Arsenic transformation behavior mediated by arsenic functional genes in landfills

Occurrence and spatiotemporal distribution of arsenic biotransformation genes in urban dust

Microbially-mediated arsenic biotransformation plays a pivotal role in the biogeochemical cycling of arsenic; however, the presence of arsenic biotransformation genes (ABGs) in urban dust remains unclear. To investigate the occurrence and spatiotemporal distributions of ABGs, a total of one hundred and eighteen urban dust samples were collected from different districts of Xiamen city, China in summer and winter. Although inorganic arsenic species, including arsenate [As(V)] and arsenite [As(III)], were found to be predominant, the methylated arsenicals, particularly trimethylarsine oxide [TMAs(V)O] and dimethylarsenate [DMAs(V)], were detected in urban dust. Abundant ABGs were identified in urban dust via AsChip analysis (a high-throughput qPCR chip for ABGs), of which As(III) S-adenosylmethionine methyltransferase genes (arsM), As(V) reductase genes (arsC), As(III) oxidase genes (aioA), As(III) transporter genes (arsB), and arsenic-sensing regulator genes (arsR) were the most prevalent, collectively constituting more than 90 % of ABGs in urban dust. Microbes involved in arsenic methylation were assigned to bacteria (e.g., Actinomycetes and Alphaproteobacteria), archaea (e.g., Halobacteria), and eukaryotes (e.g., Chlamydomonadaceae) in urban dust via the arsM amplicon sequencing. Temperature, a season-dependent environmental factor, profoundly affected the abundance of ABGs and the composition of microbes involved in arsenic methylation. This study provides new insights into the presence of ARGs within the urban dust.

Pathways and contributions of sulfate reducing-bacteria to arsenic cycling in landfills

Sulfate-reducing bacteria (SRB) are generally found in sanitary landfills and play a role in sulfur (S) and metal/metalloid geochemical cycling. In this study, we investigated the influence of SRB on arsenic (As) metabolic pathways in refuse-derived cultures. The results indicated that SRB promote As(III) methylation and are beneficial for controlling As levels. Heterotrophic and autotrophic SRB showed significant differences during As cycling. In heterotrophic SRB cultures, the As methylation rate increased with As(III) concentration in the medium and reached a peak (85.1%) in cultures containing 25 mg L-1 As(III). Moreover, 4.0-12.6% of SO42- was reduced to S2-, which then reacted with As(III) to form realgar (AsS). In contrast, autotrophic SRB oxidized As(III) to less toxic As(V) under anaerobic conditions. Heterotrophic arsM-harboring SRB, such as Desulfosporosinus, Desulfocurvibacter, and Desulfotomaculum, express As-related genes and are considered key genera for As methylation in landfills. Thiobacillus are the main autotrophic SRB in landfills and can derive energy by oxidizing sulfur compounds and metal(loid)s. These results suggest that different types of SRB drive As methylation, redox reaction, and mineral formation in landfills. These study findings have implications for the management of As pollutants in landfills and other contaminated environments.

Unraveling seasonal shifts in microbial and geochemical mediated arsenic mobilization at the estuarine sediment-water interface under redox changes

The mobilization of arsenic (As) at the sediment-water interface (SWI) is crucial for determining the accumulation of dissolved As to potentially toxic levels. However, the specific impacts of redox processes involving iron (Fe) and sulfur (S), as well as microbial activities occurring in sediments, on As mobilization at the marine SWI remain poorly understood. In this study, we investigated As mobilization at the SWI in the Changjiang Estuary during three different seasons with different benthic redox conditions. The preferential reduction of arsenate (As(V)) to arsenite (As(III)) and subsequent re-adsorption onto newly formed crystalline Fe oxides restricted As release in the As(V) reduction layer. Enhanced Fe(III) reduction in the Fe(III) reduction layer contributed to As release, while the presence of low As-high Fe-high SO42- levels resulted in As removal through adsorption onto pyrite in the sulfate reduction layer. Analysis of functional genes indicated that As(V) in sediments was released into porewater through the reductive dissolution of As(V)-bearing Fe(III) oxides by Geobacter species, followed by microbial reduction of the liberated As(V) to As(III) by microbes carrying the arrA gene. The dominant pathway governing As mobilization at the SWI in the Changjiang Estuary shifted from microbial reduction control during the hypoxic summer to Fe redox control during the aerobic autumn and winter. These findings provide valuable insights into the complex mechanisms driving As mobilization and highlight the importance of considering seasonal variations in understanding As dynamics at the marine SWI.

