Role of bacteria and actinobacteria in the biosynthesis of silver nanoparticles

Nanotechnology has been one the most studied areas within science and technology worldwide. The use and application of nanoparticles has increased in several applications, such as agriculture, medicine, energy, and electronics. One of the most studied and amazing nanoparticles are silver nanoparticles (AgNPs), due to their inherent antimicrobial action, which has led to their incorporation in many healthcare products, medical devices, textile products, and consumer products, such as washing machines. The synthesis of AgNPs has been reported by several physical, chemical, and biological methods. However, given the great worldwide concern for the environment, biological methods, also known as green or biogenic methods, have been extensively studied. Moreover, the green methods present several advantages over chemical and physical routes. Biological synthesis of AgNPs involves the use of macro and micro algae, fungi, plants, and bacteria or actinobacteria. Among all biological options to synthesize AgNPs, bacteria and actinobacteria are an amazing group of microorganisms that are present in many ecological niches worldwide. Moreover, given their extraordinary versatility, both bacteria and actinobacteria have been used in the biosynthesis of nanoparticles. Accordingly, this chapter highlights the main aspects related to the biosynthesis of AgNPs by bacteria and actinobacteria and their antimicrobial properties against microbial pathogens.