Ecotoxicological test based on inhibition of fungal laccase activity: Application to agrochemicals and the monitoring of pesticide degradation processes

Deep degradation of atrazine in water using co-immobilized laccase-1-hydroxybenzotriazole-Pd as composite biocatalyst

The efficient and green removal technology of refractory organics such as atrazine in water has been an important topic of research in water treatment. A novel membrane composite biocatalyst Lac-HBT-Pd/BC as prepared for the first time by co-immobilizing laccase, mediator 1-hydroxybenzotriazole (HBT) and metal Pd on functionalized bacterial cellulose (BC) to investigate the removal of atrazine and degradation of its intermediates under mild ambient conditions. It was found that atrazine could be completely degraded in 5 h by the catalysis of Lac-HBT-Pd/BC, and the removal rate of degradation intermediates from atrazine was about 85% after continuous catalysis, which achieved deep degradation of atrazine. The effect of electrochemical activity and radical stability of the membrane composite biocatalysts loaded with Pd was investigated. The possible degradation pathways were proposed by identifying and analyzing the deep degradation products of atrazine. The Lac-HBT-Pd/BC demonstrated deep degradation of atrazine and favorable reusability as well as considerable adaptability to various water qualities. This work provides an important reference for preparing new kinds of biocatalysts to degrade refractory organic pollutants in water.

Fungal treatment of agricultural washing wastewater: Comparison between two operational strategies

Agricultural washing wastewater (AWW) is an important source of pesticides that, given its intrinsic characteristics, has a high potential to be treated by fungal bioremediation using white rot fungi. In the present study, two AWW treatment strategies were compared: a fluidized-bed reactor (FBR) with T. versicolor pellets and a rotating drum bioreactor (RDB) with T. versicolor immobilized on wood. The RDB effluent showed better results in all studied parameters compared to those of the FBR, including pesticide removal (87%), toxicity, laccase activity, COD, absorbance and microbial communities. Additionally, the fungal assemblage showed that T. versicolor was successfully immobilized in the RDB, which triggered a major shift in the initial community. Afterwards, solid by-products were treated in a fungal biopile-like system reaching high biodegradation rates. Therefore, this study validates the fungal RDB as a viable alternative for AWW treatment, opening up the possibility of a further in-situ and full-scale application.

Fungal bioassays for environmental monitoring

Environmental pollutants are today a major concern and an intensely discussed topic on the global agenda for sustainable development. They include a wide range of organic compounds, such as pharmaceutical waste, pesticides, plastics, and volatile organic compounds that can be found in air, soil, water bodies, sewage, and industrial wastewater. In addition to impacting fauna, flora, and fungi, skin absorption, inhalation, and ingestion of some pollutants can also negatively affect human health. Fungi play a crucial role in the decomposition and cycle of natural and synthetic substances. They exhibit a variety of growth, metabolic, morphological, and reproductive strategies and can be found in association with animals, plants, algae, and cyanobacteria. There are fungal strains that occur naturally in soil, sediment, and water that have inherent abilities to survive with contaminants, making the organism important for bioassay applications. In this context, we reviewed the applications of fungal-based bioassays as a versatile tool for environmental monitoring.

Microbial adaptation and impact into the pesticide's degradation

The imprudent use of agrochemicals to control agriculture and household pests is unsafe for the environment. Hence, to protect the environment and diversity of living organisms, the degradation of pesticides has received widespread attention. There are different physical, chemical, and biological methods used to remediate pesticides in contaminated sites. Compared to other methods, biological approaches and their associated techniques are more effective, less expensive and eco-friendly. Microbes secrete several enzymes that can attach pesticides, break down organic compounds, and then convert toxic substances into carbon and water. Thus, there is a lack of knowledge regarding the functional genes and genomic potential of microbial species for the removal of emerging pollutants. Here we address the knowledge gaps by highlighting systematic biology and their role in adaptation of microbial species from agricultural soils with a history of pesticide usage and profiling shifts in functional genes and microbial taxa abundance. Moreover, by co-metabolism, the microbial species fulfill their nutritional requirements and perform more efficiently than single microbial-free cells. But in an open environment, free cells of microbes are not much prominent in the degradation process due to environmental conditions, incompatibilities with mechanical equipment and difficulties associated with evenly distributing inoculum through the agroecosystem. This review highlights emerging techniques involving the removal of pesticides in a field-scale environment like immobilization, biobed, biocomposites, biochar, biofilms, and bioreactors. In these techniques, different microbial cells, enzymes, natural fibers, and strains are used for the effective biodegradation of xenobiotic pesticides.

Recent Progress and Prospects in Catalytic Water Treatment

Presently, conventional technologies in water treatment are not efficient enough to completely mineralize refractory water contaminants. In this context, the implementation of catalytic processes could be an alternative. Despite the advantages provided in terms of kinetics of transformation, selectivity, and energy saving, numerous attempts have not yet led to implementation at an industrial scale. This review examines investigations at different scales for which controversies and limitations must be solved to bridge the gap between fundamentals and practical developments. Particular attention has been paid to the development of solar-driven catalytic technologies and some other emerging processes, such as microwave assisted catalysis, plasma-catalytic processes, or biocatalytic remediation, taking into account their specific advantages and the drawbacks. Challenges for which a better understanding related to the complexity of the systems and the coexistence of various solid-liquid-gas interfaces have been identified.