Statically improved fungal laccase-mediated biogenesis of silver nanoparticles with antimicrobial applications

Abstract

Green synthesis of silver nanoparticles (AgNPs) using microbial enzymes has gained great attention owing to its advantages, such as cost-effectiveness, biocompatibility, eco-friendliness, and simplicity, over conventional physical and chemical methods. In our study, the laccase enzyme of an unconventional source like the endophytic strain Alternaria arborescens MK629314 was optimized and applied for AgNP biogenesis. Alternaria arborescens laccase enzyme production was first improved using a three-factor, five-level central composite design of 20 trails; the low-cost medium of rice bran increased the laccase production to 6.5-fold. Second, the semipurified laccase enzyme was applied as a reducing and capping agent for the synthesis of AgNPs, and all the characteristics of the formed nanoparticles were studied. The applied techniques were transmission electron microscopy, UV-vis spectroscopy, Fourier transform infrared (FTIR), and dynamic light scattering (DLS). The results of all the analyses emphasized the formation of AgNPs. AgNPs biosynthesized from 25% and 50% semipurified enzyme fractions had size ranges of 6.51 ± 5.12 and 2.51 ± 3.45 nm and showed UV-characteristic peaks at wavelengths of 416 and 404 nm, respectively. DLS analysis presented good peaks with particle size means of 96.20 and 82.30 nm and zeta potentials of −58.3 and −98.5 mv. FTIR analysis showed the

Untitled

“…And then the cells were incubated at 37C o in 5 %CO 2 and 95% humidity. Cells were subcultured using trypsin 0.15 % Alharbi et al, 2020).…”

“…Most of these synthetic methods are hazardous due to application of toxic chemical agents which pose environmental problems and biological hazards (Mehndiratta et al, 2013). In recent times, much effort is being focused, by researchers, to prepare AgNPs using "green chemistry approaches", in which silver salts are biologically reduced to AgNPs using nontoxic and natural low cost polymers such as bacterial biomass (Abd El Aty and Zohair, 2020), Fungi , algae (Alharbi et al, 2020), Yeasts (Ammar et al, 2021), plant extracts (Parveen et al, 2016) and extracts of different natural gums, i.e., kondagogu-gum (Rastogi et al, 2014), salmalia malabarica gum (Murali krishna et al, 2015) guar gum Mishra 2014, Pandey andMishra, 2016), ghatti gum . These biopolymers are used as both stabilizing and reducing agents (Demchenko et al, 2020;Wang et al, 2021).…”

Diversity of Biogenic Nanoparticles Obtained by the Fungi-Mediated Synthesis: A Review

“…It has been found that laccase [ 146 , 230 , 231 , 232 ], Mn-peroxidase [ 146 ], tyrosinase [ 146 ] and ligninase [ 231 ] are involved in AuNP biosynthesis by fungi. Nitrate reductase [ 233 ], laccase [ 234 , 235 ] and xylanase [ 48 ] are involved in the AgNP mycosynthesis, while PtNP synthesis is catalyzed by hydrogenase [ 159 , 160 ]. The same culture can produce several enzymes catalyzing nanoparticle fabrication; for example, for P. chrysosporium , laccase and ligninase have been shown to be responsible for the extracellular and intracellular AuNP formation, respectively [ 231 ].…”