9-08: Fungal pullulan production from acid-hydrolyzed prairie cordgrass

Tuesday, May 1, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Thomas P. West and Jessica L. Peterson, Biology and Microbiology, South Dakota State University, Brookings, SD
Pullulan is a commercially available polysaccharide gum that has a variety of industrial applications. Prior work has not studied whether pullulan could be synthesized by the fungus Aureobasidium pullulans from glucose released from hydrolyzed plant biomass. Potential sources of plant biomass are prairie grasses such as prairie cordgrass since they produce a high yield with minimal fertilizer input. At present, prairie grasses are primarily utilized for livestock grazing or harvested as hay for livestock foraging. With prairie cordgrass containing about 30% cellulose, the cellulose could be hydrolyzed to glucose which is known to support fungal pullulan production as a carbon source. In this study, the ability of A. pullulans ATCC 42023 to utilize a prairie cordgrass hydrolysate produced by acid treatment to synthesize pullulan was investigated. The acid hydrolysate was prepared by adding 1% sulfuric acid to dried, ground grass and the mixture (10% solids) being autoclaved at 121oC for 30 minutes. The 1% sulfuric acid-treated cordgrass was filtered and the filtrate was used in a phosphate-buffered medium (pH 6.0) to grow the fungus. The fungal cells were grown for 168 hours at 30oC in shake flask cultures. After samples of the culture medium were collected and subjected to centrifugation, the pullulan concentration in the resultant supernatants was determined gravimetrically. The highest pullulan level was produced by A. pullulans ATCC 42023 after 168 hours of growth on the acid hydrolysate-containing medium. In conclusion, it was found that A. pullulans was capable of producing the polysaccharide from acid-hydrolyzed prairie cordgrass. 
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