Biogenic synthesis of gold nanoparticles by plant-growth-promoting bacteria isolated from philippine soils

Issue Date

6-2013

Abstract

Plant-growth-promoting bacteria (PGPB) and actinomycetes isolated from Philippine soils were screened for their ability to extracellularly synthesize gold nanoparticles (Au0) from ionic gold (Au3+). Sixteen isolates, which include 12 PGPBs and four actinomycetes, were tested for the presence of nitrate reductase activity. Nitrate reductase is one of the enzymes responsible in the bioreduction of ionic gold. Ten PGPBs exhibited nitrate reductase activity after 5 d of incubation at 37 °C. All the four tested actinomycetes did not exhibit the aforementioned enzyme activity. Promising PGPB isolates for gold nanoparticle synthesis were selected based on their level of nitrate reductase activity. Extracellular synthesis of gold nanoparticles was determined by incubation of the PGPB culture supernatant with gold (III) chloride trihydrate (HAuCl4·3H2O) for 7 d at 28 °C. UV/Vis scanning spectroscopy of the culture supernatants of PGPBs 1 and 5 showed absorbance peaks of gold nanoparticles at 570 nm and 541 nm, respectively. Transmission electron microscopy (TEM) of the promising PGPBs 1 and 5 showed the presence of gold nanoparticles in the 10-100 nm size range. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis confirmed the production of gold nanoparticles by PGPB 5.

Source or Periodical Title

Philippine Agricultural Scientist

ISSN

0031-7454

Volume

96

Issue

2

Page

129-136

Document Type

Article

Language

English

Subject

Electron microscopy, Gold nanoparticles, Green chemistry, Nanotechnology, Plant-growth-promoting bacteria

Digital Copy

yes

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