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A novel bacterial isolate Stenotrophomonas maltophilia as living factory for synthesis of gold nanoparticles.

Nangia Y, Wangoo N, Goyal N, Shekhawat G, Suri CR - Microb. Cell Fact. (2009)

Bottom Line: Gold nanoparticles were characterized and found to be of ~40 nm size.Electrophoresis, Zeta potential and FTIR measurements confirmed that the particles are capped with negatively charged phosphate groups from NADP rendering them stable in aqueous medium.The process of synthesis of well-dispersed nanoparticles using a novel microorganism isolated from the gold enriched soil sample has been reported in this study, leading to the development of an easy bioprocess for synthesis of GNPs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Microbial Technology (CSIR), Sector 39-A, Chandigarh 160036, India. raman@imtech.res.in.

ABSTRACT

Background: The synthesis of gold nanoparticles (GNPs) has received considerable attention with their potential applications in various life sciences related applications. Recently, there has been tremendous excitement in the study of nanoparticles synthesis by using some natural biological system, which has led to the development of various biomimetic approaches for the growth of advanced nanomaterials. In the present study, we have demonstrated the synthesis of gold nanoparticles by a novel bacterial strain isolated from a site near the famous gold mines in India. A promising mechanism for the biosynthesis of GNPs by this strain and their stabilization via charge capping was investigated.

Results: A bacterial isolate capable of gold nanoparticle synthesis was isolated and identified as a novel strain of Stenotrophomonas malophilia (AuRed02) based on its morphology and an analysis of its 16S rDNA gene sequence. After 8 hrs of incubation, monodisperse preparation of gold nanoparticles was obtained. Gold nanoparticles were characterized and found to be of ~40 nm size. Electrophoresis, Zeta potential and FTIR measurements confirmed that the particles are capped with negatively charged phosphate groups from NADP rendering them stable in aqueous medium.

Conclusion: The process of synthesis of well-dispersed nanoparticles using a novel microorganism isolated from the gold enriched soil sample has been reported in this study, leading to the development of an easy bioprocess for synthesis of GNPs. This is the first study in which an extensive characterization of the indigenous bacterium isolated from the actual gold enriched soil was conducted. Promising mechanism for the biosynthesis of GNPs by the strain and their stabilization via charge capping is suggested, which involves an NADPH-dependent reductase enzyme that reduces Au3+ to Au0 through electron shuttle enzymatic metal reduction process.

No MeSH data available.


Related in: MedlinePlus

(A) UV-vis spectra of GNPs synthesis by adding different concentrations of NADPH in the solution of suspended biomass along with HAuCl4 (C3 to C7) and (B) shows the GNPs synthesis by adding different concentrations of NADPH in the solution of suspended biomass along with HAuCl4 (tubes C3 to C7). In controls (C1 and C2), either cell mass (C1) or NADPH (C2) was not added.
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Figure 5: (A) UV-vis spectra of GNPs synthesis by adding different concentrations of NADPH in the solution of suspended biomass along with HAuCl4 (C3 to C7) and (B) shows the GNPs synthesis by adding different concentrations of NADPH in the solution of suspended biomass along with HAuCl4 (tubes C3 to C7). In controls (C1 and C2), either cell mass (C1) or NADPH (C2) was not added.

Mentions: In microorganisms, the possible mechanisms of resistance against metal ions usually involve biosorption, bioaccumulation, extra-cellular complexation, efflux system, alteration of solubility and toxicity via reduction or oxidation [22]. Our study suggested that the biosynthesis of GNPs and their stabilization via charge capping in Stenotrophomonas maltophilia involved NADPH-dependent reductase enzyme that converts Au3+ to Au0 through electron shuttle enzymatic metal reduction process. For further confirmation, biomass was incubated with varying concentrations of NADPH (from 0.05 mM to 0.8 mM NADPH) and change in color of solution was monitored spectrophotometrically (Fig 5a) and visually (Fig. 5b). Control experiments, without the addition of either cell free extract (C1) or cell free extract without NADPH (C2), showed no change in color of suspension. However, addition of NADPH in the cell free extract at varying concentrations (C3 to C7) showed the synthesis of GNPs with gradual increase in color intensity (Fig. 5b). This confirms the formation of GNPs only in the presence of both biomass and NADPH. Zeta potential measurements of the GNPs showed a peak at -16.7 mV (see Additional file 1, S3), suggesting capping of GNPs by negatively charged phosphate ions from NADP. Based on these experimental findings, a schematic representation of the potential mechanism of gold nanoparticles synthesis by Stenotrophomonas maltophilia through enzymatic reduction is proposed (Fig. 6). The enzyme involved in the synthesis of metal nanoparticles may be a specific reductase present in microorganism, which may be induced by the specific ions and reduced metal ions to metallic nanoparticles.


