PROIMI   05436
PLANTA PILOTO DE PROCESOS INDUSTRIALES MICROBIOLOGICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Thermal and Alkaline Denaturation of the Polysaccharide Scleroglucan Produced by Sclerotium rolfsii in Submerged Culture
Autor/es:
VIÑARTA SC; FIGUEROA LIC; SIÑERIZ F; FARIÑA JI
Lugar:
Denver Colorado
Reunión:
Congreso; Annual Meeting and Exhibition 2007 of the Society for Industrial Microbiology (SIM); 2007
Institución organizadora:
Society for Industrial Microbiology,
Resumen:
Abstract Scleroglucan is a neutral water-soluble b-1,3-b-1,6-glucan produced by Sclerotium rolfsii ATCC 201126. 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 recorded. For electron microscopy, scleroglucan gels were subjected to different temperatures (65º, 95º and 150ºC) 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 at 150ºC 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.