total As in soil after 56 days of exposure was 9.51 ± 0.50, 25.6 ± 0.60, and 82.8 ± 0.28 mg kg−1, which was not significantly different from the total As in soil before the experiment. These findings are useful in assessing the risk of earthworm exposure to sodium arsenite in the soil.

Rapid assessment of the toxic quality of sludge by analysing the behaviour of the earthworm Eisenia fetida

Dans un contexte d’anticipation du futur décret relatif aux critères de qualité agronomique et d’innocuité selon les conditions d’usage pour les matières fertilisantes et les supports de culture (MFSC), dit décret « socle commun MFSC », et dans le cadre d’un projet de renforcement de la valorisation agronomique de ses boues, la métropole de Lyon s’est engagée dans une étude pour qualifier rapidement les boues de deux de ses stations d’épuration. Pour chacun des sites concernés, 12 prélèvements ont été effectués puis analysés : paramètres physico-chimiques réglementaires et caractérisation écotoxique menée par ViewPoint. Les contraintes exigées pour le développement de cette nouvelle approche étaient d’obtenir une note discriminante, rapidement disponible après 24 à 48 heures après réception des échantillons en complément des tests classiques de laboratoire accessibles près de dix jours après le prélèvement, voire plus d’un mois pour certains « nouveaux » paramètres envisagés par le projet de décret sous le nom de « tests sentinelles ». ViewPoint a mis au point un protocole pour mesurer les réponses comportementales du ver Eisenia fetida en contact avec des boues d’épuration. La mesure consiste à placer dans une vingtaine de boîtes de Petri une moitié de zone avec un échantillon de boue diluée et d’y introduire un ver. Un système de vidéo-tracking mesure, pour chaque individu, différents traits comportementaux (vitesse, zone de préférence…) durant 25 minutes de lecture. Pour finir, cinq concentrations de boue sont testées pour chaque prélèvement. Un travail d’automatisation de la lecture et de traitement de la donnée a été effectué pour fournir une note à chaque échantillon. Cette méthode permet aujourd’hui de qualifier rapidement les boues d’épuration. Elle doit toutefois être consolidée avec des tests sur d’autres matrices. Il est prévu d’effectuer un travail complémentaire de corrélation de cette nouvelle méthodologie avec la norme relative à la mesure du taux de reproduction des vers.

Extreme environmental doses of diisobutyl phthalate exposure induce oxidative stress and DNA damage in earthworms (Eisenia fetida): Evidence at the biochemical and molecular levels

Diisobutyl phthalate (DIBP), as a plasticizer, is widely used and has caused many extreme soil contamination scenarios, posing potential risks to soil fauna. However, the toxic effects and mechanisms of DIBP on soil fauna remain unclear. In this study, earthworms (Eisenia fetida) were used as model animals to explore the subchronic toxicity of extreme DIBP soil exposure (300, 600, and 1200 mg/kg) for 28 days. The results showed that the level of reactive oxygen species (ROS) and the contents of malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) in E. fetida were significantly increased during continuous DIBP exposure. In addition, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were significantly inhibited while glutathione S-transferase (GST) activity was activated during continuous exposure. Integrated biological response (IBR) analysis showed that DIBP had positive dose-dependent toxicity and negative time-dependent toxicity to E. fetida, and SOD/CAT were selected as sensitive biomarkers. The molecular docking study found that DIBP could stably bind to SOD/CAT through hydrogen bonding, which further proved its sensitivity. This study provides primary data for ecological and environmental risk assessment of extreme dose DIBP soil pollution.

How do different arsenic species affect the joint toxicity of perfluorooctanoic acid and arsenic to earthworm Eisenia fetida: A multi-biomarker approach

Perfluorooctanoic acid (PFOA) and arsenic are widely distributed pollutants and can coexist in the environment. However, no study has been reported about the effects of different arsenic species on the joint toxicity of arsenic and PFOA to soil invertebrates. In this study, four arsenic species were selected, including arsenite (As(III)), arsenate (As(V)), monomethylarsonate (MMA), and dimethylarsinate (DMA). Earthworms Eisenia fetida were exposed to soils spiked with sublethal concentrations of PFOA, different arsenic species, and their binary mixtures for 56 days. The bioaccumulation and biotransformation of pollutants, as well as eight biomarkers in organisms, were assayed. The results indicated that the coexistence of PFOA and different arsenic species in soils could enhance the bioavailability of arsenic species while reducing the bioavailability of PFOA, and inhibit the arsenic biotransformation process in earthworms. Responses of most biomarkers in joint treatments of PFOA and As(III)/As(V) showed more significant variations compared with those in single treatments, indicating higher toxicity to the earthworms. The Integrated Biomarker Response (IBR) index was used to integrate the multi-biomarker responses, and the results also exhibited enhanced toxic effects in combined treatments of inorganic arsenic and PFOA. In comparison, both the biomarker variations and IBR values were lower in joint treatments of PFOA and MMA/DMA. Then the toxic interactions in the binary mixture systems were characterized by using a combined method of IBR and Effect Addition Index. The results revealed that the toxic interactions of the PFOA/arsenic mixture in earthworms depended on the different species of arsenic. The combined exposure of PFOA with inorganic arsenic led to a synergistic interaction, while that with organic arsenic resulted in an antagonistic response. Overall, this study provides new insights into the assessment of the joint toxicity of perfluoroalkyl substances and arsenic in soil ecosystems.

