called ‘‘taka-diastase’’ by Sankyo Co and was the pioneer of crude amylolytic
extracts produced by SSF. Such developments were reviewed by Takamine (1914).
Underkofler (1938) patented the use of rotating drums in order to produce
amylase by ‘‘moldy brans’’ or wheat bran fermented by A. oryzae. Underkofler
et al. (1939) suggested the advantage of moldy bran over malting or acid hydrolysis in order to improve the conversion of starch into ethanol. As indicated in the
preceding section, Underkofler et al. (1947) reported the successful industrial
scale-up of the moldy bran process but using trays instead of rotating drums
because of the attrition problems of fungal biomass by mechanical stirring. The
process was used to produce a crude amylolytic preparation blended with cooked
cereal grains that was the input for ethanol production. The final ethanol yields
were around 80 % of the theoretical yield. Hence, Takamine and Underkofler
planted the seeds of present bio-ethanol industries.
11.4 General Criteria for Developing Enzyme
Production by SSF
Basic research on the production of enzymes by SSF processes started around 1980,
and was published in more than 1,000 research papers but only a handful of enterprises have used this technology outside of China and Japan (Pandey et al. 1999;
Viniegra-González et al. 2003). Here, we discuss the need to develop and apply three
separate sets of criteria for the production of enzymes by SSF technology
(a) Improvement of microbial strains;
(b) Process control with special attention to changes in temperature and respiratory rates;
(c) Minimization of product recovery cost.
11.5 Improvement of Microbial Strains
11.5.1 Comparison of Enzyme Titers Between SSF
and SmF Processes
It is worth stressing that comparisons between SSF and SmF processes should be
done between industrial processes of similar throughput capacity. In order to
illustrate this matter, a practical calculation is presented.
Enzyme titers are reported using the International Unit (amount of enzyme with
activity = 1 9 10
-6 mole P min
-1 ) produced on the basis of initial dry weight of
a solid substrate (E S = IU kg
-1 ) for SSF processes or on the basis of fermentation
volume (E L = IU L
-1 ) for SmF processes.
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G. Viniegra-González
extracts produced by SSF. Such developments were reviewed by Takamine (1914).
Underkofler (1938) patented the use of rotating drums in order to produce
amylase by ‘‘moldy brans’’ or wheat bran fermented by A. oryzae. Underkofler
et al. (1939) suggested the advantage of moldy bran over malting or acid hydrolysis in order to improve the conversion of starch into ethanol. As indicated in the
preceding section, Underkofler et al. (1947) reported the successful industrial
scale-up of the moldy bran process but using trays instead of rotating drums
because of the attrition problems of fungal biomass by mechanical stirring. The
process was used to produce a crude amylolytic preparation blended with cooked
cereal grains that was the input for ethanol production. The final ethanol yields
were around 80 % of the theoretical yield. Hence, Takamine and Underkofler
planted the seeds of present bio-ethanol industries.
11.4 General Criteria for Developing Enzyme
Production by SSF
Basic research on the production of enzymes by SSF processes started around 1980,
and was published in more than 1,000 research papers but only a handful of enterprises have used this technology outside of China and Japan (Pandey et al. 1999;
Viniegra-González et al. 2003). Here, we discuss the need to develop and apply three
separate sets of criteria for the production of enzymes by SSF technology
(a) Improvement of microbial strains;
(b) Process control with special attention to changes in temperature and respiratory rates;
(c) Minimization of product recovery cost.
11.5 Improvement of Microbial Strains
11.5.1 Comparison of Enzyme Titers Between SSF
and SmF Processes
It is worth stressing that comparisons between SSF and SmF processes should be
done between industrial processes of similar throughput capacity. In order to
illustrate this matter, a practical calculation is presented.
Enzyme titers are reported using the International Unit (amount of enzyme with
activity = 1 9 10
-6 mole P min
-1 ) produced on the basis of initial dry weight of
a solid substrate (E S = IU kg
-1 ) for SSF processes or on the basis of fermentation
volume (E L = IU L
-1 ) for SmF processes.
326
G. Viniegra-González