Biological links between nanoparticle biosynthesis and stress responses in bacteria

There is rising interest in nanoparticle biosynthesis using bacteria due to the potential for applications in bioremediation, catalysis, or as antimicrobials. However, biosynthesis remains limited by the inability to control nanoparticle morphology and size due to the lack of knowledge regarding explicit molecular mechanisms. Due to their importance in nanoparticle biosynthesis and as antimicrobials, we focus our discussion on silver, gold, and copper nanoparticles. We discuss recent efforts to elucidate reduction mechanisms that have identified generic enzymes and metal resistance genes as strong candidates to facilitate nanoparticle biosynthesis. Although it is known that these enzymes and genes play significant roles in maintaining bacterial homeostasis, there are few reports discussing this topic. Thus, we discuss examples of how metal resistance genes are conserved across bacteria and have been shown to be important for both nanoparticle biosynthesis and processes such as virulence or oxidative stress responses. Overall, this review highlights biological connections between nanoparticle biosynthesis and stress responses by examining the role of reductases and metal resistance genes in both processes. This understanding provides a greater role for nanoparticle biosynthesis in bacteria and could enable a systems biology level of control over nanoparticle biosynthesis.