Insight into the environmental fate, hazard, detection, and sustainable degradation technologies of chlorpyrifos—an organophosphorus pesticide

Pesticides play a critical role in terms of agricultural output nowadays. On top of that, pesticides provide economic support to our farmers. However, the usage of pesticides has created a public health issue and environmental hazard. Chlorpyrifos (CPY), an organophosphate pesticide, is extensively applied as an insecticide, acaricide, and termiticide against pests in various applications. Environmental pollution has occurred because of the widespread usage of CPY, harming several ecosystems, including soil, sediment, water, air, and biogeochemical cycles. While residual levels in soil, water, vegetables, foodstuffs, and human fluids have been discovered, CPY has also been found in the sediment, soil, and water. The irrefutable pieces of evidence indicate that CPY exposure inhibits the choline esterase enzyme, which impairs the ability of the body to use choline. As a result, neurological, immunological, and psychological consequences are seen in people and the natural environment. Several research studies have been conducted worldwide to identify and develop CPY remediation approaches and its derivatives from the environment. Currently, many detoxification methods are available for pesticides, such as CPY. However, recent research has shown that the breakdown of CPY using bacteria is the most proficient, cost-effective, and sustainable. This current article aims to outline relevant research events, summarize the possible breakdown of CPY into various compounds, and discuss analytical summaries of current research findings on bacterial degradation of CPY and the potential degradation mechanism.


Introduction
Pesticide exposure and poisoning are causing significant damage to plants, animals, and human health (Jaacks et al. 2019).Pesticides have been reported by analyzing their remaining concentrations in water, soil, and air, and they endanger the biological system and human health through the food chain (Schleiffer and Speiser 2022;Chaudhari et al. 2023).
Pesticides have contaminated rivers, lakes, and surrounding agricultural areas, producing excessive pesticide concentrations in aquatic systems (Sruthi et al. 2017).Humans are exposed to pesticides such as hexachlorocyclohexane and dichloro diphenyl trichloroethane through the ingestion of biota from polluted aquatic systems, which can result in multiple health problems, including endocrine disorders, birth deficiencies, prostate and uterine cancer, and reduced sperm count (Jayaraj et al. 2016).
Chlorpyrifos (CPY) is an organophosphate pesticide utilized broadly for decades to prevent various agricultural pests, including corn, soybeans, fruit trees, and other crops.It is also used in non-agricultural locations, such as golf courses, and for public health to control mosquitoes and other disease-carrying insects (Mora-Gutiérrez et al. 2022).CPY was listed in the USA in 1965 for the first time and is registered for use in more than 100 countries worldwide (Solomon et al. 2014).Every year, 2 million tonnes of pesticides are used worldwide to prevent crop loss.However, only around 0.1% of these compounds operate on targeted species and 90-99% stay in the atmosphere due to their Organophosphates (OPs) are currently the most usually applied pesticide globally.Pesticides containing OP are primarily used in farming to resist essential insect pests (Sasikala et al. 2012;Sharma et al. 2019).Organophosphate has almost substituted organochlorine (OC) pesticides that are banned from usage due to their potential toxicity, bioaccumulation, and persistence in the ecosystem (Carvalho 2017).CPY is used in pest management in cities and homes, grass care, and as a termiticidal barrier in, around, and under structures.CPY is India's fourth most commonly used pesticide after monocrotophos, acephate, and endosulfan.It belongs to the phosphorothioate group of organophosphate pesticides (Hasan et al. 2022).CPY consumption increased when the Government of India banned several organochlorine insecticides like DDT, Aldrin, and chlordane.CPY is effective by ingestion, contact, and vapor action and has various insecticidal properties (Tzanetou and Karasali 2022).
CPY is a carcinogenic bio-persistent compound whose exposure has been linked to various nerve syndromes in humans (Hassan et al. 2022).The mechanism of toxicity of CPY is well-studied as they act as enzymatic inhibitors and target the central nervous system by blocking the action of the acetylcholine esterase enzyme (essential for the diffusion of nerve impulses); the inhibition occurs through the irreversible binding to the catalytic site of the enzyme.Recent studies on CPY environmental fate and toxicity are accessible in the scientific literature; extensive usage of pesticides is injurious to the ecosystem and animals; therefore, it is critical to eradicate them (Sasikala et al. 2012).
The water samples from the Tighra reservoir in Gwalior, India, were analyzed during various seasons to determine the levels of CPY and methyl parathion.The mean concentrations of CPY were observed 12.27 ng/L, 3.03 ng/L, 3.48 ng/L, and 2.51 ng/L during winter, summer, pre, and post-monsoon, correspondingly (Mamta et al. 2015).CPY was also perceived in fish (24.42 ng/g) from the Jucar River, Spain (Belenguer et al. 2014).CPY was also detected in vegetable and fruit samples collected from farmers' markets in Egypt (El-Sheikh et al. 2022) and in ready-made foods from markets (El-Sheikh et al. 2023).
There are many approaches for CPY degradation, such as chemical treatment, photodecomposition, volatilization, and pyrolysis.However, most are ineffective, costly, and damaging to the environment, making them unsuitable for removing CPY contamination at low concentrations (Abraham and Silambarasan 2013).Physicochemical (innovative oxidation method) and biological treatment methods have been used extensively in recent years to eliminate pesticides.Bioremediation of pesticides has emphasized enhancing ecosystem and soil quality since it is an economical and ecologically benign strategy (Nandhini et al. 2021).
According to new research, CPY, which was earlier demonstrated to be resilient to accelerated deprivation, undergoes enhanced microbe-mediated decay (Akbar and Sultan 2016).Several microorganisms such as Bacillus, Acinetobacter, Pseudomonas, Flavobacterium, Sphingomonas, and Agrobacterium sp. are being described for the transformation of CPY (Fulekar and Geetha 2008;Maya et al. 2011;Pino et al. 2011).

