polysaccharides and the saccharification of seaweed biomass has led to active
research in related enzymes.
11.4.1 Enzymes from Deep-Sea Microorganisms
The oceans that cover around 70% of the earth’s surface have an average depth of
around 3800 m, such that most of the marine environment consists of deep-sea
environments. At a depth of 3800 m, the oceans are a low-temperature (2–4 °C)
and high-pressure (38 MPa) environment. Some localized environments, such as
the areas around hydrothermal vents, also contain methane and hydrogen sulfide at
temperatures of over 300 °C (Ojima 2011).
While these marine environments are thought of as strict habitat conditions for
organisms, they are inhabited by a truly great number of arthropods, echinoderms,
annelids, and microorganisms, indicating great potential for the discovery of
enzymes with special, environmental adaption-related characteristics in organisms
that inhabit deep-sea environments.
11.4.2 Heat-Resistance Agarase
One of the chief components of agar, agarose is a recalcitrant polysaccharide with a
polymerized structure consisting of b-D-galactose and 3,6-anhydro-a-L-galactose.
It is found in red algae such as Gelidiales, Gigartinales, and Ceramiales. Within
agarose molecules, these constituent polysaccharides form agarobiose units
(4-O-b-D-dalactopyranosyl-3,6-anhydro-L-galactopyranose) or neoagarobiose units
(3-O-a-3,6-anhydro-L-galactopyranosyl-D-galactopyranose), where agarose polymers have structures linking these together (Pickett et al. 1981).
Agarose hydrolase is an enzyme that hydrolyzes the b-1-4 or a-1,6 linkage in
agarose, producing agarooligosaccharides such as neoagarobiose or agarobiose.
Agarose hydrolase that severs the beta-1,4 linkage to form neoagarooligosaccharides is called b-agarose hydrolase (EC 3.2.1.81), while the type that severs the
a-1,3 linkage to form agarooligosaccharides is known as a-agarose hydrolase (EC
3.2.1.158).
Agarose hydrolase production is rare in land-based microorganisms, but relatively common in microorganisms that inhabit sea mud. The sea floor microorganisms that produce agarose hydrolase are believed to use agar from settling red
algae detritus by breaking it down into agarose.
The neoagarooligosaccharides and agarooligosaccharides produced through
enzymatic breakdown of agarose exhibit a range of bioactivity in human beings,
including antitumor, antioxidation, immunostimulation, hydration, and whitening
effects. For this reason, efforts are currently under way to find agarose hydrolases
that can be used to efficiently produce these bioactive oligosaccharides.
Agarose possesses a structure in which agarobiose units—consisting of
b-D-galactose (b-D-Gal) and (3,6) anhydro-a-L-galactose (a-L-Gal) connected by
398
11 Marine Microorganism Resources and Biotechnology
research in related enzymes.
11.4.1 Enzymes from Deep-Sea Microorganisms
The oceans that cover around 70% of the earth’s surface have an average depth of
around 3800 m, such that most of the marine environment consists of deep-sea
environments. At a depth of 3800 m, the oceans are a low-temperature (2–4 °C)
and high-pressure (38 MPa) environment. Some localized environments, such as
the areas around hydrothermal vents, also contain methane and hydrogen sulfide at
temperatures of over 300 °C (Ojima 2011).
While these marine environments are thought of as strict habitat conditions for
organisms, they are inhabited by a truly great number of arthropods, echinoderms,
annelids, and microorganisms, indicating great potential for the discovery of
enzymes with special, environmental adaption-related characteristics in organisms
that inhabit deep-sea environments.
11.4.2 Heat-Resistance Agarase
One of the chief components of agar, agarose is a recalcitrant polysaccharide with a
polymerized structure consisting of b-D-galactose and 3,6-anhydro-a-L-galactose.
It is found in red algae such as Gelidiales, Gigartinales, and Ceramiales. Within
agarose molecules, these constituent polysaccharides form agarobiose units
(4-O-b-D-dalactopyranosyl-3,6-anhydro-L-galactopyranose) or neoagarobiose units
(3-O-a-3,6-anhydro-L-galactopyranosyl-D-galactopyranose), where agarose polymers have structures linking these together (Pickett et al. 1981).
Agarose hydrolase is an enzyme that hydrolyzes the b-1-4 or a-1,6 linkage in
agarose, producing agarooligosaccharides such as neoagarobiose or agarobiose.
Agarose hydrolase that severs the beta-1,4 linkage to form neoagarooligosaccharides is called b-agarose hydrolase (EC 3.2.1.81), while the type that severs the
a-1,3 linkage to form agarooligosaccharides is known as a-agarose hydrolase (EC
3.2.1.158).
Agarose hydrolase production is rare in land-based microorganisms, but relatively common in microorganisms that inhabit sea mud. The sea floor microorganisms that produce agarose hydrolase are believed to use agar from settling red
algae detritus by breaking it down into agarose.
The neoagarooligosaccharides and agarooligosaccharides produced through
enzymatic breakdown of agarose exhibit a range of bioactivity in human beings,
including antitumor, antioxidation, immunostimulation, hydration, and whitening
effects. For this reason, efforts are currently under way to find agarose hydrolases
that can be used to efficiently produce these bioactive oligosaccharides.
Agarose possesses a structure in which agarobiose units—consisting of
b-D-galactose (b-D-Gal) and (3,6) anhydro-a-L-galactose (a-L-Gal) connected by
398
11 Marine Microorganism Resources and Biotechnology