The excessive use of neonicotinoids has generated long-term toxic residual contamination in the environment (Shahid et al., 2021). More importantly, when various microbes convert the parent compounds, it may lead to intermediates with the same or higher toxicity than the parent compounds (Li, 2021). Consequently, a comprehensive understanding of neonicotinoid biodegradation pathways would help to better utilize these functional microbes for more sustainable remediation.

To degrade clothianidin, the breakdown of C-N bonds between thiazolyl methyl and the guanidine division delivers carbon for the transformation of clothianidin to 2 chloro-5-methyl thiazole and methyl nitroguanidine (Parte and Kharat, 2019). The microbial method slowly degraded clothianidin to ((2-chlorothiazol-5-yl) methyl-3-methylguanidine and methyl-3-(thiazol-5-yl) methyl) guanidine via denitrification and dehalogenation (Pang et al., 2020). Mori et al. (2017) studied the clothianidin’s degradation and metabolic pathways using pure culture white-rot fungus, Phanerochaete sordida, inoculated from the rotten wood. The degradation metabolite of clothianidin N-(2-chlorothiazol-5-yl-methyl)-N′-methyl urea was determined using high-resolution electrospray ionization mass spectrometry technique. Wang et al. (2019c) also reported the degradation of clothianidin. Still, the difference from the above study is the use of bacteria instead of fungi, and results revealed that this compound degraded into further three metabolites, while the one metabolite is identical in the study as mentioned above. The other two metabolites are N-(1, 3-thiazole-5-ylmethyl)- N′-methyl guanidine and 5-amino-methlthiazol. The bacterial strains used in this study (Ochrobactrum anthropi, Acinetobacter johnsonii, Pseudomonas sp., and Stenotrophomonas maltophilia) provided the highest degradation of 79.3% in the mineral salt medium after the incubation of 15 days. So, this could be due to the use of different microbial species, which give the various metabolites of the same compound (Figure 2).

Imidacloprid is highly persistent in soil with a half-life of more than 100 days (Anhalt et al., 2007). In the case of imidacloprid, oxidation and nitro reduction are the two most essential pathways (Lu et al., 2016). Imidacloprid cleavages into metabolites like urea, 6-chloronicotinic aldehyde, 6-chloro-N-methylnicotinacidamide, and 6-chloronicotinic acid (Sabourmoghaddam et al., 2015; Fusetto et al., 2017). Three main different biological degradation pathways can degrade the imidacloprid: hydroxylation of the imidazolidine ring, reduction of the nitro group, and loss of the nitro group (Figure 3). In another study for the degradation of imidacloprid, a bacterial strain Klebsiella pneumoniae strain BCH1 was isolated. After optimizing bacterial strain on various environmental conditions, results showed that it was more active at 30 °C and degraded approximately 78% of imidacloprid within a week. Moreover, in this study using gas chromatography and mass spectrometry, three metabolites were identified as nitrosoguanidine, imidacloprid guanidine and 6-chloronicotinic acid and toxicity of parent compound and their intermediates were tested using model insect silkworm (Bombyx mori) (Phugare et al., 2013). Ma et al. (2014) proposed the metabolic pathway of imidacloprid by using consortium Pseudoxanthomonas indica CGMCC 6648. In the existence of glucose, the imidacloprid can be degraded to 5-hydroxy imidacloprid and imidacloprid olefin can be degraded in 6 days. In the presence of lactose, imidacloprid can be degraded to 5-hydroxy imidacloprid in 48 h. However, in the presence of pyruvate, it can form olefin imidacloprid in 96 h. P. indica CGMCC 6648 simultaneously degraded the imidacloprid and formed olefin imidacloprid. In another study, Sharma et al. (2014a) also studied the degradation of imidacloprid by Bacillus alkalinitrilicus and proposed possible intermediates such as 6-chloronicotinic acid, nitrosimine, and imidacloprid-NTG.

The degradation of acetamiprid and its metabolic pathway was evaluated by Sun et al. (2018) using Ensifer adhaerens CGMCC 6315, which rapidly degraded 87.8% of acetamiprid-polluted soil (at the initial concentration of 5 mg/kg) within 2 days. During the microbial degradation of acetamiprid, the triple bond between carbon and nitrogen of the compound was oxidized and splintered to produce N-amidoamine derivatives. Due to the uneven breakdown, the product was divided into N-methyl-(6-chloro-3-pyridyl) methylamine and (Z)-1-ethylideneurea. The metabolites rapidly produced 6-chloronicotinic acid, which was finally mineralized to H₂O and CO₂. In another study, Shi et al. (2018) demonstrated the metabolic pathway of acetamiprid via Fusarium sp. strain. CS-3 N′-[(6-chloropyridin-3-yl) methyl]-N-methylacetamide, 2-chloro-5-hydroxymethylpyridine, and 6-chloronicotinic acid were distinguished as the most prevailing intermediates (Figure 4).

