Bacterial synthesis of nanoparticles: A green approach

Abstract

In recent decades, the attention of scientists has been drawn towards nanoparticles (NPs) of metals and metalloids. Traditional methods for the manufacturing of NPs are now being extensively studied. However, disadvantages such as the use of toxic agents and high energy consumption associated with chemical and physical processes impede their continued use in various fields. In this article, we analyse the relevance of the use of living systems and their components for the development of "green" synthesis of nano-objects with exceptional properties and a wide range of applications. The use of nano-biotechnological methods for the synthesis of nanoparticles has the potential of large-scale application and high commercial potential. Bacteria are an extremely convenient target for green nanoparticle synthesis due to their variety and ability to adapt to different environmental conditions. Synthesis of nanoparticles by microorganisms can occur both intracellularly and extracellularly. It is known that individual bacteria are able to bind and concentrate dissolved metal ions and metalloids, thereby detoxifying their environment. There are various bacteria cellular components such as enzymes, proteins, peptides, pigments, which are involved in the formation of nanoparticles. Bio-intensive manufacturing of NPs is environmentally friendly and inexpensive and requires low energy consumption. Some biosynthetic NPs are used as heterogeneous catalysts for environmental restoration, exhibiting higher catalytic efficiency due to their stability and increased biocompatibility. Bacteria used as nanofactories can provide a new approach to the removal of metal or metalloid ions and the production of materials with unique properties. Although a wide range of NPs have been biosynthetic and their synthetic mechanisms have been proposed, some of these mechanisms are not known in detail. This review focuses on the synthesis and catalytic applications of NPs obtained using bacteria. Known mechanisms of bioreduction and prospects for the development of NPs for catalytic applications are discussed.

There is plenty of room at the plant science: A review of nanoparticles applied to plant cultures

“…The use of microorganisms in the synthesis of noble‐metals NPs, such as gold (Au) and silver (Ag), for example, usually generate spherical morphologies and in size between 10 and 50 nm. The emergence and advancement of green syntheses in relation to chemical and physical methods are environmentally friendly, economical and possibly applicable on a large scale (Duan et al, 2015; Tsekhmistrenko et al, 2020) since there is normally no need for employing high temperature, pressure, energy and toxic chemicals.…”

“…Their antioxidant and reducing properties are responsible for the reduction of metallic compounds into their respective NPs. However, several biological methods for the synthesis of NPs from microorganisms are not yet viable on an industrial scale, since aseptic conditions are necessary, and the maintenance of these environments makes it economically unfeasible (Grasso et al, 2020; Tsekhmistrenko et al, 2020). Therefore, the use of plant extracts for this purpose is potentially advantageous in relation to microorganisms because of the ease of improvement, the lower biological risk and the elaborate process of maintaining cell cultures (Burlacu, Tanase, Coman, & Berta, 2019; Jo et al, 2016; P. Singh, et al, 2016).…”

“…In addition, the wide variety of proteins and/or peptides provides an abundant reservoir for exploring the manufacture of NPs in terms of size, morphology and composition. Based on the origin of proteins and peptides, two environmentally viable syntheses, namely, microbial synthesis and phytosynthesis, are explored in the literature (Grasso et al, 2020; Tsekhmistrenko et al, 2020).…”

“…The microbial synthesis involves the use of bacteria, fungi, viruses and yeasts that are capable of producing a wide variety of NPs, intracellularly or extracellularly, and can be represented as effective bio‐factories (Grasso et al, 2020; Tsekhmistrenko et al, 2020). The use of microorganisms as reducing agents is inspired by the intrinsic prerequisite of chemical detoxification since they are used to decrease quantities of potentially toxic species (Grasso et al, 2020).…”

“…The green syntheses of NPs by microorganisms have managed to stand out and have been growing in recent years (Grasso et al, 2020; Jo et al, 2016; Tsekhmistrenko et al, 2020; C. Wang et al, 2015). Bacteria, in particular, are extremely convenient for green synthesis of NPs because of their variety and ability to adapt to different environmental conditions (Grasso et al, 2020).…”