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Title: Process development studies for the production of β-glucosidase from Aspergillus phoenicis

Thesis/Dissertation ·
DOI:https://doi.org/10.2172/6631209· OSTI ID:6631209
 [1];  [1]
  1. Univ. of California, Berkeley, CA (United States)

This work is concerned with the production of β-glucosidase from Aspergillus phoenicis for use in the enzymatic hydrolysis of cellulose. Kinetic growth data indicate that two distinct periods of growth exist. The observed growth kinetics result from a biochemical differentiation of the filament which is independent of the substrate concentration. The optimum temperature for cell mass and β-glucosidase production was found to be 30°C. The optimum pH for β-glucosidase production is 5 and the highest specific cell growth rate was observed when the growth medium was controlled at pH 4.5. The most economical substrate was 0.75 g/l of Solka Floc, a spruce wood pulp, plus 0.25 g/l of Trichoderma viride cellulase, required because A. phoenicis does not produce all the enzymes required to solubilize cellulose. When freeze-dried A. phoenicis enzyme was added to the hydrolysis of acid treated corn stover by Tricoderma viride cellulase, the total sugar yield was increased by 4 g/l of hydrolysate over the yield of 20 g/l obtained without β-glucosidase addition. In addition, the cellobiose, which accounted for about 10% of the sugar concentration, was converted to glucose, a more widely useable product. Preliminary designs of several processes for the production of β-glucosidase were made. The most economical processes were continuous production schemes. Ball milling was the most cost effective method, but the use of an elevated temperature stage was economical enough to warrant further study. The cost of production of β-glucosidase was found to be too high to justify its addition to a process for enzymatically hydrolyzing cellulose at this time.

Research Organization:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
6631209
Report Number(s):
LBL-7867
Resource Relation:
Other Information: Thesis
Country of Publication:
United States
Language:
English