Characteristics of chlorpyrifos
The properties of CPY (O,O-diethyl O-3,5,6-trichloro-2-pyridinyl phosphorothioate) are the key factors determining how the substance behaves in the environment.It is a crystalline organophosphate pesticide used broadly worldwide as an urban and domestic pest controller (Moradeeya et al. 2017).CPY is mainly applied in France to treat fruits, vegetables, and vineyards.CPY Oxon, one of its principal metabolites, is a member of the aryl phosphorothioate family of chemical compounds, and one of its functional groups is thiophosphoric acid (Kumar et al. 2016).It resembles crystalline white powder and smells like rotting eggs or mercaptans (Jaiswal et al. 2017).CPY is marketed under several brand names, including Dursban, Lorsban, and Suscon, and also comes in many formulations, including emulsifiable concentrates, wettable powder, and granular formulation (Sud et al. 2020).CPY has low solubility in water (2 mg/L at 25 °C) but is soluble in benzene, maize oil, methanol, acetonitrile, acetone, and dimethyl sulfoxide (Briceño et al. 2012;Ubaid ur Rahman et al. 2021).Table 1 demonstrates the physico-chemical characteristics of CPY.

Environmental fate of chlorpyrifos
The environmental fate of CPY consists mainly of sorption-desorption to soil matrix, scattering into deeper soil layers, percolating into groundwater, plant uptake, volatilization, and deprivation (Cycoń et al. 2017).Many studies have shown that the environmental fate of CPY is heavily influenced by its persistence, movement, and bioavailability, which is a complicated procedure influenced by numerous variables other than its characteristics (Wang et al. 2013).The physical and chemical interface among the chemicals and other elements defines the fate of CPY in the environment.CPY is dispersed throughout the environment and undergoes many changes, including oxidation, photolysis, photodegradation, photomineralization, biotransformation, and associated metabolic processes in living things such as plants, animals, and humans (Lian et al. 2021).Adsorption, volatilization, leaching, runoff, absorption, and degradation are the primary routes (Bhende et al. 2022;Wang et al. 2023).Despite their low concentration, this contaminant puts a significant risk to environmental and human health due to their incomplete removal during the treatment.Figure 1 shows the environmental fate of CPY.

Persistence of chlorpyrifos in the environment and its effects on soil quality
CPY has a brief to moderate persistence due to many degradation mechanisms that may co-occur (Shen et al. 2022).Volatilization, photolysis, abiotic hydrolysis, and microbiological deprivation are some of the main degradation processes for CPY.Estimates of CPY half-lives in soils under laboratory settings vary from 2 to 1575 days, liable on the characteristics of the soil (Solomon et al. 2014).CPY dissipation in the soil is biphasic, with a preliminary fast deprivation trailed by a later breakdown (Bose et al. 2021).CPY is relatively persistent and has a half-life of 60 to 120 days.However, depending on the soil type, temperature, and additional features, it may vary from 2 weeks to a year.In soils with a higher pH, CPY is less persistent.Soil texture and organic matter concentration did not affect the half-life of CPY.The half-life in anaerobic soils was 15 and 58 days in loam and clay soil, respectively (Mali et al. 2022).The ultraviolet radiation, chemical hydrolysis, and soil microbes help in the degradation of CPY that has been absorbed.CPY has high adsorption to soil particles; as a result, it remains steady in soils and is improbable to leak or pollute groundwater.TCP, CPY's primary metabolite, poorly binds to soil particles and seems moderately movable and persistent in soils (Wołejko et al. 2022).The USEPA believes there is inadequate evidence to properly evaluate CPY's environmental fate.Because CPY is firmly adsorbent in soil, it is unlikely to leach substantially.The loss will be aided by volatilization from the soil surface.CPY microbial metabolism might have a half-life of up to 279 days, depending on soil type (Lara-Moreno et al. 2022).Table 2 shows the environmental fate properties of CPY.
According to the literature, CPY affects the microbial population in soil and hinders critical nutrient cycling (John and Shaike 2015).CPY-induced reactive oxygen species production directly contributes to nitrase activity reduction by preventing the gene expression involved in the fixation of soil nitrogen (Lu et al. 2020).According to Riah et al. (2014), CPY may also alter the enzymatic activities in soil, like phosphatases and β-glucosidase.
CPY is also a poisonous chlorine-containing organic molecule, unlike many other phosphorus-containing chemicals, contributing to its toxicity.Chlorine's presence is problematic because of the risks of dehalogenation and the production of breakdown products and secondary metabolites.Moreover, these metabolites produced during CPY breakdown may be more hazardous than the parent molecule, and they may cross the placenta and have detrimental effects on the developing brain and immune system (Andreazza and Scola 2015).
Furthermore, new research suggests that CPY can create bound residues in soil, which might be owing to the physical immobilization of the parent molecule and its primary metabolite 3,5,6-TCP, which is mainly collected by humic acids (Wołejko et al. 2022;Zhong et al. 2022).The effects of CPY and other associated pesticides on soil quality reported in different countries are demonstrated in Table 3.

