strated to be mediated by secondary metabolites. Therefore, associations of fungi and
macroorganisms are of special interest with
respect to the discovery of bioactive natural
products (Rashmi et al. 2019). Accordingly,
many screening campaigns led to the discovery
and subsequent identification of new compounds with interesting bioactivities, including
antibiotic, antiviral, antitumoral, etc. Marine
fungi produce structurally unique bioactive
natural products that are not found in terrestrial counterparts. Kong et al. showed that large
portions of marine scaffolds are novel (Kong
et al. 2010). Auranomides A and B, quinazolin4-ones substituted with a pyrrolidin-2-iminium
moiety from the marine-derived fungus Penicillium aurantiogriseum, or aspergillols A and
B with a C–C fusion of an anthraquinone and
orcinol unit from a deep-sea Aspergillus versicolor represent new scaffolds from marine habitats (Song et al. 2012; Wu et al. 2016). Probably,
these compounds constitute only a small portion of the possible repertoire, as drug discovery efforts often involve a specific focus, either
on disease target, taxonomic groups or on habitats, but do not aim to describe the full genetic
biosynthetic potential.
Today, only a few compounds made their
way to the pharmaceutical market. Marine fungal compounds do face the same challenges in
drug discovery and drug development as any
other fungal compounds. However, in the
1950s, cephalosporin C, a b-lactam type natural antibiotic, was discovered from a Cephalosporium (later reclassified as Acremonium)
strain obtained at the Sardinian coast (Newton
and Abraham 1955; Abraham et al. 1953). Gliotoxin was identified as a new type of the antibiotic diketopiperazine produced by a marine
deep-sea sediment Aspergillus sp. strain (Okutani 1977).
Marine fungi did also prove to be effective
producers of natural products with antitumoral
activity (Pejin and Karaman 2017). However,
halamid, an anticancer compound of marine
fungal origin (trade name plinabulin) is the
only one already being in clinical testing
phase 2 and 3 for different indications (for
review see Pereira et al. 2019). Nevertheless,
the current chemotherapeutic clinical pipeline
will be fed with marine-derived fungal agents,
which are in preclinical stage at the moment.
A steadily increasing number of new, active
fungal natural products have been identified
from the marine environment, proving them
to be a prolific source for bioactive compounds:
Blunt et al. listed over 200 natural products
from marine-sourced fungi (excluding those
from mangroves) in the year 2013 (Blunt et al.
2015). Cosmetic and cosmeceutical applications might also be taken into account for
marine fungal secondary metabolites (Agrawal
et al. 2018). Here, biotechnological approaches
can help to close the developmental gap
between discovery and production in order to
solve compound availability issues in drug
development (as reviewed for antibiotics in Silber et al. 2016).
B. Enzymes
Marine fungi can be used for the biotechnological production of salt- and osmostable enzyme
variants but do also provide new enzymatic
activities. Fungi foster, e.g., the detrital processes by production of extracellular degradative enzymes (Sikes et al. 2009). These fungal
enzymes from marine origin can be used in
biotechnological applications. Extracellular degradative enzymes such as cellulases, xylanases,
and ligninases of several terrestrial fungi already
have found biotechnological applications in
paper and pulp industries, food production,
and clothing industry. Fungi isolated from living
and decaying marine plant material are capable
of degrading “classical” plant macromolecules,
like cellulose, cellobiose, lipids, pectin, starch,
xylan, and tannic acid (Gessner 1980). In addition, marine fungi can degrade the special carbohydrates found in marine plants, such as
alginates, sulfated polysaccharides, laminarin,
fucoidan, etc. (as early described as in Schaumann and Weide 1990). These enzymes can be
applied in transforming these sugars for energetic use of algal remaining’s (e.g., for biogas
production) especially from aquacultures. Also,
fungal polygalacturonases are useful enzymes
for clarification of fruit juices in the food industry (Sandri et al. 2011).
