Article

Applied Biochemistry and Biotechnology

, Volume 118, Issue 1, pp 177-188

First online:

Differential thermal and thermogravimetric analyses of bound water content in cellulosic substrates and its significance during cellulose hydrolysis by alkaline active fungal cellulases

  • Santosh VyasAffiliated withDivision of Biochemical Sciences, National Chemical Laboratory
  • , S. D. PradhanAffiliated withPhysical Chemistry Division, National Chemical Laboratory
  • , N. R. PavaskarAffiliated withPhysical Chemistry Division, National Chemical Laboratory
  • , Anil LachkeAffiliated withDivision of Biochemical Sciences, National Chemical Laboratory Email author 

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Abstract

Various cellulosic substrates were examined for bound water content by differential thermal analysis (DTA) and thermogravimetry (TG). Samples were heated in the range of 30–100°C at a rate of 3°/min. DTA vaporization curves for different cellulose samples indicated that the bound water (W b ) was vaporized at higher temperature than free water (W f ) at the surface. Weight loss was observed in two stages, corresponding to W f and W b in TG curves. The bound water content was dependent on the degree of crystallinity of cellulose. Among different cellulosic substrates, Walseth cellulose showed the highest bound water content, and it also was found to be the least crystalline. The alkaline-active, alkali-stable cellulase was obtained from the alkalotolerant Fusarium sp. The substrate specificity and viscometric characteristics confirmed the enzyme to be an endoglucanase. The W b content of Walseth cellulose was lowered during the enzymatic hydrolysis. The possible application of bound water analysis in understanding the hydrolysis of cellulosic substrates of different crystallinity is discussed.

Index Entries

Cellulose endoglucanase differential thermal analysis thermogravimetry bound water vaporization