Induction of laccases in Trametes versicolor by aqueous wood extracts

Abstract

The induction of laccase isoforms in Trametes versicolor HEMIM-9 by aqueous extracts (AE) from softwood and hardwood was studied. Samples of sawdust of Pinus sp., Cedrela sp., and Quercus sp. were boiled in water to obtain AE. Different volumes of each AE were added to fungal cultures to determine the amount of AE needed for the induction experiments. Laccase activity was assayed every 24 h for 15 days. The addition of each AE (50 to 150 μl) to the fungal cultures increased laccase production compared to the control (0.42 ± 0.01 U ml(-1)). The highest laccase activities detected were 1.92 ± 0.15 U ml(-1) (pine), 1.87 ± 0.26 U ml(-1) (cedar), and 1.56 ± 0.34 U ml(-1) (oak); laccase productivities were also significantly increased. Larger volumes of any AE inhibited mycelial growth. Electrophoretic analysis revealed two laccase bands (lcc1 and lcc2) for all the treatments. However, when lcc2 was analyzed by isoelectric focusing, inducer-dependent isoform patterns composed of three (pine AE), four (oak AE), and six laccase bands (cedar AE) were observed. Thus, AE from softwood and hardwood had induction effects in T. versicolor HEMIM-9, as indicated by the increase in laccase activity and different isoform patterns. All of the enzymatic extracts were able to decolorize the dye Orange II. Dye decolorization was mainly influenced by pH. The optimum pH for decolorization was pH 5 (85%), followed by pH 7 (50%) and pH 3 (15%). No significant differences in the dye decolorizing capacity were detected between the control and the differentially induced laccase extracts (oak, pine and cedar). This could be due to the catalytic activities of isoforms with pI 5.4 and 5.8, which were detected under all induction conditions.

Pleurotus ostreatuslaccase recovery from residual compost using aqueous two-phase systems

“…Samples were loaded into the wells and run at 80 V for 1 h. Laccase activity was detected by reaction with 1 mmol L −1 2,6‐dimethoxyphenol (2,6‐DMP) dissolved in 100 mmol L −1 sodium acetate buffer (pH 5). The pre‐stained SDS‐PAGE standards broad range Bio‐Rad was used as the molecular weight marker standard …”

Upgrading Laccase Production and Biochemical Properties: Strategies and Challenges

“…One of the advantages for the industrial application of laccases is that their natural diversity is vast. Several laccase isoforms have been detected in many fungal species from different genera including Trametes , Pleurotus , Lentinula, Pycnoporus, Agaricus, and Phanerochaete . The genes that codify for these isoforms are differentially regulated and can be constitutively expressed or induced during the cellular life .…”

“…In the last few decades, different strategies that result in an increase in laccase productivity and improvement of their biochemical properties have been evaluated. In this context, the identification of inducers and the mechanisms implied in the regulation of gene expression is essential for the increase in laccase production in fungi . Laccase induction has been seen by many as a simple and a straight forward process (added inducer = higher laccase production), however, the exact mechanisms underlying laccase regulation are still not well understood.…”

“…Several laccase isoforms have been detected in many fungal species from different genera including Trametes, Pleurotus, Lentinula, Pycnoporus, Agaricus, and Phanerochaete. [12][13][14][15] The genes that codify for these isoforms are differentially regulated and can be constitutively expressed or induced during the cellular life. 16,17 The expression of these isoforms depends on multiple factors such as fungal growth phase, age of the culture, substrate used, the presence of inducers and conditions of the production process.…”

“…In this context, the identification of inducers and the mechanisms implied in the regulation of gene expression is essential for the increase in laccase production in fungi. 15 Laccase induction has been seen by many as a simple and a straight forward process (added inducer 5 higher laccase production), however, the exact mechanisms underlying laccase regulation are still not well understood. There have been many attempts to understand laccase induction since the 90s.…”