Utilization of corn fiber for production of schizophyllan
2016
Leathers, Timothy D. | Nunnally, Melinda S. | Stanley, April M. | Rich, Joseph O.
Corn fiber is an abundant lignocellulosic biomass resource produced during the wet milling of corn. Although corn fiber is recalcitrant to enzymatic digestion, the fungus Schizophyllum commune was able to directly utilize corn fiber for production of the valuable bioproduct schizophyllan. Schizophyllan is a biopolymer composed entirely of glucose, with a β-1,3-linked backbone and single β-1,6-linked glucose side chains at every third residue. Schizophyllan is being developed for bulk biomaterial applications, such as in enhanced oil recovery and as a component of biolubricants. S. commune strain ATCC 38548 produced up to 6.8 ± 0.2 g dm−3 schizophyllan when grown in malt extract medium containing 10 g dm−3 untreated corn fiber in place of glucose. Pretreatment of corn fiber with alkaline hydrogen peroxide enhanced yields of schizophyllan. Corn steep liquor at 50 cm3 dm−3 could replace malt extract as a nitrogen source, producing up to 5.4 ± 1.6 g dm−3 schizophyllan and 6.0 ± 0.5 g dm−3 schizophyllan from 10 g dm−3 untreated and pretreated corn fiber, respectively. Glucose (from corn syrup) further enhanced yields, substituting for the maltose component of malt extract. Schizophyllan produced from corn fiber exhibited a high molecular weight of 3.2 × 107 Da, with solution viscosity properties characteristic of schizophyllan. Utilization of corn fiber could reduce the cost of schizophyllan production and provide a value-added coproduct from corn processing biomass.
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