Regulating sludge composting with percarbonate facilitated the methylation and detoxification of arsenic mediated via reactive oxygen species

This study purposed to demonstrate the impact of reactive oxygen species (ROS) on arsenic detoxification mechanism in sludge composting with percarbonate. In this study, sodium percarbonate was used as an additive. Adding sodium percarbonate increased the content of H2O2 and OH, which the experimental group (SPC) was higher than the control group (CK). In addition, it decreased the bioavailability of arsenic by 19.10%. Metagenomic analysis found that Firmicutes and Pseudomonas took an active part in the overall compost as the dominant bacteria of arsenic methylation. ROS positively correlated with arsenic oxidation and methylation genes (arsC, arsM), with the gene copy number of arsC and arsM increasing to 7.74 × 1012, 5.24 × 1012 in SPC. In summary, the passivation of arsenic could be achieved by adding percarbonate, which promoted the methylation of arsenic, reduced the toxicity of arsenic, and provided a new idea for the harmless management of sludge.

Anthropogenic As pollution mediated by submarine groundwater discharge in a marine ranch

Arsenic (As) pollution, is a global problem, threatening human health and ecological security, especially in the bay environment with dense population and human activities. Among potential pathways of As into the bay, submarine groundwater discharge (SGD) has not received adequate attention due to its invisibility. We determined As and 222Rn activity concentrations in different water mass. Spatial variation of dissolved As concentration in the groundwater was large and attributed to the adjacent local industries. By combining 222Rn mass balance modeling with As concentrations measured, the SGD-derived As fluxes was conservatively estimated to be 1310 kg As d-1 and 5880 kg As d-1 in the dry and wet seasons, respectively. The migration of arsenic may be enhanced by rainfall and dissolved carbon. The amount of SGD derived As input to the bay was greater than the total combined As input from river discharge, atmosphere, sewage drainage, and diffusion from sediment.

Arsenate microbial reducing behavior regulated by the temperature fields in landfills

Attention should be paid to the As(V) reducing behavior in landfills under different temperature fields. In this study, microcosm tests were conducted using enrichment culture from a landfill. The results revealed that the reduction rate of As(V) was significantly affected by the temperature field, with the highest reduction rate observed at 50 °C, followed by 35 °C, 25 °C, and 10 °C. Different As cycling pathways were observed under various temperature fields. At room and medium temperatures, As4S4 was detected, indicating that both biomineralization and methylation processes occurred after As(V) reduction. However, only biogenic methylation was observed under high or low temperatures, indicating that the viability and adaptability of microorganisms varied depending on the temperature field and As contents. Pseudomonas was found to be the primary genus and dominant As(V) reduction bacteria (ARB) in all reactors. The study revealed that Pseudomonas accounted for a significant proportion of arsC genes, ranging from 87.29% to 97.59%, while arsCs genes were predominantly found in Bacillales and Closestridiales, with a contribution ranging from 89.17% to 96.59%. Interestingly, Bacillus and Clostridium were found to possess arsA genes in their metagenome-ssembled genome, resulting in a higher As(V) reducing rate under medium and high temperatures. These findings underscore the importance of temperature in modulating As(V) reducing behavior and As cycling, and could have implications for managing As pollution in landfill sites.

Co-transport of arsenic and micro/nano-plastics in saturated soil

Contaminants can co-exist and migrate together in the environment, causing complex (and sometimes unexpected) transport dynamics which challenge the efficient remediation of individual contaminants. The co-transport dynamics, however, remained obscure for some contaminants, such as arsenic and micro/nano-plastics (MNPs). To fill this knowledge gap, this study explored the co-transport dynamics of arsenic and MNP particles in saturated soil by combining laboratory experiments and stochastic model analysis. Isothermal adsorption and sand column transport experiments showed that the adsorption of arsenic by MNP particles followed the Freundlich model, with a maximum adsorption of 2.425 mg/g for the MNP particles with a diameter of 100 nm. In the presence of MNP particles, the efflux concentration of arsenic ions declined due to adsorption, where the decline rate decreased with the increasing MNP size and increased with the increasing adsorption capacity. Experimental results also showed that the 100 nm nano-plastic particles prohibited arsenic transport in saturated sand columns, while the 5 μm microplastics enhanced arsenic transport due to electrostatic adsorption and media pore plugging. A tempered time fractional advective-dispersion equation was then proposed to quantify the observed breakthrough curves of arsenic. The results showed that this model can reliably capture the co-transport behavior of arsenic with MNPs in the saturated soil with all coefficients of determination over 0.97, and particularly, the small MNP particles facilitated anomalous transport of arsenic. This study therefore improved the understanding and quantification of the co-transport of arsenic and MNPs in soil.

