Towards Higher Laccase Activities Produced by Aquatic Ascomycetous Fungi Through Combination of Elicitors and an Alternative Substrate

Abstract

Laccases are versatile biocatalysts with various potential biotechnological applications, e.g. the treatment of industrial waste waters, the detoxification of environmental pollutants, or the functionalization of renewable polymeric materials. Central composition experimental design and response surface methodology was applied to optimize the production of laccase by the aquatic ascomycetous fungi, Phoma sp. UHH 5‐1‐03 and Coniothyrium sp. Kl‐S5, in shake flasks. A complex plant‐based medium (tomato juice) and two elicitors (Remazol Brilliant Blue R [RBBR] and CuSO4) were tested in combination at three concentrations. The highest laccase activity of 6322 ± 403 U/L was achieved on day 9 for Phoma sp. Coniothyrium sp. exerted a maximum laccase activity of 3035 ± 111 U/L on day 4. Optimal conditions were 30 % tomato juice and 450 mg/L RBBR for both strains. A concentration of 250 μM CuSO4 led to highest laccase activities in cultures of Coniothyrium sp., and 50 μM CuSO4 was most effective for Phoma sp. A remarkable synergistic effect of tomato juice and RBBR on laccase production was observed for both strains. The upscaling potential of the optimal induction conditions was demonstrated in a lab‐scale fermenter which resulted in maximum activities of 11030 ± 177 U/L on day 6 for Phoma sp. and 11530 ± 161 U/L on day 9 for Coniothyrium sp. This study therefore presents a promising alternative for laccase production in ascomycetes based on a cheap complex substrate in combination with two elicitors.

Stimulation of laccases from Trametes pubescens: Use in dye decolorization and cotton bleaching

“…In accordance with other reports (15)(16)(17)(18), Cu had a remarkable inducing effect on fungal enzyme synthesis, reaching up to 14 ± 3 U/ml of laccases. In addition to metal ions, aromatic compounds may stimulate laccase production (1), probably due to the presence of recognized stress responsive elements on the gene promoter (6).…”

“…as dyes) are present and affect the secondary metabolism. Even though the amplitude of the potential synergism among factors is difficult to define in advance, this phenomenon has been observed in several studies (6,18,20).…”

Enhanced production of thermostable laccases from a native strain of Pycnoporus sanguineus using central composite design

“…For the medium, the most influential parameters are carbon availability, micro-elements, the nitrogen source, and its concentration (Gochev and Krastanov, 2007). Many reports have focused on media, inducers, and operational conditions to maximize fungal laccase production (Galhaup and Haltrich, 2001;Vanhulle et al, 2007a;Junghanns et al, 2008). Some of them took costs and scalability into consideration (Osma et al, 2011).…”

“…As the carbon sources present in the medium play an important role in ligninolytic enzyme production (Eggert et al, 1996), different commercial products have been tested. Tomato-juice-based media were appropriate for cultivation of different fungal species under laboratory conditions and sufficient for laccase production (Ullrich et al, 2005;Michniewicz et al, 2006;Liers et al, 2007;Junghanns et al, 2008;Mueangtoom et al, 2010). Malt-extract and bran-flake media have been used to produce laccase specifically from Pycnoporus sanguineus (Trovaslet et al, 2007;Dantán-González et al, 2008).…”

“…Other inducers with structural similarities to lignin such as xylidine, ferulic acid, and gallic acid are often applied as they usually increase laccase activity (Bollag and Leonowicz, 1984;Pointing et al, 2000;Galhaup et al, 2002;Kunamneni et al, 2007). Because of their similarities to certain lignin structures, anthraquinone dyes such as Reactive Blue 19 and Acid Blue 62 have been tested to enhance laccase production (Junghanns et al, 2008). Soybean oil was further reported to greatly increase laccase activities in cultures of Trametes pubescens and Botryosphaeria rhodina (Dekker et al, 2007;Osma et al, 2007).…”