The metabolic pathway of thiacloprid was also reported. Zhang et al. (2018b) showed that at least eight bacterial genera were linked to the degradation of thiacloprid into its intermediate thiacloprid amide, which would be related to oxidative cleavage. Recently, Zhao et al. (2019b) demonstrated the transformation of thiacloprid via nitrogen-fixing bacterium Microvirga flocculans CGMCC 1.16731 through the process of hydroxylation and hydration to thiacloprid amide and 4-hydroxy thiacloprid. A cobalt-type nitrile hydratase (nhase) is formed by two subunits, such as α-subunit (tnhA) and a β-subunit (tnhB). Both subunits transformed thiacloprid to thiacloprid amide (Figure 5).

Thiamethoxam, 3-(2-chloro-1,3-thiazol-5-yl-methyl)-5-methyl-1,3,5-oxadiazinan-ylidene (nitro) amine, is another type of neonicotinoid pesticide that shares the same mechanisms as imidacloprid and has no interactive resistance to imidacloprid, idinidine, or alkenididine (Pang et al., 2020). Pandey et al. (2009) studied the microbial degradation of thiamethoxam and imidacloprid by Pseudomonas sp. 1G, and the results of the study revealed that both pesticides were transformed to nitrosoguanidine ( = N-NO), desnitro ( = NH), and urea ( = O) metabolites. In another study, a demethylation pathway was adopted to degrade thiamethoxam, forming desmethyl-thiamethoxam (Zhou et al., 2013; Figure 6).

For the biodegradation of nitenpyram and dinotefuran, Wang et al. (2019b) isolated a white-rot fungus, Phanerochaete sordida YK-624, and proposed their microbial metabolic pathways. Nitenpyram converted into their intermediate (Z)-N-((6-chloropyridin-3-yl) methyl)-N-ethyl-N′-hydroxyacetimidamide in two ways, reduction of nitenpyram and by denitrosation or deamination. In the opening ring of the hydroxyl group, by hydroxylation and dehydration pathway, dinotefuran was converted into its metabolites (Figure 7).

Nowadays, as compared to the common biological pathways, traditional and advanced molecular biological techniques such as clone libraries, probes, reverse sample genome probing, fluorescent in situ hybridization, community profiling or DNA fingerprinting, next-generation sequencing, pyrosequencing analysis, single-cell genome sequencing, and massively parallel signature sequencing provide a more significant explanation, identification of entire profile, and complete biodiversity of microbial communities (Bailón-Salas et al., 2017). Various techniques associated with enzymes, genes, and DNA of microbes such as genes (plasmids and transposons) are responsible for removing pesticides (Parween et al., 2016). The various molecular strategies which are used for the effective biodegradation of pesticides are restriction fragment length polymorphism (RFLP), dot blot, Southern blot, polymerase change reaction (PCR) amplification, subsequent analysis of bacterial rRNA genes by sequencing, preparing metagenomic libraries, denaturing gradient gel electrophoresis (DGGE), and microarrays (Sinha et al., 2009). Recently, Mori et al. (2021) had studied the degradation of various neonicotinoids by white-rot fungus, Phanerochaete chrysosporium, and identified cytochrome P450 enzyme and two major isoenzymes (CYP5037B3 and CYP5147A3) involved in the metabolism of three neonicotinoids (acetamiprid, imidacloprid, and thiacloprid). Both isoenzymes catalyzed the breakdown of the chloropyridinyl group and side chain of the three neonicotinoids by the N-dealkylation reaction pathway, resulting in the product in 6-chloro-3-pyridinemethanol and respective side chain fragments. In another study for the remediation of imidacloprid, two bacterial species (Ochrobactrum thiophenivorans and Sphingomonas melonis) were isolated from cotton cultivated agricultural soil. Several molecular techniques are used for their identification, such as DNA probes, DNA sequencing, protein synthesis, protein and gene expression analysis, nucleic acid extraction, PCR, and DGGE (Erguven and Demirci, 2021).