Arsenic (As) resistant bacteria with multiple plant growth-promoting traits: Potential to alleviate As toxicity and accumulation in rice

A currently serious agronomic concern for paddy soils is arsenic (As) contamination. Paddy soils are mostly utilized for rice cultivation. Arsenite (As(III)) is prevalent in paddy soils, and its high mobility and toxicity make As uptake by rice substantially greater than that by other food crops. Globally, interest has increased towards using As-resistant plant growth-promoting bacteria (PGPB) to improve plant metal tolerance, promote plant growth, and immobilize As to prevent its uptake and accumulation in the edible parts of rice as much as possible. This review focuses on the As-resistant PGPB characteristics influencing rice growth and the mechanisms by which they function to alleviate As toxicity stress in rice plants. Several recent examples of mechanisms responsible for decreasing the availability of As to rice and coping with As stresses facilitated by the PGPB with multiple PGP traits (e.g., phosphate and silicate solubilization, the production of 1-aminocyclopropane-1-carboxylate deaminase, phytohormones, and siderophore, N₂ fixation, sulfate reduction, the biosorption, bioaccumulation, methylation, and volatilization of As, and arsenite oxidation) are also reviewed. In addition, future research needs about the application of As-resistant PGPB with PGP traits to mitigate As accumulation in rice plants are described.

Sulfate reduction behavior in pressure-bearing leachate saturated zone

Attention should be paid to the sulfate reduction behavior in a pressure-bearing leachate saturated zone. In this study, within the relative pressure range of 0-0.6 MPa, the ambient temperature with the highest sulfate reduction rate of 50°C was selected to explore the difference in sulfate reduction behavior in a pressure-bearing leachate saturated zone. The results showed that the sulfate reduction rate might further increase with an increase in pressure; however, owing to the effect of pressure increase, the generated hydrogen sulfide (H₂S) could not be released on time, thereby decreasing its highest concentration by approximately 85%, and the duration extended to about two times that of the atmospheric pressure. Microbial community structure and functional gene abundance analyses showed that the community distribution of sulfate-reducing bacteria was significantly affected by pressure conditions, and there was a negative correlation between disulfide reductase B (dsrB) gene abundance and H₂S release rate. Other sulfate reduction processes that do not require disulfide reductase A (dsrA) and dsrB genes may be the key pathways affecting the sulfate reduction rate in the pressure-bearing leachate saturated zone. This study improves the understanding of sulfate reduction in landfills as well as provides a theoretical basis for the operation and management of landfills.

Arsenic methylation behavior and microbial regulation mechanisms in landfill leachate saturated zones

Arsenic (As) is a potential contaminant in landfill. As methylation has been considered as a detoxification mechanism to address this problem. In this study, microcosm incubation was used to simulate leachate saturation zone (LSZ) and other landfill zones scenarios to explore the As methylation behavior. The As methylation rate of LSZ is 11.75%, which is slightly higher than that of other zone of landfill (10.87%). However, the difference was greatly increased by the addition of moderate content of As(III), with values of 29.25% in LSZ and 4.61% in other zones. The microbial community structure varied greatly between zones and a higher abundance of arsM was observed in the LSZ, which enhanced As methylation. Based on the annotated As functional genes from the KEGG database, the microbial As methylated pathway was summarized. Higher relative abundances of gst and arsC promoted the formation of more trivalent As substrates, stimulating the methylation behavior for As detoxification in the LSZ. According to microbial arsM contribution analysis, unclassified_p__Gemmatimonadetes, unclassified_p__Actinobacteria, unclassified_o_Hydrogenophilales, and Intrasporangium were the primary As methylation bacteria in the LSZ, while unclassified_f__Chitinophagaceae and unclassified_c_Gammaproteobacteria were the primary contributors in other landfill zones. These results highlight the specific As methylation process in the LSZ, and these insights could improve the control of As contamination in landfill sites.

