Biotechnological Potential of Marine Microbes 26.3 From Viruses to Microbial Eukaryotes 655
Part E | 26.3
investigated. One was the isolation of enzymes from
some hyperthermophilic archaea. The vent polymerase
was isolated from the marine archaeon Thermococcus
litoralis, and is currently marketed as a useful alternative to the widely used Taq deoxyribonucleic acid
(Taq DNA: a thermostable DNA polymerase named
after the thermophilic bacterium Thermus aquaticus;
Pfu DNA: a thermostable DNA polymerase named after the thermophilic bacterium Pyrococcus furiosus)
polymerase. The Pfu DNA polymerase, isolated by
the hyperthermophilic archaeon Pyrococcus furiosus,
is commercially available and possesses a higher fidelity compared with other conventional Taq DNA
polymerases [26.48]. Research into high-fidelity enzymes from marine archaea is still ongoing and is
continuously yielding new findings [26.49].
Marine archaea have been also exploited in several
industrial sectors. A heat and acid stable ˛-amylase,
Valley Ultra-Thin, discovered from a deep-sea hydrothermal vent archaeon, has been developed to facilitate the processing of corn into ethanol [26.17]. Marine
archaea can be important producers of biopolymers and
bioplastics, such as PHA (polyhydroxyalkanoate), and
a source of new secondary metabolites [26.17]. Recent studies have pointed out the importance of aquatic
archaea as useful agents for hydrocarbon biodegradation and decontamination of polluted areas [26.50],
indicating a potential, underexploited opportunity for
biotechnological investigations.
26.3.3 Marine Bacteria
Bacteria are typically the most abundant and diverse
members of the microbial biota in pelagic and benthic
ecosystems. They typically outnumber archaea, despite
exceptions in certain habitats [26.51, 52] and are the key
players in biogeochemical processes and the fluxes of
energy and matter in the ocean. Many bacterial species
are distributed across marine ecosystems worldwide.
Candidatus Pelagibacter ubique, a marine bacterium,
is recognized as being one of the most abundant organisms on Earth [26.31].
Marine bacteria have been largely exploited for
several biotechnological applications. Most of the marine bioactive compounds that have been successfully
screened originate from bacteria [26.4]. Marine bacteria, especially actinomycetes, are important producers
of antimicrobial secondary metabolites and antibiotics
(see [26.32] for a review). Marine actinomycetes produce different types of secondary metabolites, a large
fraction of which possess biological activities and
have the potential to be developed as therapeutic
agents [26.53]. Many other marine bacteria display
significant antibacterial activity [26.54], and they are
believed as an exciting resource for discovering new
classes of therapeutics within the areas of oncology and
infectious diseases [26.55]. Marine cyanobacteria also
produce bioactive and cytotoxic molecules that are useful as drugs [26.56, 57].
Unique biosynthetic enzymes from marine bacteria have begun to emerge as powerful biocatalysts in
medicinal chemistry and total synthesis [26.58]. Marine bacteria are important producers of biopolymers
and biodegradable plastics [26.59], pigments (including melanin, which is potentially exploitable for sunscreens, dyes, and coloring), cohesive molecules that
are useful as marine cements, and extracellular substances that are useful as surfactants ([26.22] and references therein).
The surface of many marine macroorganisms such
as, to mention only a few, sponges [26.60], algae [26.61], tropical stony corals [26.62, 63], coldwater corals [26.64], hydroids [26.65], crabs [26.66,
67], and fishes, is a particularly interesting niche to
study marine bacteria and other microorganisms with
respect to biotechnology. The surface of virtually all
marine macroorganisms hosts abundant and diverse
communities of microbes [26.68]. For instance, the tissue of stony corals typically harbors an associated and
diversified microbial community (Fig. 26.2), consisting of archaea, bacteria, and eukaryotes [26.69, 70].
Similarly, marine sponges typically contain diverse and
abundant microbial communities, made up of bacteria, archaea, microalgae, and fungi, which comprise
up to 40% of the sponge volume and contribute significantly to the host metabolism [26.60]. Microbial
associates are believed to have several functions for the
sponge, such as stabilization of the sponge skeleton,
nutrient uptake, processing of metabolic waste, and secondary metabolite production. An increasing number
of studies is documenting the existence of close associations between prokaryotes and higher eukaryotic
organisms, typically forming mutualistic or symbiotic
relationships [26.17]. Chemically-driven interactions
are thought to be important in the establishment of relationships between epibiotic microorganisms and their
eukaryotic hosts. For instance, soft-bodied marine organisms lack obvious structural defense mechanisms
and rely on chemical defense, by production of bioactive compounds (either by themselves or the associated
microflora), to survive [26.71]. Marine invertebrates are
a rich source of bioactive metabolites, yet recent stud-
Part E | 26.3
investigated. One was the isolation of enzymes from
some hyperthermophilic archaea. The vent polymerase
was isolated from the marine archaeon Thermococcus
litoralis, and is currently marketed as a useful alternative to the widely used Taq deoxyribonucleic acid
(Taq DNA: a thermostable DNA polymerase named
after the thermophilic bacterium Thermus aquaticus;
Pfu DNA: a thermostable DNA polymerase named after the thermophilic bacterium Pyrococcus furiosus)
polymerase. The Pfu DNA polymerase, isolated by
the hyperthermophilic archaeon Pyrococcus furiosus,
is commercially available and possesses a higher fidelity compared with other conventional Taq DNA
polymerases [26.48]. Research into high-fidelity enzymes from marine archaea is still ongoing and is
continuously yielding new findings [26.49].