In order to further elucidate the molecular mechanism, the enzyme-based removal of xenobiotics is a straightforward, quick, eco-friendly, and socially acceptable approach for biodegradation in the natural environment. So, to fulfill this gap, scientists from all over the world have been working continuously to provide the most effective solution to increase environmental pollution (Sharma et al., 2018). A schematic diagram for the purification of novel enzymes by different sources has been illustrated in Figure 8. There are many enzymes that were purified by different sources which are involved in the bioremediation of neonicotinoids enlisted in Table 4.

For the bioremediation of acetamiprid in surface water, Sun et al. (2017) had used plant growth-promoting rhizobacterium, Variovorax boronicumulans CGMCC 4969, and their enzymatic mechanism was also investigated. The bacterium removed 34.7% of 2 mg/L acetamiprid over 120 h with a degradation half-life of 182 h, and the major intermediate was the amide product, (E)-N²-carbamoyl-N¹ -[(6-chloro-3-pridyl) methyl]-N¹ -methylacetamidine (IM-1-2). Gene cloning and over-expression related studies proved that a nitrile hydratase mediated acetamiprid hydration to IM-1-2. Yang H. et al. (2020) studied the enzymatic degradation pathway of acetamiprid using the Pigmentiphaga sp., facilitated by nitrile hydratase. Additionally, amidase and its encoding genes such as aceA and aceB are used for effective degradation. In general, aceB and a novel amidase showed the ability of initially hydrolyzing the C-N bond of acetamiprid to produce 1-(6-chloropyridin-3-yl)-N-methylmethanamine (IM 1-4), which achieved almost complete degradation of acetamiprid (Figure 3). In another study, Yang W. L. et al. (2020) studied the degradation of sulfoxaflor insecticide by enzymatic mechanism. A bacterium was isolated and identified as Aminobacter sp. CGMCC 1.17253 that degraded sulfoxaflor, while recombinant Escherichia coli strain protected the Aminobacter sp. CGMCC 1.17253 nitrile hydratase gene and the pure nitrile hydratase cobalt-containing with the subunits of α, β, attachment proteins, and three-dimensional homology of nitrile hydratase were obtained. The substrate specificity test of this study further explained that these enzymes play a significant role in other neonicotinoids such as acetamiprid and thiacloprid into their relative amide’s intermediates. By the hydration pathway, the bacterial strains convert sulfoxaflor into their intermediate [N-(methyl(oxido) {1- [6- (trifluoromethyl)pyridin-3-yl] ethyl}-k4-sulfanylidene) urea] (Yang et al., 2021).

Cytochrome P450s played a vital role in the metabolism of organic pollutants using rot fungi (Mori et al., 2017). Wang et al. (2019a) demonstrated the enzyme P450 (enriched by Phanerochaete chrysosporium) to degrade neonicotinoid insecticide acetamiprid effectively. After the incubation of 20 days, P. chrysosporium eliminate 21% and 51% of acetamiprid in two different media such as ligninolytic and non-ligninolytic, respectively.

Zhou L. Y. et al. (2014) previously reported that the nitrile hydratase enzyme of Ensifer meliloti CGMCC 7333 was a powerful tool to convert acetamiprid into the N-amidoamine metabolite, which is unstable and further degrade to make intermediate chlorinated pyridyl methylmethanamine compound. Fascinatingly, Ensifer meliloti CGMCC7333 was also proficient at degrading thiacloprid into the N-carbamoyl imine intermediate by using the same enzyme (Ge et al., 2014).

The biodegradation of imidacloprid using Trichoderma atroviride strain T23 and screening of transformants to achieve maximum degradation rate was investigated. REMI (restriction enzyme-mediated integration) technique was adopted for the construction of mutant strain. Plasmid pBluescript II KS-hph (4334 bp) containing hygromycin (hph) and ampicillin (amp) resistance genes was used. Finally, REMI mutants were confirmed by PCR and Southern hybridization analysis. Results revealed that total 174 transformants were developed from the wild T. atroviride strain T23. During sub-culturing, 21 colonies lost their resistance to hygromycin and the other 153 grew stably with a transformation frequency of 87.9%. The efficiency of transformants for the biodegradation of imidacloprid was investigated by the colorimetric method. Among 153 transformants, 57% of them showed maximum degradation ability compared to wild strain (He et al., 2014). For the bioremediation of acetamiprid in an agroecosystem, Wang et al. (2013a) isolated Pigmentiphaga sp. strain AAP-1 from polluted soil. The results demonstrated that bacterial strain degraded acetamiprid in soil efficiently. The bacterial community was also recovered from contaminated soil, by analysis of terminal (RFLP), after the incubation of Pigmentiphaga sp. strain AAP-1.