Detection of chlorpyrifos in environmental samples
Modern food safety concerns make detecting CPY residue crucial for preventing the body from absorbing the substance (Sankom et al. 2021).CPY remainder in agricultural samples is typically observed using various sophisticated techniques and tools.Gas chromatography, high-performance liquid chromatography, and GC-LC mass spectrometry are some techniques used to measure the residual levels of pesticides.GC was used to perceive CPY in green tea leaves (Cho et al. 2014); pesticides in eggplant and cucumber were detected using HPLC (Watanabe et al. 2015); and   GC-LC-MS was utilized for several agronomic foods (Li et al. 2013;El-Sheikh et al. 2022, 2023).However, these methods require a sophisticated laboratory, involve complex sample preparation, and are destructive (Lapcharoensuk et al. 2023).To prevent CPY from entering the environment, a high-precision, real-time detection technique is essential.An extremely accurate, long-lasting, and repeatable enzyme-free electrochemiluminescence (ECL) CPY sensor was developed (Concha-Meyer et al. 2019).Due to its uniform active site and high atomic dispersion, palladium (Pd) is used to produce PdSA/TiO 2 to increase its sensitivity for CPY detection.CPY can be detected with PdSA/TiO 2 at very low concentrations (0.1 ng/mL), and the existence of other OPs like dipterex, paraoxon, and monocrotophos does not affect the detection.This photocatalyst sensor has a linear range of 0.03 ng/mL to 10 g/mL.SA catalyst production's direct and labor-intensive nature indicates a high likelihood of finding CPY remainder in the environment (Ge et al. 2020).Table 4 shows the concentration of CPY residues in different biota samples.

Hazards of chlorpyrifos: an endocrine disruptor compound
CPY is one of the most widely used pesticides because it is efficient against various pests.Adverse effects on sex hormone metabolism and nervous system function have been linked to chronic, sublethal exposure to CPY.It has been linked to endocrine disruption, aberrant development, and difficulties with the testes and the brain.Degradation products of CPY may interfere with estrogen signaling in humans by binding to steroid hormone receptors like estrogen receptor alpha (ER-alpha) (Hazarika et al. 2020).Chemicals known as endocrine disruptors (EDs) have been shown to impact the development of breast cancer.Inhibition of acetylcholinesterase (AChE) is central to the harmful effects of CPY.Despite its AChE-inhibiting properties, CPY has been shown in several studies to disrupt normal development even at low concentrations (Calaf et al. 2020).
The endocrine-disrupting compounds formed during the transformation of CPY can have detrimental effects on the reproductive systems.These compounds may reduce sperm quality and fertility in male rats at doses ranging from 0.5 to 10 mg/kg/day and alter estrous cyclicity in female rats exposed to chlorpyrifos at 1 to 10 mg/kg/day doses.Similarly, these compounds may also cause thyroid hormone disruption.They may alter thyroid hormone levels in rats exposed to chlorpyrifos at 1 to 10 mg/kg/day (Leemans et al. 2019;Kongtip et al. 2021).
In a research study, male rats fed a diet containing 5.4 mg/ kg or 10 mg/kg of CPY for 30 or 90 days, respectively, had a decline in sperm count, a reduction in sperm motility, an increase in sperm deformities, and a shift in blood testosterone levels (Peiris and Dhanushka 2017).Adedara et al. (2018) reported that CPY (5 mg/kg/day) was also shown to produce alterations in testicular histology in male rats, activate lipid peroxidation, and impair the activity of antioxidant enzymes.CPY has also been shown to reduce sperm motility and create oxidative stress by destroying mitochondrial activity at a concentration of 25 µg/mL, thus decreasing the fertility of male mice (Zhang et al. 2020).Lasagna et al. (2022) have shown that CPY causes MCF-7 and MDA-MB-231 cells to undergo an epithelial-mesenchymal transition in 2D cultures and alters the expression of key molecular markers involved in this process.Using 3D culture models, CPY may predispose cancers to become more metastatic and aggressive.Through activation of estrogen receptor alpha (ER) and c-SRC, CPY at a concentration of 0.05 µM increased the quantity and size of mammospheres in MCF-7 cells.
Humans' central neurological, cardiovascular, and respiratory systems may also be harmed by CPY intoxication.It also causes skin and eye irritation.Since CPY prevents the brain enzyme acetylcholinesterase, it is very toxic to neuro-endocrine growth in pregnant and infants (Burke et al. 2017).It lingers in the ecosystem, and lasting acquaintance can result in chronic kidney disease.Pregnant women and children should avoid these chemicals by consuming organic fruits.Conferring to the Lancet Commission on Pollution and Health (LCPH), reducing pesticide exposure benefits community health and leads to long-term socio-economic benefits by reducing hospitalizations and IQ loss from neuro-endocrine pesticide-related disorders (Xu et al. 2018;Yu et al. 2019).Atabila et al. (2018) assessed CPY exposure and health hazard among twenty-one individuals in a rice field in Ghana, resulting in a low CPY exposure of 6 g/kg/day on average.For the same hazard quotient (HQ > 1), the WHO recommendation value differs from the USEPA guideline value.When individuals are exposed to CPY, there is no danger of chronic (10 g/kg/day) or acute (100 g/kg/day) health impacts, according to WHO.However, it poses a risk of chronic (0.3 g/kg/day) and acute (5 g/kg/day) health effects, conferring to USEPA.Voller (2019) discovered that CPY and carbofuran (CBF) are neuro-toxic to human neuroblastoma cells (SK-N-SH) and have synergistic effects, posing a substantial food safety issue.These two substances cause cell apoptosis and oxidative stress since cell cycle arrest leads to the buildup and formation of reactive oxygen species (ROS), which is known to induce subcellular injuries and tissue injury (Fu et al. 2019).
Exposure to CPY in people produces long-term exposure consequences even in low-dose acquaintance situations (Tsygankov et al. 2018).CPY is highly hazardous to freshwater fish, river invertebrates, and marine species.In severe toxicity studies on fish exposed to minimal doses of this pesticide, cholinesterase inhibition was found.CPY severely threatens animals and honeybees in aquatic and agricultural applications (Hossain et al. 2022); this demonstrates that CPY is a toxic substance that endangers human health while damaging the ecosystem.Several risk assessment studies on CPY were reported; however, these estimations are readily influenced by climatic change, exposure time, and CPY concentration.As a result, comprehensive updates on the dangerous level of CPY are required to identify the safe amount of CPY for people and animals.Different preventive measures must be taken to minimize the exposure and poisoning of CPY (Fig. 2).Global attention must be given to preventing exposure to and poisoning from CPY. Pesticides classified as highly hazardous (HHPs) by globally recognized classification systems are regarded to have exceptionally higher levels of acute or ongoing risks to humans or the ecosystem (Utyasheva and Bhullar 2021).Regular monitoring and surveillance of the working environment and workers' health can help identify potential risks and prevent further exposure (Foong et al. 2020).

