Saccharification of cellulose by the cellulolytic enzyme system of Thermomonospora sp. II. Hydrolysis of cellulosic substrates

Abstract

AbstractA saccharification of cellulosic material using culture filtrate from the stationary phase of a culture of Thermomonospora sp. produced primarily cellobiose up to levels inhibitory to further saccharification, while the use of whole broth resulted in the production of glucose as well. Glucose production was enhanced and continued throughout the saccharification (24–36 hr) by several additions of cellobiase activity in the form of culture solids. Using Solka‐Floc as substrate, the “difference sugar” level (total soluble sugar minus glucose) rapidly rose to the same relatively stable concentration under various hydrolysis conditions, which was independent of the total sugar and glucose concentrations. A rapid hydrolusis rate was observed initially during saccharification, followed by a much slower rate of sugar production. Repeated centrifugation of the reaction mixture and replacement of the supernatant with fresh enzyme solution resulted each time in the reinitiation of a rapid hydrolysis rate. Saccharifications using A vicel microcrystalline cellulose, acid‐swollen cellulose, and cotton as substrates were also studied. A modified method of making phosphoric‐acid swollen cellulose is described. Saccharification of this substrate by culture filtrate and sequential additions of culture solids resulted in an inverse relationship between the attained glucose concentration and cellobiose‐cellotriose concentrations.