Effects of different wavelengths of light on lignin peroxidase production by the white-rot fungi Phanerochaete chrysosporium grown in submerged cultures David A. Ramírez a,b , Sandra V. Muñoz a , Lucia Atehortua b , Frederick C. Michel Jr. a, * a Department of Food, Agricultural and Biological Engineering, The Ohio State University, 1680 Madison Ave, Wooster, OH 44691, USA b Plant, Fungi and Microalgae Biotechnology Laboratory, Universidad de Antioquia, A.A. 1226 Medellin, Colombia article info Article history: Received 21 December 2009 Received in revised form 25 June 2010 Accepted 29 June 2010 Available online 22 July 2010 Keywords: Phanerochaete chrysosporium Lignin peroxidase Visible light wavelengths Submerged cultures abstract In this study, the effects of different wavelengths of light (UV, blue, green, yellow, red) and white light on lignin peroxidase (LiP), protein, biomass and exo-polysaccharide production and glucose uptake by Phan- erochaete chrysosporium BKM-F-1767 were determined. The experiments were conducted under aerated (CS) and oxygenated (RS) culture conditions. The results showed that only green light significantly increased maximum LiP production (by 20% and 27% in CS and RS cultures respectively). Green light also increased biomass production in oxygenated cultures (RS). Blue and UV light both significantly reduced maximum LiP activity. Yellow, red and white lights had mixed effects on culture properties. This is the first time that the effects of different wavelengths of light on lignin peroxidase production and other cul- ture properties have been investigated. The novel findings may be important in improving the yield of lignin modifying enzymes for biomass conversion processes and understanding their regulation. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Light is an abiotic factor that regulates fundamental processes not only in phototrophs, but in a wide variety of organisms includ- ing fungi. While light is an essential requirement for photosynthe- sis in higher plants, it also stimulates morphogenesis in both photosynthetic and non-photosynthetic organisms (Ambra et al., 2004). Recent reports have shown that light and especially specific wavelengths of light can influence growth, secondary metabolism and the production of metabolites by fungi (Arjona et al., 2009; Corrochano, 2007; Poyedinok et al., 2008; Zapata et al., 2009). Light-mediated responses include induction of changes in mem- brane potential, gene expression, protein phosphorylation, induc- tion of protoperithecia, sexual or asexual development, entrainment of the circadian clock, conidiation, photoperiodism, secondary metabolism and carotene synthesis (Corrochano, 2007; Herrera-Estrella and Horwitz, 2007; Idnurm and Heitman, 2005). It is also well documented that different parts of the light spectrum modulate different aspects of fungal development and behavior. Fungi sense not only different qualities of light but also different intensities of light and are capable of sensing light over a broad spectrum, from ultraviolet (UV) to far-red light. The range of per- ceptible light intensities covers more than ten orders of magnitude, from gloomy starlight to full sunshine (Idnurm and Heitman, 2005). Phanerochaete chrysosporium is a filamentous basidiomycete white rot fungus that participates in the degradation process of complex woody materials (Burdsall, 1998). This fungus is the sub- ject of many investigations due to its ability to mineralize lignin and other related molecules (Michel et al., 1991; Reddy, 1995). It has great potential in many biotechnological industrial applica- tions including: the treatment of hazardous waste and the biore- mediation of contaminated soils (Alam et al., 2009), biofuel production (Shrestha et al., 2008), biopulping (Chen et al., 2002), biobleaching (Mittar et al., 1992), among others. These uses are possible because of its ligninolytic system, composed mainly of a group of extra-cellular heme-peroxidases that includes lignin per- oxidases (LiP) secreted in response to nutrient limitation during secondary metabolism (Kirk et al., 1990) and manganese-depen- dent peroxidases (MnP) (Kuwahara et al., 1984). The major en- zymes acting directly or indirectly on lignin are the lignin peroxidases (LiP) (EC 1.11.1.14), manganese peroxidases (MnP) (EC 1.11.1.13) and laccases (EC 1.10.3.2). LiPs are powerful oxi- dants as compared to typical peroxidases that can oxidize not only phenols and aromatic amines, but also a variety of other aromatic ethers and polycyclic aromatics with appropriate ionization poten- tials (Kirk and Farrell, 1987; Sanchez, 2009). A number of methods for lignin peroxidase production have been used previously, including growing the fungi in rotating bio- logical contactors (Kirk et al., 1986), in rotating drums (Paszczynski et al., 1986), immobilized in gels (Linko et al., 1986), in stirred tank reactors (Michel, 1988) and sponges of nylon (Couto et al., 2002). However, in most studies and for small scale routine production 0960-8524/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2010.06.114 * Corresponding author. Tel.: +1 330 263 3859; fax: +1 330 263 3670. E-mail address: michel.36@osu.edu (F.C. Michel). Bioresource Technology 101 (2010) 9213–9220 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech