348
N. B. Raj et al.
The first report of the synthesis of AuNPs was documented by Mukherjee et al.
(2002), whereby oxidoreductase enzyme mediated extracellular synthesis of AuNPs
in F. oxysporum. Nevertheless, the same process mechanism was not observed in
F. moniliforme. In Rhodopseudomonas capsulata, NADH-dependent reductases are
involved in AuNPs synthesis. In Phanerochaete chrysosporium, extracellular and
intracellular AuNPs were synthesized by lignolytic enzymes and proteins (Sanghi
et al. 2011).
2.1.2 Factors Affecting the Synthesis of Microbial Nanoparticles
A plethora of known parameters are reported to affect the microbial-mediated
synthesis of nanoparticles (Fig. 2). Factors such as pH, temperature, agitation rate,
incubation time, enzymes, metal ion concentration, inoculum age and biomass
concentration influence the synthesis, monodispersity and application in microbialbased nanoparticles. Some of the important factors that affect nanoparticle biosynthesis are hereby described.
Fig. 2 Factors influencing
microbial nanoparticle
synthesis