Insight into microbial synthesis of metal nanomaterials and their environmental applications: Exploration for enhanced controllable synthesis

Microbial fabrication of metal nanoparticles (MNPs) has received significant attention due to the advantages of low toxicity, energy efficiency and ecological safety. Diverse groups of MNPs can be synthesized intracellularly or extracellularly by various wild-type microorganisms, including bacteria, fungi, algae and viruses. Synthetic biology approaches, represented by genetic engineering, have been applied to overcome the shortcomings in productivity, stability, and controllability of biosynthetic MNPs. Scanning electron microscope (SEM), transmission electron microscope (TEM) and other characterization techniques assist in deciphering their unique properties. In addition, biosynthetic MNPs have been widely explored for the utilization in environmental remediation and contaminant detection. And machine learning contains a great potential for designing targeted MNPs and predicting their toxicity. This review provides a comprehensive overview of the research progress in the microbial synthesis of MNPs. An outlook on the current challenges and future prospects in the biologically controllable synthesis and engineering environmental applications of MNPs is also provided in this review.