Marine archaea have been also exploited in several
industrial sectors. A heat and acid stable ˛-amylase,
Valley Ultra-Thin, discovered from a deep-sea hydrothermal vent archaeon, has been developed to facilitate the processing of corn into ethanol [26.17]. Marine
archaea can be important producers of biopolymers and
bioplastics, such as PHA (polyhydroxyalkanoate), and
a source of new secondary metabolites [26.17]. Recent studies have pointed out the importance of aquatic
archaea as useful agents for hydrocarbon biodegradation and decontamination of polluted areas [26.50],
indicating a potential, underexploited opportunity for
biotechnological investigations.
26.3.3 Marine Bacteria
Bacteria are typically the most abundant and diverse
members of the microbial biota in pelagic and benthic
ecosystems. They typically outnumber archaea, despite
exceptions in certain habitats [26.51, 52] and are the key
players in biogeochemical processes and the fluxes of
energy and matter in the ocean. Many bacterial species
are distributed across marine ecosystems worldwide.
Candidatus Pelagibacter ubique, a marine bacterium,
is recognized as being one of the most abundant organisms on Earth [26.31].
Marine bacteria have been largely exploited for
several biotechnological applications. Most of the marine bioactive compounds that have been successfully
screened originate from bacteria [26.4]. Marine bacteria, especially actinomycetes, are important producers
of antimicrobial secondary metabolites and antibiotics
(see [26.32] for a review). Marine actinomycetes produce different types of secondary metabolites, a large
fraction of which possess biological activities and
have the potential to be developed as therapeutic
agents [26.53]. Many other marine bacteria display
significant antibacterial activity [26.54], and they are
believed as an exciting resource for discovering new
classes of therapeutics within the areas of oncology and
infectious diseases [26.55]. Marine cyanobacteria also
produce bioactive and cytotoxic molecules that are useful as drugs [26.56, 57].
Unique biosynthetic enzymes from marine bacteria have begun to emerge as powerful biocatalysts in
medicinal chemistry and total synthesis [26.58]. Marine bacteria are important producers of biopolymers
and biodegradable plastics [26.59], pigments (including melanin, which is potentially exploitable for sunscreens, dyes, and coloring), cohesive molecules that
are useful as marine cements, and extracellular substances that are useful as surfactants ([26.22] and references therein).
The surface of many marine macroorganisms such
as, to mention only a few, sponges [26.60], algae [26.61], tropical stony corals [26.62, 63], coldwater corals [26.64], hydroids [26.65], crabs [26.66,
67], and fishes, is a particularly interesting niche to
study marine bacteria and other microorganisms with
respect to biotechnology. The surface of virtually all
marine macroorganisms hosts abundant and diverse
communities of microbes [26.68]. For instance, the tissue of stony corals typically harbors an associated and
diversified microbial community (Fig. 26.2), consisting of archaea, bacteria, and eukaryotes [26.69, 70].
Similarly, marine sponges typically contain diverse and
abundant microbial communities, made up of bacteria, archaea, microalgae, and fungi, which comprise
up to 40% of the sponge volume and contribute significantly to the host metabolism [26.60]. Microbial
associates are believed to have several functions for the
sponge, such as stabilization of the sponge skeleton,
nutrient uptake, processing of metabolic waste, and secondary metabolite production. An increasing number
of studies is documenting the existence of close associations between prokaryotes and higher eukaryotic
organisms, typically forming mutualistic or symbiotic
relationships [26.17]. Chemically-driven interactions
are thought to be important in the establishment of relationships between epibiotic microorganisms and their
eukaryotic hosts. For instance, soft-bodied marine organisms lack obvious structural defense mechanisms
and rely on chemical defense, by production of bioactive compounds (either by themselves or the associated
microflora), to survive [26.71]. Marine invertebrates are
a rich source of bioactive metabolites, yet recent stud-