Potential and limitations for monitoring of pesticide biodegradation at trace concentrations in water and soil

Abstract

Pesticides application on agricultural fields results in pesticides being released into the environment, reaching soil, surface water and groundwater. Pesticides fate and transformation in the environment depend on environmental conditions as well as physical, chemical and biological degradation processes. Monitoring pesticides biodegradation in the environment is challenging, considering that traditional indicators, such as changes in pesticides concentration or identification of pesticide metabolites, are not suitable for many pesticides in anaerobic environments. Furthermore, those indicators cannot distinguish between biotic and abiotic pesticide degradation processes. For that reason, the use of molecular tools is important to monitor pesticide biodegradation-related genes or microorganisms in the environment. The development of targeted molecular (e.g., qPCR) tools, although laborious, allowed biodegradation monitoring by targeting the presence and expression of known catabolic genes of popular pesticides. Explorative molecular tools (i.e., metagenomics & metatranscriptomics), while requiring extensive data analysis, proved to have potential for screening the biodegradation potential and activity of more than one compound at the time. The application of molecular tools developed in laboratory and validated under controlled environments, face challenges when applied in the field due to the heterogeneity in pesticides distribution as well as natural environmental differences. However, for monitoring pesticides biodegradation in the field, the use of molecular tools combined with metadata is an important tool for understanding fate and transformation of the different pesticides present in the environment. Graphical abstract

Bioaugmentation has temporary effect on anaerobic pesticide biodegradation in simulated groundwater systems

“…The loss of degradation activity has been related with the lack of nutrients, which in a oligotrophic environment like groundwater may occur. Furthermore, field monitoring of pesticide degradation is in general complex, due to heterogeneously distributed pesticides, changing geochemical conditions and also lack of effective monitoring tools for field microbial communities (Aldas-Vargas et al 2022b ). Therefore, tracking inocula survival or activity might not be feasible.…”

Hazardous pollutants in agricultural soil and environment

“…Several hidden facts have been resolved since the development of emerging explorative techniques such as metagenomics. However, though it requires extensive data analysis, it justifies its potential in monitoring more than one pesticide compound at a time and analyzing their effects on the microbial community at different levels, such as class, phylum, genus, and species levels (Hou et al, 2015;Aldas-Vargas et al, 2022). The decrease in reads in the pesticide-treated soil (2G) is supported by various findings that clearly indicate the toxic nature of the pesticide (Onwona-Kwakye et al, 2020;Bhatt et al, 2021;Gangola et al, 2022d).…”

Exploring microbial diversity responses in agricultural fields: a comparative analysis under pesticide stress and non-stress conditions

“…Agricultural and natural habitats are regularly contaminated by anthropogenic activity (Jeffries et al, 2018). The application of pesticides on agricultural fields released into the environment and reaching the soil surface, different water sources, and underground water is of major concern for environmental sustainability and human health (Aldas-Vargas et al, 2022). Transformation of pesticides in the environment depends on environmental conditions and physical, chemical, and biological degradation mechanisms (Gangola et al, 2023b).…”

“…Pesticide concentration, residue, and metabolites are the traditional indicators that are not applicable for several pesticides in an anaerobic environment. Moreover, these indicators are unable to differentiate between biotic and abiotic pesticide biodegradation processes (Aldas-Vargas et al, 2022). Therefore, the use of advanced research tools is important to monitor genes involved in the biodegradation of pesticides or identify the microorganisms in the contaminated environment.…”

“…The metagenomics-based approach extends several new ways of opportunities to explore the dominant pesticide-degrading genes and their distribution in different microbial genera both in culturable and in nonculturable microorganisms within a complex environment (Fang et al, 2018). Aldas-Vargas et al (2022) used a metagenomic approach to monitor the biodegradation of pesticides. Through implementing metagenomics, the genes atzABCDEF responsible for atrazine biodegradation were identified in agricultural soil (Malla et al, 2022) and the rhizospheric region of different trees (Aguiar et al, 2020).…”