Potential of methyltransferase containing Pseudomonas oleovorans for abatement of arsenic toxicity in rice

Arsenic (As) has become natural health hazard for millions of people across the world due to its distribution in the food chain. Naturally, it is present in different oxidative states of inorganic [As(V) and As(III)] and organic (DMA, MMA and TMA) forms. Among different mitigation approaches, microbe mediated mitigation of As toxicity is an effective and eco-friendly approach. The present study involves the characterization of bacterial strains containing arsenite methyltransferase (Pseudomonas oleovorans, B4.10); arsenate reductase (Sphingobacterium puteale, B4.22) and arsenite oxidase (Citrobacter sp., B5.12) activity with plant growth promoting (PGP) traits. Efficient reduction of grain As content by 61 % was observed due to inoculation of methyltransferase containing B4.10 as compared to B4.22 (47 %) and B5.12 (49 %). Reduced bioaccumulation of As in root (0.339) and shoot (0.166) in presence of B4.10 was found to be inversely related with translocation factor for Mn (3.28), Fe (0.073), and Se (1.82). Bioaccumulation of these micro elements was found to be associated with the modulated expression of different mineral transporters (OsIRT2, OsFRO2, OsTOM1, OsSultr4;1, and OsZIP2) in rice shoot. Improved dehydrogenase (407 %), and β-glucosidase (97 %) activity in presence of P. oleovorans (B4.10) as compared to arsenate reductase (198 and 50 %), and arsenite oxidase (134 and 69 %) containing bacteria was also observed. Our finding confers the potential of methyltransferase positive P. oleovorans (B4.10) for As stress amelioration. Reduced grain As uptake was found to be mediated by improved plant growth and nutrient uptake associated with enhanced soil microbial activity.

Geogenic arsenic and arsenotrophic microbiome in groundwater from the Hetao Basin

High arsenic (As) in groundwater is an environmental issue of global concern, which is closely related to microbe-mediated As biogeochemical cycling. However, the distribution of genes related to As cycling and underlying microbial As biogeochemical processes in high As groundwater remain elusive. Hence, we profiled the As cycling genes (arsC, arrA, and aioA genes) and indigenous microbial communities in groundwater from a typical high As area, the Hetao Basin from China, using amplicon sequencing and qPCR techniques. Here, we revealed the significant difference in microbial community structure between low As groundwater samples (LG) and high As groundwater samples (HG). Acinetobacter, Thiovirga, Hydrogenophaga, and Sulfurimonas were dominant in LG, while Aquabcterium, Acinetobacter, Sphingomonas, Pseudomonas, Desulfomicrobium, Hydrogenophaga, and Nitrospira were predominant in HG. Shannon and Chao indices of the microbial communities in HG were significantly higher than those of in LG. Alpha diversity and abundance of arsC and arrA genes were higher than those of aioA genes. The significant positive correlation was uncovered between the abundances of arsC and aioA genes, suggesting the cooccurrence of As functional genes in groundwater. Sphingopyxis, Agrobacterium, Klebsiella, Hoeflea, and Aeromonas represented the dominant taxa within the As (V) reducers communities. Distance-based redundancy analysis showed that ORP, pH, As_tot, Mn, and DOC were the key factors shaping the diverse microbial populations, while ORP, S^2-, As(III), Fe(II), NH₄⁺, pH, Mn, SO₄^2-, As(V), temperature, and P as the main drivers affecting arsenotrophic microbiota. This work provides an insight into microbial communities linked to As biogeochemical processes in high As groundwater, playing a fundamental role in groundwater As cycling.

Microbial mediated arsenate reducing behavior in landfill leachate-saturated zone

As(V) reduction mediated by microorganisms might be an essential process in resisting As toxicity since As(V) is the major species in the landfill. LSZ has been considered as a trigger of all types of microbial activity inside a landfill site. This research investigated the microbial As(V)-reducing behavior in LSZ. The results revealed that higher As(V)-reduction efficiency in higher As(V) content-stress LSZ scenario. The corresponding microbial diversity also varied with the As(V) content. The microbial community structure was related to arrA and arsC distribution, which encode respiratory As(V) reductase and cytoplasmic As(V) reductase, respectively. The landfill As bio-reduction pathways were modeled, as well as the As functional gene distribution among different As(V) contents at different landfill stages. The C, N, and S metabolic processes generally affected the As(V)-resistance genes distribution. Thiosulfate oxidation, denitrification, and dissimilatory nitrate reduction positively affected arsC, while dissimilatory sulfate reduction and methanogenesis trended to play a negative role. This research provides new insight into As(V) bio-reduction inside a landfill site in terms of functional genes distribution and correlation with nutrient elements metabolic processes.

