Abstract
This study reports the multi-step mutagenesis of Lentinus edodes towards optimization of the production of laccase and novel application of laccase in the biosynthesis of silver nanoparticles (AgNPs) which could be used to develop an eco-friendly method for the rapid biosynthesis of AgNPs. The wild strain of L. edodes was subjected to UV irradiation at 254 nm and the resultant viable mutant was further treated with acridine orange, a chemical mutagen. The strains were evaluated for the production of laccase and the crude laccase of the UV mutant (UV10) was used for the green synthesis of AgNPs. The particles were characterized by UV-Visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Laccase activities of wild, UV10 and UV10ACR8 strains of L. edodes were obtained as 2.6, 10.6 and 2.8 U/ml/min respectively after 7 days of fermentation, showing laccase yield improvement of 4.08-fold for UV10 mutant. UV-Visible spectroscopy indicated the formation of AgNPs at absorption band of 430 nm. FTIR result indicated that proteins were responsible for AgNP synthesis, while SEM analysis confirmed the formation of walnut-shaped nanoparticles with size range of 50-100 nm. The biosynthesized nanoparticles revealed effective inhibition against clinical isolates of Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae. To the best of the authors’ knowledge, this result represents the first report on the biosynthesis of AgNPs using L. edodes metabolite. The report adds to the growing relevance of L. edodes as potential industrially viable organism, used for diverse biotechnological applications.
Highlights
Nanobiotechnology is defined as the aspect of biotechnology that deals with synthesis, design and stabilization of various nanoparticles using biological tools (Shaligram et al, 2009; Lateef et al, 2015a)
Effect of mutagenesis on laccase production by the wild, UV10 and UV10ACR8 strains of L. edodes
UV10 and UV10ACR8 strains of L. edodes were recorded as 2.6, 10.6 and 2.8 U/ml/min respectively, after 7 days of fermentation (Table 1)
Summary
Nanobiotechnology is defined as the aspect of biotechnology that deals with synthesis, design and stabilization of various nanoparticles using biological tools (Shaligram et al, 2009; Lateef et al, 2015a). Nanoparticles have been classically produced by physical and chemical methods (Guzman et al, 2012) involving techniques like heating (Huang and Yang, 2004) and irradiation (Abid et al, 2002; Gasaymeh et al, 2010) These methods are costly, toxic and hazardous (Mohamed, 2013; Lateef et al, 2015a), the need for alternative, eco-friendly approaches, which may be assured by biological methods. Green synthesis of AgNPs using diverse biological materials such as spider cobweb, Cola nitida (Kolanut) seed, seed shell, pod and cell-free extract of Bacillus safensis with potent biological activities was recently demonstrated (Lateef et al, 2015b,c)
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