The image displays various biowastes, important constituents, and possible products of the pretreatment process.

• Potential involvements of microbial laccases in the synthesis of silver and gold nanoparticles have been comprehensively assessed. • Treasured roles of microbes and associated enzymes in synthesis of gold and silver nanoparticles have also been presented. • As potential green biocatalysts for the synthesis of metal nanoparticles, microbial laccases may be promisingly used. • Methodologies as well as involved possible mechanisms have been discussed in details in order to disclose the effectiveness of microbial laccases in the synthesis of gold and silver nanoparticles. • Different characterization results of synthesized gold and silver nanoparticles based on UV–Vis spectra, XRD, SEM, TEM and other techniques have also been discussed. • Mechanistic evaluation also shows a hope for the effectiveness of microbial laccases in the synthesis of other metal nanoparticles.

A laccase from the culture filtrate of white rot fungus a MTCC-145 has been purified and characterized. The method involved concentration of the culture filtrate by ultrafiltration and an anion exchange chromatography on diethylaminoethyl (DEAE) cellulose. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and native polyacrylamide gel electrophoresis (native PAGE) both gave single protein bands indicating that the enzyme preparation was pure. The molecular mass of the enzyme determined from SDS-PAGE analysis was 75.0 kDa. Purification fold was 21.5 while recovery of the enzyme activity was 11.52%. Using 2,6-dimethoxyphenol, diammonium salt of 2,2'-[azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid)] and 3,5-dimethoxy-4-hydroxybenzaldehyde azine as substrates, the Km, kcat, and / values of the laccase were found to be 440 µM, 6.45 s, 1.47 × 10 M s; 366 µM, 6.45 s, 1.76 × 10 M s; and 226 µM, 6.45 s, 2.85 × 10 M s, respectively. The pH and temperature optima were 4.5 and 50°C, respectively. The enzyme was most stable at pH 5.0 when exposed for 1 h. The purified laccase has yellow color and shows no absorption band around 610 nm characteristic of blue laccases. The enzyme transforms toluene and substituted toluenes to corresponding benzaldehyde and substituted benzaldehydes in the absence of mediator molecules with higher catalytic efficiency as compared to other known laccases.