Interaction between arsenic metabolism genes and arsenic leads to a lose-lose situation

Microorganisms are essential for modifying arsenic morphology, mobility, and toxicity. Still, knowledge of the microorganisms responsible for arsenic metabolism in specific arsenic-contaminated fields, such as metallurgical plants is limited. We sampled on-field soils from three depths at 70 day intervals to explore the distribution and transformation of arsenic in the soil. Arsenic-metabolizing microorganisms were identified from the mapped gene sequences. Arsenic metabolism pathways were constructed with metagenomics and AsChip analysis (a high-throughput qPCR chip for arsenic metabolism genes). It has been shown in the result that 350 genera of arsenic-metabolizing microorganisms carrying 17 arsenic metabolism genes in field soils were identified, as relevant to arsenic reduction, arsenic methylation, arsenic respiration, and arsenic oxidation, respectively. Arsenic reduction genes were the only genes shared by the 10 high-ranking arsenic-metabolizing microorganisms. Arsenic reduction genes (arsABCDRT and acr3) accounted for 73.47%-78.11% of all arsenic metabolism genes. Such genes dominated arsenic metabolism, mediating the reduction of 14.11%-19.86% of As(V) to As(III) in 0-100 cm soils. Arsenic reduction disrupts microbial energy metabolism, DNA replication and repair and membrane transport. Arsenic reduction led to a significant decrease in the abundance of 17 arsenic metabolism genes (p < 0.0001). The critical role of arsenic-reducing microorganisms in the migration and transformation of arsenic in metallurgical field soils, was emphasized with such results. These results were of pronounced significance for understanding the transformation behavior of arsenic and the precise regulation of arsenic in field soil.

Localized intensification of arsenic methylation within landfill leachate-saturated zone

Leachate-saturated zone (LSZ) of landfills is a complicated biogeochemical hotspot due to the continuous input of electron donors and acceptors from the top refuse layer with leachate migration. In this study, the methylation behavior of the arsenic (As) was investigated. The results indicate that As-methylation processes are influenced by temperature fields in LSZ. The dimethylarsinic acid biotransformation capability can be enhanced with an increase in temperature. Microbial diversity, quantification of functional gene (arsM), and co-occurrence network analysis further characterized the drivers of As methylation in LSZ. As-biogeochemical cycle pathways, as well as As-functional gene distribution among different temperature fields, were modeled on the basis of KEGG annotation. Binning analysis was further employed to assemble As-methylated metagenomes, enabling the identification of novel species for As methylation in landfills. Then, 87 high-quality draft metagenome-assembled genomes (MAGs) were reconstructed from LSZ refuse samples; nearly 15 % (13 of 87) belonged to putative As-methylates functional MAGs. Combined with the model of the As-biogeochemical cycle, nine putative functional species could complete methylation processes alone. The findings of this study highlighted the temperature influence on the As-methylation behavior in LSZ and could facilitate the management of As contamination in landfills.

The ZrO2 NPs enhanced the risk of arsenate by promoting its accumulation and reducing its detoxification during food chain transfer from Daphnia magna to zebrafish

Arsenic (As) can co-occur with zirconium dioxide nanoparticles (ZrO₂ NPs) in aquatic environments, but their combined influence along the aquatic food chain is barely explored. This study constructed water flea Daphnia magna - zebrafish Danio rerio to evaluate the impact of ZrO₂ NPs on the accumulation, trophic transfer, transformation, and detoxification of arsenate (As(V)). The zebrafish were fed D. magna exposed to As(V), ZrO₂ NPs, or As(V) + ZrO₂ NPs for 20 d. Results demonstrated that ZrO₂ NPs significantly facilitated total As and As(V) sorption in D. magna and in tissues of zebrafish. ZrO₂ NPs enhanced the transformation of inorganic arsenic (iAs) to monomethylated acid (MMA), while decreased synthesis of arsenobetaine (AsB) in tissues, leading to iAs increased. Co-exposed As(V) and ZrO₂ NPs facilitated upregulation of absorption-related genes (aqp7) and As biotransformation-related genes (gst, gss), and detoxification and oxidative stress-related genes (mt2, cat, sod1 and sod2). Therefore, genetic expression coupling with biotransformation for the first time demonstrated that As(V) combined with ZrO₂ NPs led to increased harm to D. magna and zebrafish and amplified the ecological risks of As(V) along the aquatic food chain. Attention should be paid to the combined toxicity of As(V) and ZrO₂ NPs in aquatic environment.