Conventional technologies for the transformation of chlorpyrifos
There are many ways to remove CPY from the environment; however, most remediation technologies need a big area, significant operating and maintenance expenses, and substantial capital expenditures.Today's physiochemical processes include reverse osmosis, distillation, and ion exchange resins.However, their main downsides are disposal issues, membrane deformation, sludge production, handling, and technological limitations (Sheikhi et al. 2021).However, it is well established that standard techniques, such as physicochemical techniques, activated sludge breakdown, anaerobic breakdown, and air stripping, cannot wholly degrade organic contaminants (Khan and Pathak 2020;Zhou et al. 2023).
The other methods, including adsorption and coagulation, just concentrate the contaminants by transporting them to another phase; nevertheless, they do not "remove" them entirely.The techniques, which include filtration, sedimentation, chemical, and membrane technologies, are expensive to operate and produce hazardous secondary pollutants that pollute the environment (Nehra et al. 2021).The different approaches for removing and transforming CPY are listed in Table 5.

Bioremediation techniques for chlorpyrifos biotransformation
Microbes transform CPY by using them as a source of carbon and electron suppliers, though their decomposition is influenced by various environmental and physiological, biochemical, and molecular factors.Pesticide-degrading microbes are being recognized and described in many labs across the globe.However, DNA sequencing technology has advanced our knowledge of the processes, existence, and recognition of efficient microbes for the degradation of contaminants (Huang et al. 2018;Pathak et al. 2022).Figure 3 illustrates the CPY transformation process and its ultimate fate in the environment.Biotic and abiotic variables influence the fate of CPY in the atmosphere.Through biodegradation, CPY is mainly destroyed in the environment by microbes (Farhan et al. 2021).
Organophosphates such as CPY are easily water-soluble after natural breakdown, making them more prone to human ingestion and potentially causing severe health issues.The deprivation of organophosphates by biotic or physicochemical means has been extensively studied all around the globe  Fast and most effective, no end product Costly, the only concern is the removal of nanomaterials (Kaushal et al. 2021).Microorganisms' capacity to terminate these compounds in controlled circumstances is favored since it is faster than physical and chemical approaches (Kumar et al. 2022).Microorganisms break down or eliminate most pesticides by utilizing them as a single source of C, N, and K (Anjum et al. 2022).

