Towards the next decade for research on the environmental impact of nanoscale zerovalent iron on microorganisms

Nanoscale zerovalent iron (NZVI) is among the most widely used nanomaterials in environmental applications. With such an increased use of NZVI, there is a need to understand its potential impact on microorganisms, vital components of various ecosystems. Significant progress has been made in elucidating the molecular mechanisms underlying NZVI toxicity in model bacteria, while recent research has shifted toward evaluating its long-term impacts on environmental microbial systems. Herein, we first revisit a range of studies on NZVI-single microorganism interactions under aerobic and anaerobic conditions in an effort to make general conclusions regarding the NZVI toxicity mechanism at the cellular level. Additionally, a comprehensive overview is provided on the effects of NZVI on complex bacterial consortia in natural aquatic and soil environments, as well as in wastewater treatment systems. Finally, we discuss future research directions for sustainable and environmentally friendly application of NZVI.