IntroductionThe renewable material lignocellulose is the major component of biomass and consists of lignin, hemicellulose, and cellulose (1). It is the most abundant natural material in the world (2). Large quantities of lignocellulosic wastes (LCWs) are released from various industries such as food, agricultural, forestry, paper pulp, and timber. These wastes cause serious environmental pollution, but can be reused constructively rather than burned due to their rich sugar contents (3,4). The chemical properties of these lignocellulosic wastes make them a crucial and cost-effective fermentation medium for biotechnological applications (3). However, while the hemicellulose and cellulose components of lignocellulosic materials are used by numerous microorganisms, the lignin, which is the most resistant material to microbial degradation, is converted efficiently by only a limited number of organisms, such as white rot fungi (1). Lignin serves as a barrier that protects cellulose and hemicellulose from enzymatic attack; however, white rot fungi can attack this barrier in order to obtain energy from cellulose (5). These fungi produce different extracellular ligninolytic enzymes such as laccase, manganese peroxidase, and lignin peroxidase (6,7). Laccase (benzenediol: oxygen oxidoreductase; EC 1.10.3.2) has received much attention because of its relatively low substrate specificity in comparison to most enzymes, and for its potential application in different biotechnological, industrial, and environmental fields. This enzyme can be used for biopulping, biobleaching, wastewater treatment, decolorization of various dyes, enzymatic removal of phenolic compounds in beverages, construction of biosensors, and bioremediation (8-14). Laccase can be produced at varying rates by using a wide range of organisms grown on different substrates and by using several methods of fermentation, such as solid state, semisolid state, and submerged (15-18). However, for effective laccase production, it is very important to use efficient laccase-producing organisms, suitable fermentation methods, and cheap and widespread sources. Accordingly, one of the most suitable approaches for the production of this enzyme is to use the most efficient agricultural wastes for increasing the production of the ligninolytic enzymes (19).Agricultural wastes such as corncob and sunflower receptacle were tested as fungal fermentation media for laccase production in this study. Every year, approximately 2-3.10 6 and 85.10 5 t of corn and sunflower are produced in Turkey, respectively (20). In addition, approximately 26.10 6