Bacterial degradation
CPY is an abstemiously hazardous insecticide with a mammalian average toxic dosage (LD50) of 32-1000 mgkg −1 (WHO 2020).Several investigators have dedicated themselves to utilizing various microbial species for the biodegradation of CPY (Table 6).Bacterial populations' ability to break down contaminants more proficiently is owing to their incredible endowment of catabolic genes, which allow them to survive in a variety of biological niches across a range of pH, temperature, oxygen, and metal concentrations (Ibrahim et al. 2015;Zhang et al. 2021).As a result, they may be used for CPY biodegradation due to their tolerance and aptitude (Baquero et al. 2021).
According to Walia et al. (2018), CPY (1000 mg/L) has an inhibitory effect on plant growth-promoting bacteria, which unquestionably lowers crop productivity by blocking the functions of plant growth-promoting bacteria (PGPB).Swarupa and Kumar (2018) tested the impacts of CPY on plant growth-promoting rhizobacteria (PGPR) from the Okra (Abelmoschus esculentus) plant.They have isolated three bacterial isolates, namely O-1, O-2, and O-3.Growth tests using Luria Bertani (LB) agar and M9 minimal medium (M9MM) augmented with various concentrations of CPY reveal that bacterial isolates O-1 and O-2 can handle high CPY concentrations up to 5000 mg/L.This finding is supported by similar investigations from other researchers who have described PGPR lenience to numerous pesticides up to 600 mg/L (Chennappa et al. 2014;Tripti et al. 2015;Shahid and Saghir Khan 2017).Deng et al. (2015) obtained Stenotrophomonas sp.G1 isolated from industrial sludge and revealed that this species fully decomposed methyl parathion, methyl paraoxon, diazonin, and phoxim, as well as CPY (63%), profenofos (38%), and triazophos (34%) within 24 h at a dose of 50 mgL −1 .
Jabeen et al. ( 2015) identified microbial strain HN3 that effectively decomposed CPY under various environmental conditions.Temperature (37 °C) and pH (7) were shown to be optimal for CPY breakdown.Hossain et al. (2015) observed BG1, BG4, and PD6 strains for the degradation of CPY.The degradation rates for 20 mgL −1 and 50 mgL −1 of CPY were determined to be highest on the second day by all isolates throughout the experimental period.Sasikala et al. (2012) developed a consortium of various bacterial species that was able to hydrolyze CPY (500 mgL −1 ) to CP-oxon and diethylphosphorothioate in a liquid medium and TCP in the soil at pH 7 and temperature of 37 °C.Maya et al. (2011) 2012) identified 35 bacterial species from the sludge of the pesticides production drain.Pseudomonas sp.(WW5) was shown to be the most effective CPY degrader out of 35 strains, degrading 94% of 400 mgL −1 CPY in 18 days.It was shown that glucose causes CPY cometabolism.At the same time, a higher pH (8) and a large inoculum size (108 CFUmL −1 ) resulted in the most effective degradation.Stenotrophomonas maltophilia has also shown the degradation of various concentrations of CPY in both soil and water (Dubey and Fulekar 2012).Nabil et al. (2011) cultivated five microbial strains and used mineral salt (MS) medium to examine how these strains degraded CPY.The bacterial isolates exhibited considerable growth in mineral salt (MS) medium augmented with 100-300 mgL −1 CPY as the only carbon source.They also looked at the effects of eight control factors on Pseudomonas stuzeri's CPY degradation.Anwar et al. (2009) used Bacillus pumilus for the biodegradation of CPY, and the strain used CPY as its only carbon source, while glucose, nutritional broth, and yeast extract were co-metabolized.Singh et al. (2009) explored the capacity of Pseudomonas sp. to damage and produce biosurfactants.The addition of bio-surfactant resulted in a 98% rise in CPY decomposition.Xu et al. (2008) applied Paracoccus sp. to degraded CPY and demonstrated that this strain mineralizes CPY entirely and degrades other insecticides also.

