Biosynthesis optimization of transition metal nanoparticles.

CRESPO ANDRADA KARINA, JOSÉ BARONETTI, MELISA QUINTEROS, DA SILVA M. ANGEL, PÁEZ PAULINA L, PARAJE M. GABRIELA.

Córdoba

Congreso; XI Congreso Argentino de Microbiología General (SAMIGe) 2015 - Córdoba.; 2015

Sociedad Argentina de Microbiología General

The Metal nanoparticles (Nps) havegained interest in various areas of science and technology. Microorganisms,such as bacteria and fungi, have been exploited to synthesize these particles.Nonetheless, bacteria are preferred for Nps production over eukaryoticmicroorganisms due to easy of handling and genetic manipulation.  Objective: The aim of this study wasto optimize the intra and extracellular biosynthesis (IB and EB) of iron andzinc metallic Nps using bacterial strains such us Escherichia coli and Pseudomonasaeruginosa by modifying several physical- chemical parameters.  E. coli (ATCC 25922) and P. aeruginosa(ATCC 27853) were grown in Tryptic Soy Broth (TSB) for 18 h, at 37 °C keptunder continuous agitation in an orbital shaker (200 rpm). For IB, 15 mL of thisculture were mixed with 1.5 mL of the different metallic solution [FeSO4 (II),FeCl3 (III), Fe Citrate (III)), ZnSO4 (II), ZnCl2 (II)] and incubated undershaking. Then, the solution was sonicated at 80W for 30 minutes and centrifugedat 8500 rpm for 5 min. For EB, the culture was previously centrifuged beforemixing with the saline solutions and the sonication procedure was avoided.Different conditions of salt concentration (1 and 10 mM), incubation time (24,48 and 72 h), temperature (37-50 °C) and pH (7 and 9) were assayed. Npsproduction was monitored by UV-visible in 200-800 nm range, observing thesurface plasmon resonance (SPR). For E. coli, Fe Nps were formedboth intra- and extracellularly at 1mM. However this production was not observedat 10 mM. The SPR peak was observed at 275 nm. The obtained solution presenteda dark brown color. For P. aeruginosa, iron Nps were obtained onlyextracellularly at 1mM. Nps formation was detected with Fe Citrate, FeSO4 in E.coli and FeCl3 in P. aeruginosa by increasing the pH to 9. Theincubation times were from 24 to 72 h and not significant differences wereobserved in the SPR peak. In E. coli, a peak was observed at 275 nm bothfor intra- and extracellular synthesis with ZnCl2. The solution had a whitecolor. With ZnSO4, the EB was only observed. In contrast, Zn Nps weresynthesized extracellularly with both salts in P. aeruginosa, the peakwas observed at 425nm and the solution presented a greenish-yellow color.  Conclusion: Several parameters for theFe and Zn Nps biosynthesis were optimized in E. coli and P.aeruginosa strains. The optimal conditions were obtained with P.aeruginosa at EB with FeCl3 and ZnSO4 1 mM at 37 °C for 48 h.  Future perspective: Potential biologicalactivity of biosynthesized Nps will be evaluated by determining theantimicrobial and anticoagulant activity as well asapplication of bioremediation technology to contaminatedsoil and water systems.