ABSTRACT

Solid-state fermentation (SSF) may be characterized as a fermentation process carried out on a solid medium with a low moisture content (Aw), typically 0.40-0.90 that occurs usually in a nonseptic and natural state (Nigam and Singh 1994). The SSF produces a high product concentration but has a relatively low energy requirement (Mudgett et al. 1992; Yang and Yuan 1990). Solid-state fermentation has been exploited for the production of fermented food (Bhumiratana et al. 1980; Heseltine 1983), and animalfeeds (GumbinaSaid 1996; Nigam and Singh 1996a; Sandhu and Joshi 1997). The production of ethanol as fuel (Hinman et al. 1992; Ingram et al. 1999; Lapadatescu and Bonnarme 1999), and the production of various enzymes including cellulolytic and lignolytic have been studied in SSF (Gombert et al. 1999; Nigam and Singh 1996b). Recently, SSF process has been applied for the bioremediation of textile effluent and dye degradation (Nigam et al. 2000; Robinson et al. 2001). Many of the solids used for SSF are unrefined and of agricultural origin (Balakrishnan and Pandey 1996; Durand et al. 1997) which makes the complete characterization and exact reproducibility of results difficult (Mitchell and Lonsane 1992). The SSF can be carried out on a variety of agricultural residues such as wheat straw, rice hulls, and corncobs. Solidstate fermentation has received greater interest from researchers, as several studies have demonstrated superior product yields and simplified downstream processing, following SSF (Barrios-Gonzalez et al. 1988; Maldonado and de Saad 1998).