Enzymatic degradation of chlorpyrifos
Enzymatic deprivation of CPY involves the breakdown of the chemical compound by enzymes formed by microbes.Several enzymes are involved in the degradation procedure, including esterases, dehalogenases, and hydrolases.These enzymes can break down CPY into less toxic or nontoxic compounds that can be further degraded or assimilated by microorganisms in the environment (Thakur et al. 2019).Microorganisms, with their hydrolytic and oxidative enzymes, show a vital role in CPY breakdown.The use of enzymes for CPY remediation has some benefits, like more efficacy and economical and environmental friendliness (Huang et al. 2021).The hydrolytic enzymes such as OP hydrolase, which includes O-phenylenediamine dihydrochloride, mevalonate pyrophosphate decarboxylase, methyl parathion hydrolase, and others, hydrolyze OP composed of PeO, PeF, and PeS linkage (Yongliang et al. 2013).
OP acid anhydrase, also known as paraoxonase, esterase, phosphotriesterase, diisopropyl fluorophosphatase, somanase, and parathion hydrolase, is a hydrolase generated by a variety of aquatic organisms that can hydrolyze a variety of OPs (Zheng et al. 2022).Serdar and Gibson (1985) obtained the first OPH from the plasmid of Pseudomonas diminuta MG.Mulbry and Karns (1989) isolated OPH from Flavobacterium sp., which has 1693 base pairs and one open reading frame.Guha et al. (1997) described the biodegradation of CPY using a plasmid obtained from Micrococcus species.A new phosphotriesterase (PTE) enzyme was discovered in Enterobacter strain B-14.The deprivation ability of the PTE enzyme is determined by a gene whose sequence differs from that of the organophosphate degradative genes that have been widely studied (Yadav et al. 2016).
Numerous enzymes have been described to destroy CPY, including esterases, hydrolases, oxidases, and peroxidases.The enzymatic degradation of CPY has been investigated in different systems, including soil, water, and sediments (Gao et al. 2012).
Carboxylesterase (CE) is an essential enzyme in the hydrolysis of CPY.Carboxylesterase has been isolated from various organisms, including bacteria, fungi, and mammals.Many studies have reported the usage of bacterial esterases for CPY degradation (Bhatt et al. 2019).
Acetylcholinesterase (AChE) is another esterase reported to degrade CPY.AChE is a crucial enzyme in the nervous system that regulates the neurotransmitter acetylcholine.It has been reported that AChE can hydrolyze the phosphate group of CPY, resulting in pesticide breakdown (Kaushal et al. 2021).Hydrolases are another group of enzymes described to degrade CPY (Fan et al. 2018).Hydrolases catalyze the hydrolysis of various chemical bonds, including ester, amide, and glycosidic bonds.Several hydrolases have been stated for the degradation of CPY, including lipases, proteases, and amidases (Shukla et al. 2022).Lipases are a cluster of hydrolases that catalyze the hydrolysis of ester bonds in lipids.Lipases have been testified for CPY degradation by hydrolyzing the ester bond (Bhandari et al. 2021).
Oxidases and peroxidases are other groups of enzymes described to degrade CPY.Oxidases and peroxidases catalyze the oxidation of various organic compounds, including pesticides.Several oxidases and peroxidases have been defined for the degradation of CPY, including laccase, horseradish peroxidase, and manganese peroxidase (Morsi et al. 2020).