The biodegradation mechanism has certain limitations. It is successful at one location and may not be feasible in other places, and identifying the polluted sites is also quite time-consuming. Additionally, the mechanism that controls the growth and activity of microbial strains to degrade xenobiotics in field conditions is not well understood (Lovley, 2003). Therefore, laborious efforts are needed to make the degradation process effective, faster, quite efficient, and more suitable to act on a wide variety of organic and inorganic pollutants (Kumar Awasthi et al., 2020). By using molecular techniques to protect the environment, including genomics, transcriptomics, proteomics, and metabolomics plays a significant role in microbial habitats (Li et al., 2017).

These omics demonstrate extensive insights into the functional behavior of organisms by enhancing our knowledge of key biosynthetic processes and molecules such as genes, proteins, and metabolites. These approaches not only are used to investigate the crucial role of microbial species that regulate soil functions, enhance plant growth, and are used as a quorum sensing to understand the community composition to assign an ecological role but also provide behavioral information of cultured and uncultured microbial species and identify genes that actively participate in degradation process (Sharma et al., 2008; Festa et al., 2017; Malik et al., 2021). These omics also provide essential data about the genes and proteins involved in the degradation of pesticides and their metabolites (Rodríguez et al., 2020). Biodegradation genomics is used to identify effective genes in various microbial communities that encode specific enzymes used in biodegradation (Bharagava et al., 2019). Recently, Yang H. et al. (2020) identified novel amidase enzymes and genes from Pigmentiphaga sp. strain D-2 by using genomics tools involved in the degradation of acetamiprid. In another study, Guo et al. (2021) studied the degradation of acetamiprid by hydration pathway by Pseudaminobacter salicylatoxidans CGMCC 1.17248. Furthermore, this study explained that by gene cloning and overexpression, the identification of two different nitrile hydratase AnhA and AnhB simultaneously converted acetamiprid into {1-[(6-chloro-pyridin-3-ylmethyl)-methyl-amino]-ethylidene}-urea (IM 1-2). Proteomic analysis of microbial species provides an understanding of the protein pattern, function, interaction, and regulation (Jarnuczak et al., 2019).

The identification and physiological state of microbial communities can assist the understanding of genes that are associated with biodegradation mechanism and their regulation process (Kohl, 2020). Sun et al. (2018) identified two different NHase genes (cnhA and pnhA) by Ensifer adhaerens CGMCC 6315 to degrade acetamiprid, while proteomic analysis showed that the upregulation expression of pnhA genes improved degradation of acetamiprid ability. Transcriptomics is a prevailing tool used to assess microbial RNA expression and regulation on a whole organism level and provide an extensive collection of small regulatory non-coding RNAs (Hör et al., 2018). Recently, Wang et al. (2021) provided a novel study for assessing of neonicotinoids on neuro-2a cells by lipidomics and metabolomics, which provides the ecological risk of neonicotinoids and contributes to investigating their residues in animals and humans in the future.

However, unraveling microbial interactions in complex microbial communities is a challenging task. Adopting these multi-omic approaches in co-existence with culture-based confirmation technique efficiently explains the microbial interactions affecting the biodegradation processes. It contributed to the future application and operation of environmental bioprocesses on a knowledge-based control (Chandran et al., 2020).

Nowadays, bioinformatics and computational biology have been receiving wide attention in scientific research for the solution of biological problems. These techniques used biological principles with the fusion of mathematical, computer, and statistical principles to assist the development and application of bioremediation (Tomar, 2021). Besides the molecular and omics approaches, many online databases provide information regarding pesticide biodegradation by using microbes and their pathways (Nolte et al., 2018). The mainly used databases in the field of biodegradation are the University of Minnesota pathway prediction system (UM-PPS), microbial volatile organic compounds (mVOCs), University of Minnesota biocatalysts or biodegradation database (UM-BBD), biodegradation network molecular biology database (BioNeMo), pesticide target interaction database (PTID), microbial genome database (MBGD), biodegradative oxygenase’s database (oxdbase), and biocyc and metacyc compatible with both Windows and Linux operating system (Hou et al., 2004; Effmert et al., 2012; Arora and Bae, 2014). UMBBD pathway forecast database shows the data regarding microbial biocatalytic reactions, biodegradation pathways, and metabolites achieved during the removal of pesticides by microbes (Dvořák et al., 2017).

