Monday, July 30, 2007
P28
Thermal and Alkaline Denaturation of the Polysaccharide Scleroglucan Produced by Sclerotium rolfsii in Submerged Culture
Silvana C. Viñarta1, Lucia I.C. de Figueroa1, Faustino Siñeriz2, and Julia I. Fariña1. (1) Fungal Biotechnology, PROIMI-CONICET, Av. Belgrano y Pje.Caseros, San Miguel de Tucumán, Argentina, (2) Environmental Microbiology, PROIMI-CONICET, Av. Belgrano y Pje.Caseros, San Miguel de Tucumán, 4000, Argentina
Scleroglucan is a neutral water-soluble beta-1,3-beta-1,6-glucan produced by Sclerotium rolfsii ATCC 201126. Its unique properties make it especially attractive for diverse industrial applications. In neutral aqueous solutions scleroglucan adopts a triple helical conformation. Denaturation into single coiled chains may occur at high pH, high temperature and/or in DMSO. Effects of pH and temperature onto the solution properties of scleroglucan were herein evaluated.
Scleroglucan produced by S. rolfsii ATCC 201126 at fermenter scale after 72 h of cultivation was recovered and subsequently purified. Events occurred during the dissolution of scleroglucan granules were monitored using polarized light microscopy. Topological changes were also studied by scanning electron microscopy (SEM). Light microscopy was performed using Nomarsky differential interference contrast (DIC) optics with scleroglucan granules placed between glass slide and cover slip. A small amount of water plus NaOH was added at the edges and dissolution process was thereafter recorded. For electron microscopy, scleroglucan gels were subjected to different temperatures (65, 95 and150ºC ) and NaOH concentrations (0.1, 0.15, 0.3 and 1.0 M).
Light microscopy showed that the total dissolution process of scleroglucan granules took about 8-14 seconds, but it probably depends on NaOH molarity. Granule swelling was followed by a loss of structure until it became almost invisible. SEM showed scleroglucan topologies in accordance with denaturation at150ºC and at NaOH concentrations higher than 0.15 M.
These results are particularly valuable not only for the polysaccharide characterization, but also for the design of downstream processing after fermentation and further applications at industrial level.
Scleroglucan produced by S. rolfsii ATCC 201126 at fermenter scale after 72 h of cultivation was recovered and subsequently purified. Events occurred during the dissolution of scleroglucan granules were monitored using polarized light microscopy. Topological changes were also studied by scanning electron microscopy (SEM). Light microscopy was performed using Nomarsky differential interference contrast (DIC) optics with scleroglucan granules placed between glass slide and cover slip. A small amount of water plus NaOH was added at the edges and dissolution process was thereafter recorded. For electron microscopy, scleroglucan gels were subjected to different temperatures (65, 95 and
Light microscopy showed that the total dissolution process of scleroglucan granules took about 8-14 seconds, but it probably depends on NaOH molarity. Granule swelling was followed by a loss of structure until it became almost invisible. SEM showed scleroglucan topologies in accordance with denaturation at
These results are particularly valuable not only for the polysaccharide characterization, but also for the design of downstream processing after fermentation and further applications at industrial level.
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See more of The Annual Meeting and Exhibition 2007 (July 29 - August 2, 2007)