Lignin peroxidase mediated silver nanoparticle synthesis in Acinetobacter sp

Area of Science:

• Biotechnology
• Environmental Science
• Microbiology

Background:

• Bacteria develop resistance to environmental metals through mechanisms like transforming metal ions into nanoparticles.
• Enzymes and proteins are implicated in the biosynthesis of silver nanoparticles (AgNPs) by bacteria.

Purpose of the Study:

• To purify lignin peroxidase from Acinetobacter sp.
• To investigate the role of purified lignin peroxidase in the synthesis of silver nanoparticles (AgNPs).

Main Methods:

• Purification of lignin peroxidase using diethylaminoethyl cellulose ion exchange and Biogel P-150 gel filtration chromatography.
• Characterization of the purified enzyme using native and SDS-PAGE.
• Synthesis of AgNPs using the purified enzyme and analysis via transmission electron microscopy.

Main Results:

• A 6.5-fold purification of lignin peroxidase with a specific activity of 1.571 U/mg was achieved.
• The purified enzyme is a tetramer (99 kDa) composed of two polypeptide subunits (23.9 and 24.6 kDa).
• Spherical, polydispersed AgNPs (~50 nm) were synthesized extracellularly upon exposure to the purified enzyme.

Conclusions:

• This is the first report demonstrating the reduction of extracellular silver ions to AgNPs by lignin peroxidase from Acinetobacter sp.
• Lignin peroxidase plays a significant role in the microbial synthesis of silver nanoparticles.