The pathways of silver nanoparticles formation by Mycobacterium smegmatis

Comparison of the Wild-Type Obligate Methylotrophic Bacterium Methylophilus quaylei and its Isogenic Streptomycin-Resistant Mutant via Metal Nanoparticle Generation

“…As the source of ionic silver, an aqueous solution of Ag(NH 3 ) 2 NO 3 synthesized from AgNO 3 and ammonia according to a modified Tollens protocol was used to form the Ag°NPs [19,26]. The sterile Ag(NH 3 ) 2 NO 3 solution was added directly to the samples to achieve a final concentration of 0.1 mM.…”

“…Five microliters of the reaction mixture was transferred to the grids for transmission electron microscopy. After 5 min of sorption of the cells and NPs, the liquid was removed, and the grids were washed five times with double-distilled water and dried for 15 h. Aliquots of the samples from which the microorganisms were removed by centrifugation (10,000×g, 25 min) were used as the control [18,19]. The absence of bacteria in the centrifuged control samples was confirmed by electron microscopy and by the absence of growth on MQ and LB agar media.…”

“…In the control analogs, specifically in the corresponding water samples that were released from the bacterial cells, the generation of nanoparticles was not observed because of the absence of cation reductants in the oligotrophic medium of the samples. The authors named this method of studying the cells of microorganisms the DBNG (detection of biogenic nanoparticles generation) [18,19].…”

“…It has been proposed to use the ability of microorganisms to generate metal nanoparticles from reduced cations as an indicator of the presence of metabolically active cells in test samples [19]. Since it is known that the external components of microbial cells play the primary role in the recovery of cations [20][21][22][23], this study compared the ability of closely related analogs of cultures of microorganisms that differ in the characteristics of the surface structures of their cells to generate biogenic nanoparticles of noble metals.…”

Detection of Microorganisms in Low-Temperature Water Environments by in situ Generation of Biogenic Nanoparticles

“…Several studies have reported natural polymers (such as chitosan, proteins and amino acids, sugars, starch, and tannic acid) as reducing agents for the synthesis of metallic nanoparticles (Prakash and Sharma, 2010;Kharissova et al, 2013;Velusamy et al, 2016;Masse et al, 2019;Navarro Gallón et al, 2019). Differences in generated biogenic nanoparticles depend on the physiology of microorganisms as well as on the medium composition and conditions at their formation (Narayanan and Sakthivel, 2010;Zhang et al, 2011;Wang et al, 2012;Sorokin et al, 2013;Wu et al, 2013;Tyupa et al, 2016;Muller, 2018;Siddiqi et al, 2018). However, only metabolically active cells can rapidly (in minutes) generate metal nanoparticles from metal ions of the added salt due to their ability to constantly "efflux" electrons and electron donors into the medium (Zhou et al, 2013;Skladnev et al, 2017a;Wang et al, 2019).…”