Biotechnological approaches for chlorpyrifos degradation: case studies
CPY has been connected to several environmental and health issues, including soil and water contamination, neurological damage, and cancer.Biotechnological approaches for CPY degradation offer a promising solution for reducing its influences on the ecosystem and humans (Wołejko et al. 2022).
Here are some case studies that depicted CPY degradation using different biotechnological approaches: i. Biodegradation of chlorpyrifos by Hortaea sp.B15 (Hadibarata et al. 2023).
The study defines how Hortaea sp.B15-mediated CPY breakdown was affected by salinity, pH, temperature, and surfactant, as well as by enzyme activity and the metabolic route.In a 100 mg/L CPY-augmented culture, the most incredible bacterial growth (4.6 × 10 16 CFU/mL) was attained after 20 h of incubation.A first-order rate equation with an R 2 value of 0.95-0.98 was the bestsuited model and practical technique to describe the kinetics of CPY biodegradation under typical circumstances.The clearance rate was high (91.1%),and the highest total count was 3.8 × 10 16 CFU/mL at pH 9, which was the ideal pH for CPY biodegradation.The salinity of the culture had no discernible impact on bacterial growth or breakdown.Maximum CPY-breakdown (89.5%) and bacterial growth (3.8 × 10 16 CFU/mL) were attained in the existence of the non-ionic surfactant Tween 80. CPY was degraded by Hortaea sp.B15 using metabolites such as 3,5,6-trichloropyridin-2-ol and 2-pyridinol.The results suggested that Hortaea sp.B15 is recommended for the biodegradation of pesticides.
ii. Behavior of chlorpyrifos and TCP in a sodium-dodecyl sulfate-electrokinetic soil washing system (Vidal and Báez 2023).
The remediation of CPY from soil was investigated using an electro-kinetic soil washing method with alternating polarity (EKSW-AP) that uses the anionic surfactant SDS in the washing solution.An electric field of 1 V cm −1 was applied between the electrodes for 15 days in two different kinds of soil.The significant findings of this study demonstrated that SDS does not increase the likelihood of mobilizing CPY and TCP during the EKSW-AP treatment because of the low concentration it retains after adsorption on soils.Without current implementation, the recovery of CPY in the reference systems was close to 100% of the added mass.However, in the EKSW-AP systems, recoveries were closer to 80%.In untreated soils, kinetic experiments only found the production of TCP and no other breakdown products.As a result, the EKSW-AP procedure probably enhanced the oxidation of TCP and CPY, leading to the development of a different, more polar by-product in the collector wells.The results show that the EKSW-AP does not considerably change the physicochemical characteristics of the soils with the application of SDS.
The ability of Bacillus cereus AKAD 3-1, isolated from the soybean rhizosphere, to break down CPY was observed.Response surface methodology (RSM) and artificial neural networks (ANNs) were applied to improve and validate various process variables.The preliminary pesticide concentration, pH, and inoculum size influence the breakdown.Under ideal circumstances, the bacterial strain successfully removed glyphosate and CPY 94.52% and 83.58%, respectively.Central-composite design (CCD-RSM) and ANN techniques have performed well in modeling and optimizing growth circumstances.For CPY, the best ANN-GA model produced an R 2 value of 0.99; for RSM, the values were 0.96 and 0.95, respectively.The biodegradation of CPY and glyphosate was found to be significantly (p < 0.05) impacted by the process variables.According to GC-MS analysis, the strain initially changed CPY into 3,5,6-trichloro pyridin-2-ol and O,O-diethyl O-hydrogen phosphorothiate.These intermediate metabolites were later totally mineralized and broken down into harmless byproducts.Therefore, the findings of this research demonstrated the potential of B. cereus AKAD 3-1 in the CPY degradation.iv.Characterization of OPs sorption of potato peel biochar for chlorpyrifos removal (Singh et al. 2022).CPY was treated with biochar using several physical factors, and the treatment was then improved using the response surface approach and Box-Behnken design (BBD).After 24 h of treatment, 72.06% of the pesticide content of 1346.85 g/ml was shown to be removed with a biochar concentration of 1.04 mg/ml at pH 5.04.FTIR, SEM-EDX, and proximal and final analyses described biochar.The peel and biochar's surface shape and minerals were visible using SEM-EDX examination.Potato peel has bigger pores per microgram than charcoal, which contains many holes of different sizes.
The occurrence of biochar enhanced morphology, biomolecules, and photosynthetic pigments.Reduced glucose and protein content of treated leaves is evidence of improved nutrient translocation in plants treated with biochar.A study on the biocompatibility of CPY in fish erythrocytes revealed that pesticide-treated biochar caused 43.26% hemolysis.This tactic is most useful in real-world situations when used in acidic soil regions.
A commercial bio-product called biochar may help agriculture, industry, and the energy area and lead to a bio-based economy with less contamination overall.v. Chlorpyrifos biodegradation using Bacillus cereus and Klebsiella pneumoniae (Elshikh et al. 2022).
Bacillus cereus CP6 and Klebsiella pneumoniae CP19, two pesticide-degrading strains, were isolated and characterized using biochemical, physiological, and morphological traits and 16S rDNA sequencing.The strains B. cereus CP6 and K. pneumoniae CP19 decomposed CPY by more than 70%.In submerged fermentation, K. pneumoniae CP19 could break down CPY more quickly than B. cereus CP6.These two isolates can break down pesticides when glucose is used as a carbon source, and their biodegradation capability was most significant at neutral pH.In contrast to K. pneumoniae CP19, B. cereus CP6 used the beef extract to trigger the most incredible pesticide breakdown.Additionally, a bacterial consortium created with the help of the CP6 and CP19 strains metabolized 93.42.8% of CPY in liquid culture.The microbial consortia-infected soil deteriorated 82.3 ± 1.3% for 14 days, and maximal degradation (94.5 ± 3.3%) was attained after 16 days.vi.Dissipation of chlorpyrifos and 3,5,6 trichloro-2-pyridinol under vegetation of different aromatic grasses (Yadav et al. 2021).This research aims to explore the efficiency of the gramnegative Dyadobacter jiangsuensis to CPY transformation.The evolution of D. jiangsuensis on the minimum salt medium spiked with CPY demonstrated this strain's capacity to use CPY as its exclusive carbon source and validated its use of 3,5,6-trichloro-2-pyridinyl (TCP) using the silver nitrate assay.In an aqueous medium and a soil environment, the strain degraded CPY by 80.36% and 76.93%, respectively.The formulated strain outperformed the unformulated one in soil under microcosm conditions by degrading CPY by 21.13% more quickly.During the breakdown of CPY, the intermediate metabolites 3,5,6-trichloro-2-pyridinol (TCP), tetrahydropyridine, thiophosphate, and phenol, 1,3-bis (1,1-dimethylethyl) were found.The study identifies D. jiangsuensis as a potential organism for CPY degradation.It raises the prospect of using its formulations to clean up soil that has been contaminated with CPY.
vii.Metabolism of chlorpyrifos by Pseudomonas aeruginosa increases toxicity in zebrafish (Kharabsheh et al. 2017).
The study inspected the efficiency of Pseudomonas aeruginosa for CPY degradation in freshwater environments.HPLC analysis indicated that P. aeruginosa decomposed CPY to its principal metabolites like CPF-oxon and 3,5,6-trichloro-2-pyridinol.The rhizosphere bioremediation efficiency of ryegrass for the degradation of CPY in soil was studied using greenhouse pot culture experiments.The CPY concentration in the pot cultured soil was degraded entirely after 7 days, while the remainder of the modified concentrations (25-100 mg/kg) dropped quickly as the incubation continued until 28 days under the effect of the ryegrass mycorrhizosphere.The microbes connected to the roots in the rhizospheric zone are responsible for CPY bioremediation in soil.The microbes enduring in the rhizospheric soil spiked at 100 mg/kg were evaluated and utilized to isolate CPY debasing microbes.Pseudomonas nitroreducens PS-2 was discovered as a possible degrader utilizing the 16SrDNA BLAST method.The degradation of CPY in the inoculated rhizospheric soil was 100%, compared to 76.24%, 90.36%, and 90.80% in the noninoculated soil at starting doses of 25, 50, and 100 mg/kg at 2nd, 3rd, and 4th week correspondingly.

