Project Number: 3620-41000-135-06
Start Date: Oct 01, 2013
End Date: Sep 30, 2014
In previous studies, we demonstrated the feasibility of schizophyllan production by fermentation of corn fiber and distiller’s dried grains with solubles (DDGS) (Leathers et al. 2006; Sutivisedsak et al. 2013). For the current project, we will focus on cost-effective production of schizophyllan from corn fiber. S. commune is a mushroom and white-rot fungus that produces the hydrolytic enzymes (cellulase and xylanase) necessary to break down corn fiber. Thus, it is not necessary to add expensive commercial enzymes to saccharify corn fiber for fermentation to schizophyllan. However, our previous studies used a relatively expensive basal medium containing commercial malt extract and peptone. For the current project, we will formulate less expensive alternative media, for example containing corn steep liquor. Corn fiber will be untreated or minimally pretreated. Fermentation conditions (pH, temperature, aeration, and agitation) will be optimized for the best of these media. Using optimized conditions, fermentations of corn fiber to schizophyllan will be scaled up. In preliminary studies, we have produced 0.45 g schizophyllan/g DDGS in 1.5 L controlled bioreactors (unpublished). For the current project, our goal will be to use optimized corn fiber fermentations to scale up to 20 L fermentors, available in our laboratories at NCAUR. This will provide sufficient material for analysis and potential applications testing. Schizophyllan is conventionally recovered from fermentation supernatants using an expensive process necessary for production of cosmetic and pharmaceutical-grade material. In preliminary studies, we have tested a simplified downstream process that reduces dilution of the culture supernatants and eliminates expensive reconcentration/purification steps (unpublished). Bulk schizophyllan produced by this method has shown composition and viscosity profiles equivalent to those of commercial schizophyllan (unpublished). For the current project, downstream processing will be further refined for economical recovery of corn fiber-based schizophyllan. Finally, the chemical and physical properties of corn fiber-based schizophyllan will be characterized to evaluate its potential for large-scale industrial applications. Total sugar and linkage composition will be determined using GC/MS and methylation analyses as previously described (Sutivisedsak et al., 2013). The viscosity of corn fiber-based schizophyllan will be determined as a function of concentration and shear thinning. The viscosity profile of schizophyllan is its single most important functional characteristic for potential bulk applications in enhanced oil recovery and biolubricants.