agaroheteropolysaccharide present in red algae, was previously known to have
antioxidant properties, but the agarose hydrolase A33 amplified those properties by
breaking it down. Moreover, because antioxidant activity is not amplified when
porphyran is broken down with b-agarose hydrolase, this property is unique to
a-agarose hydrolase.
As this shows, agarose hydrolases with various properties are being obtained
from bacteria isolated from deep-sea waters or soil. These include many with
diverse and exceptional properties, including high heat tolerance and the formation
of specific reaction products, which may prove useful for industrial purposes in the
future (Fu and Kim 2010).
11.4.3 Heat-Resistant Cellulase
Pyrococcus horikoshii, a hyperthermophilic obligate anaerobe from the Archaea
domain that grows under anaerobic conditions at temperatures of 100 °C and greater,
has been isolated from hydrothermal deposits off the coast of Japan. Analysis of this
microorganism’s genome by the National Institute of Technology and Evaluation
resulted in cloning of a gene for EGPh, an endo-type cellulase with a molecular
weight of 42,000 that belongs to GHF5. EGPh is produced in E. coli, but a differential
scanning calorimeter (DSC) analysis showed a denaturing temperature of 96 °C. Its
optimal temperature for activity was found to be near 100 °C, and it did not lose
activity when heated up to 95 °C, indicating that it is a heat-resistant cellulose
(Zhang et al. 2014; Kawarabayasi et al. 1998; Ando et al. 2002).
Additionally, EGPh has proven degradable not only with the soluble cellulase
substrate carboxymethylcellulose (CMC), but also with avicel, an insoluble substrate that is difficult to degrade because of its high crystallinity. Protein engineering
research was subsequently performed on EGPh’s structure and functions, and
important amino acid residues and local structures are being surmised for the
enzyme’s functions.
Cellulose saccharification with cellulase is applicable in various processes for the
improvement of products through the breakdown of cellulose chains, including pulp
bleaching and fiber cleaning. As a heat-resistant cellulase, EgPh is used as an
enzyme for cotton fiber processing, which takes place at around 70 °C, and has
proven effective at improving fiber flexibility and color in jeans. It may also be
useful in the future saccharification of cellulose biomass and the production of
cellooligosaccharides. The enzyme can be mass-produced through an expression
system with Brevibacillus brevis as host.
11.4.4 Cold-Adapted Enzymes
For the most part, deep-sea waters are a low-temperature environment in the range
of 2–4 °C. Even at these low temperatures, microorganisms are known to live at
similar densities to those found in warm waters (10
5
–10
6 cell/mL) (Zeng 2006).
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11 Marine Microorganism Resources and Biotechnology
antioxidant properties, but the agarose hydrolase A33 amplified those properties by
breaking it down. Moreover, because antioxidant activity is not amplified when
porphyran is broken down with b-agarose hydrolase, this property is unique to
a-agarose hydrolase.
As this shows, agarose hydrolases with various properties are being obtained
from bacteria isolated from deep-sea waters or soil. These include many with
diverse and exceptional properties, including high heat tolerance and the formation
of specific reaction products, which may prove useful for industrial purposes in the
future (Fu and Kim 2010).
11.4.3 Heat-Resistant Cellulase
Pyrococcus horikoshii, a hyperthermophilic obligate anaerobe from the Archaea
domain that grows under anaerobic conditions at temperatures of 100 °C and greater,
has been isolated from hydrothermal deposits off the coast of Japan. Analysis of this
microorganism’s genome by the National Institute of Technology and Evaluation
resulted in cloning of a gene for EGPh, an endo-type cellulase with a molecular
weight of 42,000 that belongs to GHF5. EGPh is produced in E. coli, but a differential
scanning calorimeter (DSC) analysis showed a denaturing temperature of 96 °C. Its
optimal temperature for activity was found to be near 100 °C, and it did not lose
activity when heated up to 95 °C, indicating that it is a heat-resistant cellulose
(Zhang et al. 2014; Kawarabayasi et al. 1998; Ando et al. 2002).
Additionally, EGPh has proven degradable not only with the soluble cellulase
substrate carboxymethylcellulose (CMC), but also with avicel, an insoluble substrate that is difficult to degrade because of its high crystallinity. Protein engineering
research was subsequently performed on EGPh’s structure and functions, and
important amino acid residues and local structures are being surmised for the
enzyme’s functions.
Cellulose saccharification with cellulase is applicable in various processes for the
improvement of products through the breakdown of cellulose chains, including pulp
bleaching and fiber cleaning. As a heat-resistant cellulase, EgPh is used as an
enzyme for cotton fiber processing, which takes place at around 70 °C, and has
proven effective at improving fiber flexibility and color in jeans. It may also be
useful in the future saccharification of cellulose biomass and the production of
cellooligosaccharides. The enzyme can be mass-produced through an expression
system with Brevibacillus brevis as host.
11.4.4 Cold-Adapted Enzymes
For the most part, deep-sea waters are a low-temperature environment in the range
of 2–4 °C. Even at these low temperatures, microorganisms are known to live at
similar densities to those found in warm waters (10
5
–10
6 cell/mL) (Zeng 2006).
400
11 Marine Microorganism Resources and Biotechnology