Microplastic pollution destabilized the osmoregulatory metabolism but did not affect intestinal microbial biodiversity of earthworms in soil

Metabolomic and gut microbial responses of soil fauna to environmentally relevant concentrations of microplastics indicate the potential molecular toxicity of microplastics; however, limited data exist on these responses. In this study, earthworms (Eisenia fetida) were exposed to spherical (25–30 μm diameter) polystyrene microplastic-contaminated soil (0.02%, w:w) for 14 days. Changes in weight, survival rate, intestinal microbiota and metabolic responses of the earthworms were assessed. The results showed that polystyrene microplastics did not influence the weight, survival rate, or biodiversity of the gut microbiota, but significantly decreased the relative abundance of Bacteroidetes at the phylum level. Moreover, polystyrene microplastics disturbed the osmoregulatory metabolism of earthworms, as indicated by the significantly decreased betaine, myo-inositol and lactate, and increased 2-hexyl-5-ethyl-furan-3-sulfonic acid at the metabolic level. This study provides important insights into the molecular toxicity of environmentally relevant concentrations of polystyrene microplastics on soil fauna.

Assessment of the Ecological Status of Soils Contaminated by the Copper Mining Industry in Chile: Earthworms to the Rescue

Soil fauna can serve as an excellent tool for ecological assessment of soil quality. The earthworm Eisenia fetida L. is widely used as a bioindicator organism to assess the toxicity of metals, metalloids, and other pollutants. Many studies have shown that the concentrations of metals and metalloids toxic to earthworms are an order of magnitude lower in artificially contaminated soils than in industrially contaminated soils. The novelty of this study is that toxicity estimates were made using native industrially contaminated soils. The results of the two experiments demonstrate the potential use of earthworms for ecological assessment of soils contaminated with metals and metalloids due to copper mining activities in central Chile. The main contaminant in these soils was copper, but arsenic, commonly found in copper ore, was also present in the contaminated soils. In the short-term bioassay, E. fetida earthworms avoided the soil in response to increasing copper content. However, in long-term experiments, arsenic proved to be more toxic to earthworm reproduction, while copper had little effect. In this study, we present toxicity thresholds for copper and arsenic to E. fetida in industrially contaminated native soils.

Co-composting of faecal sludge and carbon-rich wastes in the earthworm's synergistic cooperation system: Performance, global warming potential and key microbiome.

Composting is an effective alternative for recycling faecal sludge into organic fertilisers. A microflora-earthworm (Eisenia fetida) synergistic cooperation system was constructed to enhance the composting efficiency of faecal sludge. The impact of earthworms and carbon-rich wastes (rice straw (RS) and sawdust (S)) on compost properties, greenhouse gas emissions, and key microbial species of composting were evaluated. The addition of RS or S promoted earthworm growth and reproduction. The earthworm-based system reduced the volatile solid of the final substrate by 13.19-16.24 % and faecal Escherichia coli concentrations by 1.89-3.66 log10 cfu/g dry mass compared with the earthworm-free system. The earthworm-based system increased electrical conductivity by 0.322-1.402 mS/cm and reduced C/N by 56.16-64.73 %. The NH4+:NO3- ratio of the final faecal sludge and carbon-rich waste was <0.16. The seed germination index was higher than 80 %. These results indicate that earthworms contribute to faecal sludge maturation. Earthworm addition reduced CO2 production. The simultaneous addition of earthworms and RS system (FRS2) resulted in the lowest global warming potential (GWP). The microbial diversity increased significantly over time in the RS-only system, whereas it initially increased and later decreased in the FRS2 system. Cluster analysis revealed that earthworms had a more significant impact on the microbial community than the addition of carbon-rich waste. Co-occurrence networks for earthworm-based systems were simple than those for earthworm-free systems, but the major bacterial genera were more complicated. Highly abundant key species (norank_f_Chitinophagaceae and norank_f_Gemmatimonadaceae) are closely related. Microbes may be more cooperative than competitive, facilitating the conversion of carbon and nitrogen in earthworm-based systems. This work has demonstrated that using earthworms is an effective approach for promoting the efficiency of faecal sludge composting and reducing GWP.

Nanoplastics induce molecular toxicity in earthworm: Integrated multi-omics, morphological, and intestinal microorganism analyses.

The toxicity of nanoplastics (NPs) at relatively low concentrations to soil fauna at different organismal levels is poorly understood. We investigated the responses of earthworm (Eisenia fetida) to polystyrene NPs (90-110nm) contaminated soil at a relatively low concentration (0.02% w:w) based on multi-omics, morphological, and intestinal microorganism analyses. Results showed that NPs accumulated in earthworms' intestinal tissues. The NPs damaged earthworms' digestive and immune systems based on injuries of the intestinal epithelium and chloragogenous tissues (tissue level) and increased the number of changed genes in the digestive and immune systems (transcriptome level). The NPs reduced gut microorganisms' diversity (Shannon index) and species richness (Chao 1 index). Proteomic, transcriptome, and histopathological analyses showed that earthworms suffered from oxidative and inflammatory stresses. Moreover, NPs influenced the osmoregulatory metabolism of earthworms as NPs damaged intestinal epithelium (tissue level), increased aldosterone-regulated sodium reabsorption (transcriptome level), inositol phosphate metabolism (proteomic level) and 2-hexyl-5-ethyl-furan-3-sulfonic acid, and decreased betaine and myo-inositol concentrations (metabolic level). Transcriptional-metabolic and transcriptional-proteomic analyses revealed that NPs disrupted earthworm carbohydrate and arachidonic acid metabolisms. Our multi-level investigation indicates that NPs at a relatively low concentration induced toxicity to earthworms and suggests that NPs pollution has significant environmental toxicity risks for soil fauna.