Potential benefits and limitations of using microorganisms for CPY-degradation
CPY poses a significant environmental concern due to its persistence and potential toxicity to non-target organisms.Fortunately, certain microorganisms have shown the ability to degrade CPY, helping to mitigate its environmental impact.The microbial breakdown of CPY is of special interest due to its significant mammalian toxicity and extensive use (Shi et al. 2019).A few of the microorganisms with their potential degradation mechanism, advantages, and limitations are listed in Table 7.

Constructed wetlands for removal of chlorpyrifos: role of plant and microbes
Constructed wetlands can be effective in removing CPY from the contaminated environment.The role of plants and microorganisms in this process is crucial (Negatu and Dugassa 2021;Zhang et al. 2023).Plants in constructed wetlands can take up and metabolize CPY, breaking it down into less harmful substances.The roots of plants offer a surface for the evolution of microbes that can also degrade the pesticide.The plants also produce oxygen, increasing aerobic bacterial growth and proficiently transforming CPY (Wang et al. 2022).
Besides plants, microorganisms are essential in the remediation of CPY from water in constructed wetlands.Microbes can transform the pesticide through a process known as biodegradation.Biodegradation involves the transformation of organic pollutants by microorganisms into simpler and less harmful substances.The microbes in constructed wetlands work with the plants to remove CPY.The plants provide habitat and nutrients for the microbes.In contrast, the microbes provide the enzymatic machinery needed to degrade the pesticide (Aziz et al. 2022).
Moreover, plants in artificial wetlands support the bed surface and improve permeability across the wetland area, promoting aerobic bacteria growth and speeding up the degradation rate (Hassan et al. 2021).According to Cooper  2016), when a three-stage bio-bed was employed as a wetland, various pesticides were removed (around 92%) from wastewater.Tang et al. (2019) observed 98% CPY elimination using Cyperus alternifolius, Canna indica, Iris pseudacorus, Juncus effusus, and Typha orientalis in recirculating vertical flow-built wetland systems.Similarly, 98% of CPY was removed by a constructed wetland planted with Polygonum punctatum, Cynodon spp., and Mentha aquatic (Souza et al. 2017).The published research attributed variations in organic carbon, moistness, application level, and bacterial activity to the variances in CPY breakdown rates (Racke 1993).
Overall, constructed wetlands may be an efficient and viable system for CPY removal.The combination of plants and microbes creates a natural system capable of breaking down the pesticide and reducing its harmful environmental effects.The pathway for the degradation of CPY using constructed wetlands is shown in Fig. 4, and the transformation of CPY in different compounds is demonstrated in Fig. 5.

Conclusion and future perspectives
Most conventional procedures can only transport toxins from one phase to another, which prevents the complete breakdown of organic pollutants.These results highlight the need for cutting-edge methods to remediate these toxins from the ecosystem.Nano-based removal techniques emerged as effective options for the remediation of organic contaminants.Many researchers across the world are now working on green synthesized nanomaterial for the treatment of organic toxins.It is also found to be an effective and sustainable alternative.It is high time to start exploring new and advanced methods for the treatment capable of degrading pesticides ultimately into eco-friendly compounds.On the other hand, it must be cost-effective, efficient, and green chemistry based.
CPY has been a significant hazard to the ecology with excess and unregulated use.The WHO classifies it as a hazardous pesticide.Though CPY has lower environmental durability, it is found in water, soil, sediment, crops, and vegetables all around the globe.CPY remains also found in human fluids, breast milk, urine, blood, and saliva, thereby proving the persistence of CPY in the human diet and body.Additionally, CPY biodegradation has attracted significant global attention, and several microbial and microbial enzymes have been identified and tested for their biodegradation capability (incidental metabolism).Researchers have isolated numerous CPY degradation mechanisms; however, the environmental fate of CPY and metabolites must be investigated.Also, much work is necessary to create biosensors to determine the CPY in the polluted environment.and editing; formal analysis.Mohammed Khaloofah Mola Al Mesfer: writing-formal analysis.Javed Khan Bhutto: writing-review and editing.Krishna Kumar Yadav: methodology, writing original draft, supervision.
Funding The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through a large group Research Project under grant number RGP2/192/44.
Responsible Editor: Hongwen Sun Extended author information available on the last page of the article / Published online: 27 September 2023 Environmental Science and Pollution Research (2023) 30:108347-108369

Fig. 1
Fig. 1 Fate of chlorpyrifos in the environment

Fig. 2
Fig. 2 Measures to prevent the exposure and poisoning of chlorpyrifos (Utyasheva and Bhullar 2021)

Fig. 3
Fig.3Chlorpyrifos-degradation process and its ultimate fate in the environment (Source:Islam et al. 2017)

Fig. 4
Fig. 4 Pathway for deprivation of chlorpyrifos using constructed wetlands (plant-microbial interaction); A proto-type constructed wetland and execution, B proto-type constructed wetland with indigenous bacterial strains and Canna and Mentha spps., C CPY-metabolites

Table 3
Influences of CPY and other pesticides on soil quality

Table 4
Summary of chlorpyrifos residue detection in various samples

Table 5
Remediation techniques for chlorpyrifos with their advantages and disadvantages

Table 6
Chlorpyrifos-degrading bacteria isolated from different polluted sites worldwide

Table 7
Advantages and limitations of different microorganisms used for CPY-degradation