Silver Nanoparticle Production by the Cyanobacterium Cyanothece sp.: De Novo Manipulation of Nano-Biosynthesis by Phytohormones

Abstract

Background: Numerous cyanobacteria have the potential to reduce metallic ions to form pure metal nanoparticles in a green biosynthesis process. Aim: To investigate the production capacity of silver nanoparticles by the cyanobacterium Cyanothece sp. and to examine the effect of five different phytohormones, indole acetic acid, kinetin; gibberellic acid; abscisic acid; and methyl jasmonate, on this capacity. Methods: The cyanobacterial strain was grown for 60 days and the harvested cyanobacterium biomass was incubated with 0.1 mM of AgNO3. Percentage conversion of Ag+ to Ag0 was calculated to indicate the AgNPs’ production capacity. Different concentrations of the five phytohormones were added to cultures and the AgNP production was monitored throughout different time intervals. Results: Cyanothece sp. biosynthesized spherical AgNPs (diameter range 70 to 140 nm, average diameter 84.37 nm). The addition of indole acetic acid and kinetin provoked the maximum conversion (87.29% and 55.16%, respectively) of Ag+ to Ag0, exceeding or slightly below that of the control (56%). Gibberellic and abscisic acids failed to elevate the Ag+ to Ag0 conversion rate (45.23% and 47.95%, respectively) above that of the control. Methyl jasmonate increased the Ag+ to Ag0 conversion rate to 90.29%, although nearly all the cyanobacterial cultures died at the end. Conclusion: Phytohormones could be used to induce or inhibit the green production of AgNPs with the cyanobacterium Cyanothece sp. This novel manipulation technique may have several applications in agriculture or biomedicine.

Differential Antimicrobial Effect of Three-Sized Biogenic Silver Nanoparticles as Broad-Spectrum Antibacterial Agents against Plant Pathogens

“…The three samples of biogenic nanosilver showed a strong absorbance peak at 450 nm (Figure 3 and Supplementary Materials, Figures S1 and S2). This is within the range of plasmon resonance that is characteristic of silver nanoparticles [3]. The characteristic plasmon resonance of silver nanoparticles is due to the vibrational modes of electrons based on the size and shape of nanoparticles [17].…”

“…Nanoparticles are minute particles of size 10 −9 m whose chemical and physical characteristics are different from bulk particles [1]. Cyanobacteria are wide-spread photosynthetic prokaryotes that represent bio-factories for the production of nanoparticles [2,3]. Cyanobacteria grow rapidly in inexpensive growth media, require only minerals and light energy for growth and can produce nanoparticles without toxic byproducts or energy consumption [4,5].…”

“…They are reported to reduce silver ions via chemical entities or reductase enzymes such as NADH-dependent reductases and electron carriers such as quinones [6]. The shape and size of the nanoparticles vary according to the synthetic methods, reductant, and biological source [3,7]. Hong et al [8] used the microwave-assisted method for the preparation of three different shapes of silver 2 of 13 nanoparticles: nanocubes, nanospheres, and nanowires.…”

Nanomaterials as an alternative to increase plant resistance to abiotic stresses

“…Finally, as phytohormones regulates different plant processes, novel research has proposed the implementation of these compounds to increase the efficiency in the process of NPs biosynthesis. For example ( Mohamed et al., 2022 ), found that the addition of indole acetic acid and kinetin to the cyanobacterium Cyanothece sp provoked a maximum conversion (87.29% and 55.16%, respectively) for the production of Ag NPs, and that methyl jasmonate increased the NPs conversion rate to 90.29%, although nearly all the cyanobacterial cultures died at the end. Although the effect of various nanoparticles on plant growth and development has been extensively investigated, there are still many questions about their action.…”