Biogenic selenium nanoparticles with biotechnological applications

APARICIO, FRANCISCA; SEPÚLVEDA, ROMINA; ZAPATA, CLAUDIA; TRONCOSO, OSCAR; PESCUMA, MICAELA; GONZALEZ, MÓNICA CRISTINA; ORDOÑEZ, OMAR

Congreso; XVIII Congreso SAMIGE 2013; 2023

Microbial communities capable of resisting and biotransforming selenite salts intoselenium nanoparticles (SeNPs) remain largely unexplored in Argentinean soils. This studyaimed to investigate SeNPs production by rhizosphere bacteria (isolated from two siteswithin Los Alerces National Park, Chubut) and to analyze the SeNPs antifungal activity.Prospecting across different locations led to the screening and isolation of variousbacterial strains exhibiting varying degrees of tolerance to increasing concentrations ofsodium selenite, reaching up to 640 ppm. Twelve strains capable of withstanding highconcentrations of sodium selenite while producing SeNPs were selected. The strain whichshowed the best results of selenite removal was selected for further analysis. The biogenicSeNPs produced when 100 mg/L of selenite was added (optimal Se concentrationdetermined spectrophotometrically and confirmed by ICP-MS) by B4 were isolated from theculture media and characterized using various techniques to elucidate their surfacechemistry properties. Dynamic Light Scattering (DLS) analysis determined the averagehydrodynamic diameter to be 174±13 nm for B4, nanoparticles exhibited a negative surfacecharge of -13.5 eV. Using attenuated total reflectance Fourier transform infraredspectroscopy (ATR-FTIR), organic functional groups present on the surface of thenanoparticles, coming from lipids, carbohydrates, and proteins, were identified.The effect of B4-SeNPs on fungi growth inhibition was analyzed using two species thataffect sawn timber: Olligoporus pelliculosus and Ophiostoma peregrinum. The former is awood-rotting fungus that attacks Lenga wood, while the latter is a staining fungus that affectsPinewood; both were sourced from the CIEFAP collection. Inhibition tests were conductedon both agar plates and wood samples. After 21 days of culture, the inhibitory halo wasmeasured through direct observation. Subsequent DNA extraction and molecularidentification of bacteria revealed that B4 belonged to the Bacillus genus. B4-SeNPs wereable to retard the growth of both fungi strains on agar plates and embedded wood samples.Moreover, on both wood samples lower hyphae density was observed. Furthermore, in thewood samples treated with toluidine blue, no structure damage was observed while whentreated with phloxin no hyphae were detected inside the Lenga wood samples.These results are promising, as they suggest that treatments could be developed frombacteria isolated from Patagonian soils to preserve the wood of two economically significantspecies in the region from the attacks of common pathogenic fungi. The potential applicationof biogenic SeNPs in wood protection opens new avenues for sustainable andenvironmentally friendly strategies in the timber industry.