University of Minnesota pathway prediction system provides information about the possible intermediates of pesticides, biocides, and pharmaceuticals. Various researchers such as environmental microbiologists, risk assessors, and analytical chemists used this database and discovered most related metabolites (Wicker et al., 2010). The mVOCs database provides information about compound identification and allows quick mass spectrum comparison. Moreover, it offers new insights into the generation of microbial volatiles, which helps in various fields such as quorum sensing and medical applications (Lemfack et al., 2018). The microbial genome database plays a significant role in the inspection at the genomic level used for estimating the positions of genes, ortholog recognition, and collection of paralog data (Parks et al., 2015). The biodegradative oxygenase’s database was developed by the CSIR Institute of Microbial Technology, Chandigarh, India. This database stores information regarding oxygenase enzymes that take part in the degradation process from published literature and databases (Arora et al., 2009). Biodegradation network molecular biology databases have access to sequences barcoding for biodegradation genes and their transcription and regulation (Kumari and Kumar, 2021). For the biodegradation of thiamethoxam, a database approach was studied by Wu et al. (2021), and the biodegradation protein database including 17 sub-databases (alkb, benA, bph, bphA1, bphA2, carA, dbfA1, dxnA, dxnA-dbfA1, glx, lip, mmox, mnp, npah, ppah, ppo, and genes of P450 enzyme) was downloaded from the FunGene protein database². Besides this, the pesticide degradation gene protein database was also recovered from the NCBI protein database for eight neonicotinoid pesticides, including acetamiprid, imidacloprid, thiamethoxam, clothianidin, dinotefuran, flonicamid, clothianidin, and nitenpyram.

Immobilization is considered the most efficient technique for utilizing microbial isolates in continuous mode (Ugwuodo and Nwagu, 2020). Immobilization stops the misplacement of microbial strains during uninterrupted operation and enhances the cell density, which plays a significant role in the degradation process. Moreover, the immobilized microbes can withstand extreme environmental stress such as temperature, pH, and toxic compounds (Kurade et al., 2019). For immobilization, the support substances are vital as well as biocompatible with microbial cells and their enzymes. Different types of substances like organic (alginate, chitosan, agar, polyvinyl alcohol, collagen, cellulose, keratins, carrageenan, and chitin), inorganic (silica, alumina, iron oxides, and carbon-based materials), organic-organic hybrid, and organic-inorganic hybrid substances have been used to immobilize bacteria and other microbes (Horchani et al., 2012; Zdarta et al., 2019). Besides these substances, clay materials (bentonite, halloysite, kaolinite, montmorillonite, and sepiolite) and new support materials such as magnetic particles, mesoporous materials (zeolites, carbons, and sol-gel matrices), nanoparticles (nanogold, silver, iron, and graphene), ceramic materials (alumina, zirconia, titania, silica, iron oxide, and calcium phosphate), and electrospun materials are reported in for the immobilization of microbial cells and enzymes (Zdarta et al., 2018).

Among them, inorganic substances that have adequate mechanical strength in aggregation with synthetic or natural organic materials are more suitable for excessive biocompatibility (Wang Y. et al., 2020). There are different geometric shapes of immobilized materials such as beads (Liu et al., 2019), hollow cylinders (Lee et al., 2016), and core-shell structure beads that have been reported (Yu et al., 2019).

The immobilization technique can be done with the help of physical and chemical methods such as physical adsorption, entrapment, encapsulation, covalent bonding, and cross-linking (Wang W. et al., 2020; Figure 9). In physical adsorption, the microbial cells are attaching to the surface of the support by the poor van der Waals and via different interactions such as electrostatic, hydrophobic, and hydration, in which cells are vulnerable to the culture solution immediately (Sandhyarani, 2019).

