Enzymes for microplastic-free agricultural soils

Abstract

Plastic mulch films and biofertilizers (processed sewage sludge, compost or manure) have helped to increase crop yields. However, there is increasing evidence that these practices significantly contribute to microplastic contamination in agricultural soils, affecting biodiversity and soil health. Here, we draw attention to the use of hydrolase enzymes that depolymerize polyester-based plastics as a bioremediation technique for agricultural soils (in situ), biofertilizers and irrigation water (ex situ), and discuss the need for fully biodegradable plastic mulches. We also highlight the need for ecotoxicological assessment of the proposed approach and its effects on different soil organisms. Enzymes should be optimized to work effectively and efficiently under the conditions found in natural soils (typically, moist solids at an ambient temperature with low salinity). Such optimization is also necessary to ensure that already distressed ecosystems are not disrupted any further.

Keywords: Ecotoxicity; Enzymatic depolymerization; Microplastics; PETase; Plastic biodegradation; Soil bioremediation.