Microbial innovation can solve chemical pollution

Bioremediation refers to the process by which complex pesticide molecules or compounds are converted into simple products in three ways: natural attenuation, bioaugmentation, and biostimulation 162. It also converts pesticides into non-harmful products via microorganisms during bioremediation as an eco-friendly approach for the remediation of pesticides from polluted areas 163. This process also remediates through bio-augmentation, in which exogenous organisms are supplemented to contaminated sites, which is used to improve the degradation of contaminated soil with pesticides when there is a low bioavailability of microorganisms in the local market. In contrast, appropriate conditions and nutrients are supplied during biostimulation to grow locally available microbes to metabolically stimulate activities that would facilitate the faster degradation of soil contaminated with pesticides 164. Moreover, it enhances the efficiency of pesticide degradation in the environment by modifying enzyme inducers and co-metabolic substrates 23. Table 5 shows various types of microbial strains that can degrade pesticides in contaminated soil.

These microorganisms produce specific enzymes that degrade pesticides of a simple chemical nature and use them as food or energy sources. However, pesticides composed of higher aromatics and chlorinated organic compounds are chemically inert and fail to be degraded by natural microorganisms 165. This has opened a new chapter for introducing genetically engineered microorganisms to degrade pesticides and decrease their impact on the soil environment. Over the past few decades, much research has been conducted to degrade chemical pesticides using genetically engineered microorganisms constructed using recombinant deoxyribonucleic acid (DNA) technology 166-169. However, utilization of such microorganisms for the degradation of pesticides is often hindered by the movement of genes from genetically engineered microorganisms to others, which can significantly impact the growth and distribution of indigenous microbial populations 169. Thus, more research is needed to develop a system that tracks the survival control of genetically engineered microorganisms and their release into agricultural fields.

Phytoremediation is an appropriate practical approach for the remediation of all types of soil contaminated with pesticides in the plant rhizosphere 170-171. However, it is slow compared to other processes. However, amendments with plant residues, manure, compost, organic carbon, and nutrients have been found to improve the process efficiency. They have been successfully employed to decontaminate soils and facilitate faster degradation of pesticides. However, a greater understanding of pesticides and soil-plant dynamics is needed to develop a practical low-cost phytoremediation approach 170, 172.