Ia. Minerals 2021, 11, 1175. https://doi.org/10.3390/ min11111175 Academic Editor: Sytle M. Antao Received: 2 September 2021 Accepted: 19 October 2021 Published: 22 OctoberKeywords: platinum; nanoparticles; extreme acidophiles; Fe(III)-reducing bacteria; Acidocella sp.; Acidiphilium sp.1. Introduction Metal nanoparticles (NPs) have lately gained Nitrocefin medchemexpress rising focus owing to their possible for technological innovation in many sectors, including energy, catalysis, pharmaceuticals, optics, and photonics industries. The significant specific surface region of nano-sized materials makes it possible for minimization from the metal consumption when maximizing its impact. Among other metal NPs, Pt(0)NPs are of specific significance. Their potential is extensively explored in applications such as automobiles, fuel cells, petrochemicals, electronics, nanomedicine, optics, drug delivery, and antimicrobial, antioxidant, and anticancer agents [1,2]. Moreover, the production of “green” hydrogen is gaining rising interest worldwide as an option clean energy to contribute to the decarbonization in the environment. “Green” hydrogen is made via the water electrolysis reaction, wherein Pt plays a essential function as the reaction catalyst. In spite of its importance and growing demand, Pt is defined as a vital raw material and its future supply is facing issues. Conventionally, the production of metal NPs employs multi-step physical and chemical methods applying a top-down (bulk metal is mechanically broken down to NPs) or bottom-up method (precursor metal ions are assembled to produce NPs) . Aztreonam Protocol Nevertheless, the necessity to avoid toxic chemical compounds and hazardous situations has led to an escalating interest in greener and simpler biological alternatives. So far, the biological fabrication of metal NPs explored a range of life forms, like bacteria, yeast, fungi, algae, and plants, for metal species such Au, Ag, Pd, Pt, Ni, Co, and Fe [3,4]. The size of biogenic metal NPs is usually controlled by modifying conditions like concentrations of electron donors and reaction inhibitors [5,6].Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Copyright: 2021 by the authors. Licensee MDPI, Basel, Switzerland. This short article is an open access article distributed below the terms and conditions from the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ four.0/).Minerals 2021, 11, 1175. https://doi.org/10.3390/minhttps://www.mdpi.com/journal/mineralsMinerals 2021, 11,2 ofAmong these microorganisms or plants because the template for NPs’ production, numerous bacterial species possess the ability to minimize soluble metal species to zero-valent nanometal. For the bio-Pt(0)NPs’ production, a number of bacterial species have been utilized so far, e.g., Acetobacter xylinum , Acinetobacter calcoaceticus , Desulfovibrio spp. [9,10], Escherichia coli , Shewanella spp. [12,13], Pseudomonas spp. , Streptomyces sp. , as well as a mixed consortium of sulfate-reducing bacteria  too as cyanobacteria [17,18]. Additionally to whole cells, microbial cell extracts from several bacterial species have also been investigated . Other than these, halophilic bacteria from salt lakes (Halomonadaceae, Bacillaceae, and Idiomarinaceae) had been applied for the production of Pt(0)NPs beneath acidic saline circumstances (sea salt mixture and NH4 Cl, 20-210 g/L, pH 3-7) . Nonetheless, in spite of the fact that.