For the process of entrapment, microbial cells are encapsulated within the polymeric matrix. Encapsulation maintained microbial strength with a semipermeable membrane capable of supplying nutrients and substrates between the carrier substances and culture media (Kumar et al., 2016). In all these methods, entrapment and encapsulation using organic or inorganic polymers is a ubiquitous method for separating bacterial cells from the growing environment (Jia et al., 2014). To remove imidacloprid residues in water, Ma et al. (2021a) synthesized a novel and efficient magnetic sludge biochar (CoFe₂O₄) with the modification of graphene oxide. Kinetics, isotherms, thermodynamics, and environmental factors analysis demonstrated that both physisorption and chemisorption were involved in the imidacloprid adsorption onto graphene oxide metal sludge biochar. The adsorption capacity of CoFe₂O₄ ensured the magnetic sensitivity of graphene oxide magnetic sludge biochar, which enabled it to be easily separated from water solution and could be used to remove the residues of imidacloprid from polluted environment. In another study, Ma et al. (2021b) adopted another way to degrade imidacloprid in water by choosing sugarcane bagasse due to its higher adsorption capacity of 313 mg/g at 298 K synthesized in potassium hydroxide and other magnetic particles (iron/zinc, Fe/Zn). There are several factors such as characterization, kinetic, isotherm, thermodynamic, and environmental factors analyzed. These factors indicated that both chemisorption and physisorption were spontaneous, endothermic, and randomly increasing processes involved in imidacloprid adsorption. Furthermore, this study demonstrated that magnetic particles easily separated from the solution, which could be reused. This study suggested that magnetic particle-based sugarcane bagasse biochar is an effective, green, and sustainable adsorbent for neonicotinoid biodegradation.

To investigate acetamiprid and silica nanoparticle transportation in pure and biochar amended sands, Wang H. et al. (2016) conducted an experiment. The results demonstrated that the retention of acetamiprid at neutral pH and less ionic strength was less in the pure sand compared to biochar amended sand. Moreover, due to their nonionic attributes, the acetamiprid cannot bond with the biochar by protonation or deprotonation, and the resulting sorption rate was not affected by environmental conditions. In another study, Gomaa et al. (2020) had immobilized Lysinobacillus macrolides strain MSR-H10 with sodium alginate for the biodegradation of acetamiprid in clay soil. The results reported that bacterial cells immobilized with sodium alginate degrade rapidly and effectively without lacking their efficiency. Recently, Dai et al. (2021) had isolated actinomycetes Rhodococcus ruber CGMCC 17550 from a nitenpyram production sewage treatment tank for surface water treatment. The cells of Rhodococcus ruber CGMCC 17550 were immobilized in calcium-alginate, which degraded nitenpyram up to 87.11% with the concentration of 100 mg/L in 8 days. By resulting the biodegradation of nitenpyram, it converts into their three metabolites by a novel hydroxylation pathway (1) (E)-1-((1-(methylamino)-2-nitrovinyl) (pyridin-3-ylmethyl) amino) ethan-1-ol, (E)-6-chloro-3-((ethyl(1-(methylamino)-2-nitrovinyl) amino) methyl) pyridin-2-ol, and (E)-(6-chloropyridin-3-yl) (ethyl(1-(methylamino)-2 nitrovinyl) amino) methanol. Further oxidation cleavage of (E)-(6-chloropyridin-3-yl) (ethyl(1-(methylamino)-2 nitrovinyl) amino) methanol converts into (E)-N-ethyl-N′-methyl-2-nitroethene-1,1-diamine (Figure 5).

Covalent binding and crosslinking are chemical methods for microbial immobilization based on covalent bonds between the functional groups present in the microbial cell wall and its support. Immobilization by the cross-linking process applies multifunctional reagents to encourage the development of a channel between functional groups on the external cell membrane (Giese et al., 2020). In covalent binding and cross-linking methods, whole microbial cells are vulnerable to chemicals and acute conditions, which may injure the cell surface and decline its metabolic activity. Therefore, crosslinking has been more victorious in the immobilization of non-viable microbial cells (Martins et al., 2013). Cross-linking has a wide range of acceptance for microbial immobilization and presents benefits like speed and simplicity compared to covalent bonding, and is challenging to control carefully (Mehrotra et al., 2021). By using covalent bonding and adsorption, Chen et al. (2019) had immobilized laccase enzyme with the support of wheat straw and peanut shells to remove nitenpyram in the agroecosystem. The results revealed that the successful application of immobilized laccase enzymes for the degradation of nitenpyram in agroecosystem has a strong and effective potential.

The half-life of the immobilized enzyme was reported to be higher than the soluble enzyme, with only a slight decrease in the catalytic activity of up to 12 consecutive cycles (Bhatt et al., 2020). The enzyme immobilization technique aims to enhance the stability of enzymes that depend on the structure, method of immobilization, and matrix material. Enzymes purified from diverse microbes can be a superior choice for large-scale pesticide biodegradation in a short time. The choice of immobilization technique in biodegradation plays a significant role with cost-effective, stable performance, good mass transfer, high intensity, long lifespan, and environment friendly (Hameed and Ismail, 2020; Celik et al., 2021).