16 Biotechnology of Marine Fungi: New Workhorses and Applications
405
macroorganisms are of special interest with
respect to the discovery of bioactive natural
products (Rashmi et al. 2019). Accordingly,
many screening campaigns led to the discovery
and subsequent identification of new compounds with interesting bioactivities, including
antibiotic, antiviral, antitumoral, etc. Marine
fungi produce structurally unique bioactive
natural products that are not found in terrestrial counterparts. Kong et al. showed that large
portions of marine scaffolds are novel (Kong
et al. 2010). Auranomides A and B, quinazolin4-ones substituted with a pyrrolidin-2-iminium
moiety from the marine-derived fungus Penicillium aurantiogriseum, or aspergillols A and
B with a C–C fusion of an anthraquinone and
orcinol unit from a deep-sea Aspergillus versicolor represent new scaffolds from marine habitats (Song et al. 2012; Wu et al. 2016). Probably,
these compounds constitute only a small portion of the possible repertoire, as drug discovery efforts often involve a specific focus, either
on disease target, taxonomic groups or on habitats, but do not aim to describe the full genetic
biosynthetic potential.
Today, only a few compounds made their
way to the pharmaceutical market. Marine fungal compounds do face the same challenges in
drug discovery and drug development as any
other fungal compounds. However, in the
1950s, cephalosporin C, a b-lactam type natural antibiotic, was discovered from a Cephalosporium (later reclassified as Acremonium)
strain obtained at the Sardinian coast (Newton
and Abraham 1955; Abraham et al. 1953). Gliotoxin was identified as a new type of the antibiotic diketopiperazine produced by a marine
deep-sea sediment Aspergillus sp. strain (Okutani 1977).
Marine fungi did also prove to be effective
producers of natural products with antitumoral
activity (Pejin and Karaman 2017). However,
halamid, an anticancer compound of marine
fungal origin (trade name plinabulin) is the
only one already being in clinical testing
phase 2 and 3 for different indications (for
review see Pereira et al. 2019). Nevertheless,
the current chemotherapeutic clinical pipeline
will be fed with marine-derived fungal agents,
which are in preclinical stage at the moment.
A steadily increasing number of new, active
fungal natural products have been identified
from the marine environment, proving them
to be a prolific source for bioactive compounds:
Blunt et al. listed over 200 natural products
from marine-sourced fungi (excluding those
from mangroves) in the year 2013 (Blunt et al.
2015). Cosmetic and cosmeceutical applications might also be taken into account for
marine fungal secondary metabolites (Agrawal
et al. 2018). Here, biotechnological approaches
can help to close the developmental gap
between discovery and production in order to
solve compound availability issues in drug
development (as reviewed for antibiotics in Silber et al. 2016).
B. Enzymes
Marine fungi can be used for the biotechnological production of salt- and osmostable enzyme
variants but do also provide new enzymatic
activities. Fungi foster, e.g., the detrital processes by production of extracellular degradative enzymes (Sikes et al. 2009). These fungal
enzymes from marine origin can be used in
biotechnological applications. Extracellular degradative enzymes such as cellulases, xylanases,
and ligninases of several terrestrial fungi already
have found biotechnological applications in
paper and pulp industries, food production,
and clothing industry. Fungi isolated from living
and decaying marine plant material are capable
of degrading “classical” plant macromolecules,
like cellulose, cellobiose, lipids, pectin, starch,
xylan, and tannic acid (Gessner 1980). In addition, marine fungi can degrade the special carbohydrates found in marine plants, such as
alginates, sulfated polysaccharides, laminarin,
fucoidan, etc. (as early described as in Schaumann and Weide 1990). These enzymes can be
applied in transforming these sugars for energetic use of algal remaining’s (e.g., for biogas
production) especially from aquacultures. Also,
fungal polygalacturonases are useful enzymes
for clarification of fruit juices in the food industry (Sandri et al. 2011).
16 Biotechnology of Marine Fungi: New Workhorses and Applications
405