ORIGINAL ARTICLE Effect of different cultivation conditions and inducers on the production of laccase by the litter-dwelling fungal isolate Fusarium incarnatum LD-3 under solid substrate fermentation Urvish Chhaya & Akshaya Gupte Received: 12 October 2011 / Accepted: 10 April 2012 / Published online: 25 May 2012 # Springer-Verlag and the University of Milan 2012 Abstract The litter-dwelling fungus Fusarium incarnatum LD-3 has been identified as a novel producer of laccase. The present work was oriented towards the optimization of var- ious cultivation conditions for maximizing laccase produc- tion under solid substrate fermentation. The process parameters were optimized by the “one factor at a time” approach. Maximum laccsase production was obtained at pH 5.0 and at a temperature of 28 °C with 60 % moisture content using rice bran as a substrate. The laccase produc- tion was enhanced in the presence of aromatic inducer, i.e. ortho-dianisidine at a concentration of 0.5 mM. Laccase production was further increased by 52.56 % when the medium was supplemented with 2 % (v/v) alcohol. Among the various amino acids tested as a growth factor and nitro- gen source, D-Serine and DL-2 Amino n-butyric acid, DL- Alanine and L-Glycine were found to be the most suitable for laccase production. The highest laccase production (1,352.64 U/g) was achieved under optimized conditions, and was 2.1-fold higher than the unoptimized conditions. Thus, the novel litter-dwelling fungal isolate Fusarium incarnatum LD-3 seems to be an efficient producer of lac- case and can be further exploited for biotechnological appli- cations. This is the first report on the optimization of cultivation conditions and inducers for laccase production from Fusarium incarnatum LD-3. Keywords Solid substrate fermentation (SSF) . Laccase . Lignocellulosic substrate . Inducers . Litter-dwelling fungi . Fusarium incarnatum LD-3 Introduction Laccase (benzenediol:oxygen oxidoreductase (E.C.1.10.3.2), is a type of copper protein belonging to the oxidoreductase family (Thurston 1994; Brenna and Bianchi 1994). This en- zyme is a glycoprotein with molecular masses of 50–130 kDa and requires oxygen to oxidize phenols, polyphenols, aromatic amines, and other non-phenolic compounds. When oxidized by laccase, the reducing substrate uses a single electron and usually forms a free radical, which may undergo further lac- case catalyzed oxidation or non-enzymatic reactions including hydration, disproproteonation, and polymerization. Radicals, and other small molecules called as mediators, contribute significantly to the degradation of non-phenolic compounds present in the lignin. Laccases have a broad range of industrial and biotechnological applications. Currently, laccases are used in pulp delignification, textile dye bleaching, effluent detoxifi- cation, washing powder components, removal of phenolics from cork stoppers.(Brenna and Bianchi 1994), transformation of antibiotics and steroids (Breen and Singleton 1999), and in nanobiotechnology for the development of biosensors to detect various phenoloic compounds, oxygen, or azides (Ghindilis et al. 1992). In nature, laccase is found in the diverse group of organisms such as plants, bacteria, insects, and fungi. Howev- er, most of the studies have so far been focused on the model white rot species Trametes versicolor , Pleurotus ostreatus, and a few others. There are few studies on the litter-dwelling fungi, especially ascomycetes involved in the production and distri- bution of phenoloxidases, laccases, and peroxidases (Steffen et al. 2000, 2003). There are several reports in the literature on the production of laccase in ascomycetes such as Gaeuman- nomyces graminis (Edens et al. 1999), Magnaporthe grisea (Iyer and Chattoo 2003), Ophiostoma novo-ulmi (Binz and Canevascini 1997), and Neurospora crassa (Froehner and Eriksson 1974). In addition to such plant pathogenic species, U. Chhaya : A. Gupte (*) Department of Microbiology, Natubhai V. Patel College of Pure and Applied Sciences affiliated to Sardar Patel Universigy, Vallabh-Vidyanagar 388120, Gujarat, India e-mail: akshaya_gupte@hotmail.com Ann Microbiol (2013) 63:215–223 DOI 10.1007/s13213-012-0464-1