11.4.5 Alginate Lyase Functioning Under Alkaline Conditions
Alkaline enzymes are enzymes with an optimum pH in the alkaline range above 9.
Most of them are produced outside the body by alkaliphilic microorganisms. Many
proteases and cellulases are known to be alkaline enzymes. Bacteria from the genus
Agarivorans isolated from deep-sea mud have been found to produce the alginate
lyase A1m, which functions under alkaline conditions. Based on protein electrophoresis (sodium dodecyl sulfate polyacrylamide gel, or SDS-PAGES), A1m is
predicted to have a mass of 31 kDa. Its optimum pH is 10, and its activity was
found to increase by 1.8 times with the addition of 0.2 M NaCl (Hattori et al. 1997).
Alginate lyases are found in bacteria, fungi, brown algae, mollusks, and viruses.
Most are semi-alkaline enzymes with an optimal pH in the weak base range. A1m is
thus regarded as an alginate lyase with optimum conditions at the highest end of the
pH range. Because solubility of the alginate substrate increases sharply in the highly
alkaline range, an alkaline alginate lyase exhibiting strong activity under these
conditions can be viewed as well suited to alginate breakdown.
Other alginate lyases found in mollusks are useful for the manufacturing of
various bioactive alginic acid oligosaccharides or the use of alginic acid in saccharification and biomass. It is expected that these will be put to many effective uses
in the future with seaweed biomass.
A number of marine microorganisms contain alginate lyases, most notably
bacteria from the Alteromonas, Pseudoalteromonas, and Vibrio genera. These are
believed to play the role of final decomposer of the alginic acid containing in brown
algae detritus.
11.4.6 Metagenomically Derived Esterase
Ninety-nine percent of microorganisms on the planet are regarded as “viable but
nonculturable” (VBNC) bacteria due to the difficulty of isolating and culturing
them. The term metagenome refers to VBNC bacterial DNA in its mixed state when
directly extracted from its environment. This can be developed into a library
(metagenomic library) allowing for metagenomics analysis through the reading of
its base sequence. Next-generation DNA base sequence measurement equipment
can be used to produce large volumes of base sequence information in a short time,
while advancements in bioinformatics technology and high-throughput activity
detection technology have facilitated the hunt for new enzyme genes.
Metagenomic analysis has been performed on a number of marine organisms to
date, including VBNC bacteria present in seawater and sea mud and sponges and
corals containing large amounts of symbiotic microorganisms. This has led to
the discovery of numerous enzyme genes. This section will focus on the esterases
(EC 3.1.1.1) obtained from the metagenomic libraries of sponges and sea mud
(Chu et al. 2008; Steele et al. 2009).
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11 Marine Microorganism Resources and Biotechnology
Alkaline enzymes are enzymes with an optimum pH in the alkaline range above 9.
Most of them are produced outside the body by alkaliphilic microorganisms. Many
proteases and cellulases are known to be alkaline enzymes. Bacteria from the genus
Agarivorans isolated from deep-sea mud have been found to produce the alginate
lyase A1m, which functions under alkaline conditions. Based on protein electrophoresis (sodium dodecyl sulfate polyacrylamide gel, or SDS-PAGES), A1m is
predicted to have a mass of 31 kDa. Its optimum pH is 10, and its activity was
found to increase by 1.8 times with the addition of 0.2 M NaCl (Hattori et al. 1997).
Alginate lyases are found in bacteria, fungi, brown algae, mollusks, and viruses.
Most are semi-alkaline enzymes with an optimal pH in the weak base range. A1m is
thus regarded as an alginate lyase with optimum conditions at the highest end of the
pH range. Because solubility of the alginate substrate increases sharply in the highly
alkaline range, an alkaline alginate lyase exhibiting strong activity under these
conditions can be viewed as well suited to alginate breakdown.
Other alginate lyases found in mollusks are useful for the manufacturing of
various bioactive alginic acid oligosaccharides or the use of alginic acid in saccharification and biomass. It is expected that these will be put to many effective uses
in the future with seaweed biomass.
A number of marine microorganisms contain alginate lyases, most notably
bacteria from the Alteromonas, Pseudoalteromonas, and Vibrio genera. These are
believed to play the role of final decomposer of the alginic acid containing in brown
algae detritus.
11.4.6 Metagenomically Derived Esterase
Ninety-nine percent of microorganisms on the planet are regarded as “viable but
nonculturable” (VBNC) bacteria due to the difficulty of isolating and culturing
them. The term metagenome refers to VBNC bacterial DNA in its mixed state when
directly extracted from its environment. This can be developed into a library
(metagenomic library) allowing for metagenomics analysis through the reading of
its base sequence. Next-generation DNA base sequence measurement equipment
can be used to produce large volumes of base sequence information in a short time,
while advancements in bioinformatics technology and high-throughput activity
detection technology have facilitated the hunt for new enzyme genes.
Metagenomic analysis has been performed on a number of marine organisms to
date, including VBNC bacteria present in seawater and sea mud and sponges and
corals containing large amounts of symbiotic microorganisms. This has led to
the discovery of numerous enzyme genes. This section will focus on the esterases
(EC 3.1.1.1) obtained from the metagenomic libraries of sponges and sea mud
(Chu et al. 2008; Steele et al. 2009).
402
11 Marine Microorganism Resources and Biotechnology