A five-year investigation of water quality and heavy metal mass flux of an industrially affected river

This study investigated the water quality parameters (dissolved oxygen, electrical conductivity, salinity, pH, and temperature) and the mass flux of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in five years (2015-2019) of the Houjing River. The river flows through a heavily-industrialized zone in Kaohsiung City in southern Taiwan. The surface water was sampled 4 times per year from five sampling locations: upstream sites (H1 and H2), industrial wastewater discharge point sites (H3 and H4), and downstream (H5). Our findings show that the water quality parameters improved in the study period, especially dissolved oxygen. However, some parameters, such as electrical conductivity (mean = 1152.50 ± 414.21 μS cm^-1), were still higher than the Taiwan water quality irrigation standards. The heavy metal pollution was investigated in the aspect of mass fluxes and sources contribution. The spatial variation of the total heavy metal mass flux increased gradually from upstream to downstream, with H5 having the highest total mass flux of 74.1 kg d^-1. H2, located near an industrial zone, had a total mass flux of 33.7 kg d^-1 and contributed to the most Ni, Cr, Pb, Zn, and Hg fluxes. This study indicates that the water quality improvements observed are still not enough to meet the regulations. Stricter enforcement is required as well as further investigation to identify any illegal pollution sources.

Microbes drive changes in arsenic species distribution during the landfill process

Landfills are considered an anthropogenic source of arsenic (As). The As species mediated by microbes in landfills vary significantly in toxicity. Based on random matrix theory, 16S rRNA genes were used to construct four microbial networks associated with different stages over 12 years of landfill ages. The results indicated that network size and microbial structure varied with landfill age. According to the network scores, about 208 taxa were identified as putative keystones for the whole landfill; the majority of them were Firmicutes, which accounted for 66.8% of all specialists. Random Forest analysis was performed to predict the keystone taxa most responsible for As species distribution under different landfill conditions; 17, 10 and 14 keystone taxa were identified as drivers affecting As species distribution at early, middle, and later landfill stages, respectively.

Drivers and ecological consequences of arsenite detoxification in aged semi-aerobic landfill

Microbial populations responsible for arsenite [As(III)] detoxification were examined in aged refuse treated with 75 μM As(III) under semi-aerobic conditions. As(III) was rapidly oxidized to As(V) via microbial activity, and substantial As was fixed in the solid phase. The abundance of arsenite oxidase genes (aioA) was about four times higher in the moderate As(III) stressed treatment than in the untreated control. Network analysis of microbial community 16S rRNA genes based on MRT (random matrix theory) further illuminated details about microbe-microbe interactions, and showed six ecological clusters. A total of 166 "core" taxa were identified by within-module connectivity and among-module connectivity values. When compared with the control treatment without As(III), 12 putative keystone operational taxonomic units were positively correlated with As(III) oxidation, of which 10 of these were annotated to genera level. Eight genera were associated with As(III) detoxification: Pseudomonas, Paenalcaligenes, Proteiniphilum, Moheibacter, Mobilitalea, Anaerosporobacter, Syntrophomonas and Pusillimonas. Most of those putative keystone taxa were rare species in landfill, which suggests that low-abundance taxa might significantly contribute to As(III) oxidation.

Metallothionein Attenuated Arsenic-Induced Cytotoxicity: The Underlying Mechanism Reflected by Metabolomics and Lipidomics

Arsenic ions (As³⁺) have been recognized as a hazard that threatens the health of humans. Metallothionein (MT) rich in cysteine may provide favorable binding sites for chelation of As³⁺. However, the influence of MT on As³⁺-induced toxicity and the underlying mechanism are poorly understood, especially at the metabolic level. Herein, the effects of MT on As³⁺-induced toxicity were evaluated. Cell viability analysis suggested that MT alleviated As³⁺-induced cytotoxicity. The metabolic response of PC12 cells to As³⁺ investigated by lipidomics and metabolomics indicated that the presence of As³⁺ disrupted phospholipids metabolism and induced cell membrane damage. Moreover, energy and amino acid metabolism were perturbed by As³⁺. The perturbation of As³⁺ on metabolism was further illustrated by the decrease of the mitochondrial membrane potential and the rise of cellular reactive oxygen species (ROS). On the contrary, MT rescued As³⁺-induced metabolic disorder and suppressed ROS accumulation. In addition, the binding process between As³⁺ and MT was characterized. The results proved that the As³⁺-MT complex was formed and chelated As³⁺-scavenged ROS, thus alleviating the toxic effects of As³⁺. These results revealed that MT would be a potential agent to reduce As³⁺-induced cytotoxicity.