A novel bacterial isolate Stenotrophomonas maltophilia as living factory for synthesis of gold nanoparticles.

Nangia Y, Wangoo N, Goyal N, Shekhawat G, Suri CR - Microb. Cell Fact. (2009)

(A) UV-vis spectra of GNPs synthesis by adding different concentrations of NADPH in the solution of suspended biomass along with HAuCl4 (C3 to C7) and (B) shows the GNPs synthesis by adding different concentrations of NADPH in the solution of suspended biomass along with HAuCl4 (tubes C3 to C7). In controls (C1 and C2), either cell mass (C1) or NADPH (C2) was not added.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2719591&req=5

Figure 5: (A) UV-vis spectra of GNPs synthesis by adding different concentrations of NADPH in the solution of suspended biomass along with HAuCl4 (C3 to C7) and (B) shows the GNPs synthesis by adding different concentrations of NADPH in the solution of suspended biomass along with HAuCl4 (tubes C3 to C7). In controls (C1 and C2), either cell mass (C1) or NADPH (C2) was not added.
Mentions: In microorganisms, the possible mechanisms of resistance against metal ions usually involve biosorption, bioaccumulation, extra-cellular complexation, efflux system, alteration of solubility and toxicity via reduction or oxidation [22]. Our study suggested that the biosynthesis of GNPs and their stabilization via charge capping in Stenotrophomonas maltophilia involved NADPH-dependent reductase enzyme that converts Au3+ to Au0 through electron shuttle enzymatic metal reduction process. For further confirmation, biomass was incubated with varying concentrations of NADPH (from 0.05 mM to 0.8 mM NADPH) and change in color of solution was monitored spectrophotometrically (Fig 5a) and visually (Fig. 5b). Control experiments, without the addition of either cell free extract (C1) or cell free extract without NADPH (C2), showed no change in color of suspension. However, addition of NADPH in the cell free extract at varying concentrations (C3 to C7) showed the synthesis of GNPs with gradual increase in color intensity (Fig. 5b). This confirms the formation of GNPs only in the presence of both biomass and NADPH. Zeta potential measurements of the GNPs showed a peak at -16.7 mV (see Additional file 1, S3), suggesting capping of GNPs by negatively charged phosphate ions from NADP. Based on these experimental findings, a schematic representation of the potential mechanism of gold nanoparticles synthesis by Stenotrophomonas maltophilia through enzymatic reduction is proposed (Fig. 6). The enzyme involved in the synthesis of metal nanoparticles may be a specific reductase present in microorganism, which may be induced by the specific ions and reduced metal ions to metallic nanoparticles.

Bottom Line: Gold nanoparticles were characterized and found to be of ~40 nm size.Electrophoresis, Zeta potential and FTIR measurements confirmed that the particles are capped with negatively charged phosphate groups from NADP rendering them stable in aqueous medium.The process of synthesis of well-dispersed nanoparticles using a novel microorganism isolated from the gold enriched soil sample has been reported in this study, leading to the development of an easy bioprocess for synthesis of GNPs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Microbial Technology (CSIR), Sector 39-A, Chandigarh 160036, India. raman@imtech.res.in.

ABSTRACT

Background: The synthesis of gold nanoparticles (GNPs) has received considerable attention with their potential applications in various life sciences related applications. Recently, there has been tremendous excitement in the study of nanoparticles synthesis by using some natural biological system, which has led to the development of various biomimetic approaches for the growth of advanced nanomaterials. In the present study, we have demonstrated the synthesis of gold nanoparticles by a novel bacterial strain isolated from a site near the famous gold mines in India. A promising mechanism for the biosynthesis of GNPs by this strain and their stabilization via charge capping was investigated.

Results: A bacterial isolate capable of gold nanoparticle synthesis was isolated and identified as a novel strain of Stenotrophomonas malophilia (AuRed02) based on its morphology and an analysis of its 16S rDNA gene sequence. After 8 hrs of incubation, monodisperse preparation of gold nanoparticles was obtained. Gold nanoparticles were characterized and found to be of ~40 nm size. Electrophoresis, Zeta potential and FTIR measurements confirmed that the particles are capped with negatively charged phosphate groups from NADP rendering them stable in aqueous medium.

Conclusion: The process of synthesis of well-dispersed nanoparticles using a novel microorganism isolated from the gold enriched soil sample has been reported in this study, leading to the development of an easy bioprocess for synthesis of GNPs. This is the first study in which an extensive characterization of the indigenous bacterium isolated from the actual gold enriched soil was conducted. Promising mechanism for the biosynthesis of GNPs by the strain and their stabilization via charge capping is suggested, which involves an NADPH-dependent reductase enzyme that reduces Au3+ to Au0 through electron shuttle enzymatic metal reduction process.

No MeSH data available.


Related in: MedlinePlus