cell biology and feeding strategies and partly
because of the bias of research (Richards et al.
2012). However, the number of isolated fungal
strains from the marine environment illustrates
the presence of marine fungi. They have been
found in association with algae (Raghukumar
2006), sponges (Wiese et al. 2011), and corals
(Golubic et al. 2005), as well as in deep-sea mud
(Takami et al. 1997, Nagahama 2003) and sediments (Damare et al. 2006), even in anoxic
(Stoeck et al. 2003) and methane hydratebearing deep-sea sediments (Lai et al. 2007).
Living fungi were isolated from marine sediments with an estimated age from 0.18 to 0.43
million years (Gupta 2002, Raghukumar et al.
2004b). In 1979, Kohlmeyer and Kohlmeyer
distinguished between two groups of marine
fungi, i.e., the obligate and the facultative
marine fungi (Kohlmeyer and Kohlmeyer
1979). Due to the fact that many taxa isolated
from marine habitats are already known from
terrestrial habitats, Hyde et al. stated marine
fungi to be rather a physiological and ecological group, but certainly not a systematical and
taxonomical one (Hyde et al. 2000).
Recent molecular studies on marine mycology revealed the formation of environmental
clusters within the major fungal phyla and
showed that marine fungi occupy a central
position in a large number of marine habitats
(Manohar and Raghukumar 2013). The rising
acceptance of the significance of marine fungi is
reflected by the increasing number of publications over the last 60 years. To enhance the
currently incomplete understanding of fungal
evolutionary diversity (Hawksworth 2001;
Jones 2011; Jones et al. 2011), the investigation
of the fungal evolution in marine habitats, especially in the deep sea, is essential. These habitats are considered to be hot spots of early
evolution (Manohar and Raghukumar 2013).
In the past, the identification of novel
strains from marine habitats was impeded by
fungal taxonomy based on the morphological
description of cultivable strains from terrestrial
origin (Richards et al. 2012). Nowadays, the use
of additional molecular identification techniques has led to a renewal within the fungal
tree of life. Holomorphic relationships were
disclosed, as for the genus Aspergillus and
eight related teleomorph genera (Pitt and Samson 2007), illustrating the obscurity of the
nomenclature of fungi.
In 2011, the eighteenth International Botanical Congress in Melbourne, Australia, released
the International Code of Nomenclature for
algae, fungi and plants, the so-called Melbourne
Code (Hawksworth 2011). The code favors the
one-fungus-one-name-rule, with respect to the
teleomorph forms. Besides the deficient
nomenclature within the group of fungi, the
reconstruction of the tree of life refuted the
formerly assumed close relationship of fungi
and plants. Fungi are an independent group
equal to plants and animals, to the latter of
which they are more closely related (Hedges
et al. 2004) as both groups belonging to the
Opisthokonta (Adl et al. 2012). The last common ancestor was a unicellular organism living
in the ocean, equipped with a flagellum (Buckley 2008). Molecular data revealed that fungi
colonized the land up to 1 billion years ago
(Parfrey et al. 2011).
Metagenomics approaches identified a
diverse collection of marine fungi, including
sequences branching close to chytrids (flagellated protozoa related to fungi), filamentous
hypha-forming fungi, and multicellular fungi.
The majority of the sequences branched with
ascomycete
and
basidiomycete
yeasts
(Richards et al. 2012).
With respect to the cultivated diversity, the
availability of novel marine genera is still limited. From a total of approximately 30 studies
on secondary metabolites from fungi of the
deep sea, one-third of the production strains
were identified as belonging to Penicillium
and one-third to Aspergillus, and the remainder
was distributed to different other genera (Wang
et al. 2015). The high proportion of members of
the genera Penicillium and Aspergillus may
reflect the high abundance of representatives
of these two genera in the samples. Alternatively, the commonly used isolation media
favor the growth of these fast-growing groups,
reducing the probability to isolate fungi present
in low abundance and with other nutrient
requirements.
400
A. Kramer and A. Labes
because of the bias of research (Richards et al.
2012). However, the number of isolated fungal
strains from the marine environment illustrates
the presence of marine fungi. They have been
found in association with algae (Raghukumar
2006), sponges (Wiese et al. 2011), and corals
(Golubic et al. 2005), as well as in deep-sea mud
(Takami et al. 1997, Nagahama 2003) and sediments (Damare et al. 2006), even in anoxic
(Stoeck et al. 2003) and methane hydratebearing deep-sea sediments (Lai et al. 2007).
Living fungi were isolated from marine sediments with an estimated age from 0.18 to 0.43
million years (Gupta 2002, Raghukumar et al.
2004b). In 1979, Kohlmeyer and Kohlmeyer
distinguished between two groups of marine
fungi, i.e., the obligate and the facultative
marine fungi (Kohlmeyer and Kohlmeyer
1979). Due to the fact that many taxa isolated
from marine habitats are already known from
terrestrial habitats, Hyde et al. stated marine
fungi to be rather a physiological and ecological group, but certainly not a systematical and
taxonomical one (Hyde et al. 2000).
Recent molecular studies on marine mycology revealed the formation of environmental
clusters within the major fungal phyla and
showed that marine fungi occupy a central
position in a large number of marine habitats
(Manohar and Raghukumar 2013). The rising
acceptance of the significance of marine fungi is
reflected by the increasing number of publications over the last 60 years. To enhance the
currently incomplete understanding of fungal
evolutionary diversity (Hawksworth 2001;
Jones 2011; Jones et al. 2011), the investigation
of the fungal evolution in marine habitats, especially in the deep sea, is essential. These habitats are considered to be hot spots of early
evolution (Manohar and Raghukumar 2013).
In the past, the identification of novel
strains from marine habitats was impeded by
fungal taxonomy based on the morphological
description of cultivable strains from terrestrial
origin (Richards et al. 2012). Nowadays, the use
of additional molecular identification techniques has led to a renewal within the fungal
tree of life. Holomorphic relationships were
disclosed, as for the genus Aspergillus and
eight related teleomorph genera (Pitt and Samson 2007), illustrating the obscurity of the
nomenclature of fungi.
In 2011, the eighteenth International Botanical Congress in Melbourne, Australia, released
the International Code of Nomenclature for
algae, fungi and plants, the so-called Melbourne
Code (Hawksworth 2011). The code favors the
one-fungus-one-name-rule, with respect to the
teleomorph forms. Besides the deficient
nomenclature within the group of fungi, the
reconstruction of the tree of life refuted the
formerly assumed close relationship of fungi
and plants. Fungi are an independent group
equal to plants and animals, to the latter of
which they are more closely related (Hedges
et al. 2004) as both groups belonging to the
Opisthokonta (Adl et al. 2012). The last common ancestor was a unicellular organism living
in the ocean, equipped with a flagellum (Buckley 2008). Molecular data revealed that fungi
colonized the land up to 1 billion years ago
(Parfrey et al. 2011).
Metagenomics approaches identified a
diverse collection of marine fungi, including
sequences branching close to chytrids (flagellated protozoa related to fungi), filamentous
hypha-forming fungi, and multicellular fungi.
The majority of the sequences branched with
ascomycete
and
basidiomycete
yeasts
(Richards et al. 2012).
With respect to the cultivated diversity, the
availability of novel marine genera is still limited. From a total of approximately 30 studies
on secondary metabolites from fungi of the
deep sea, one-third of the production strains
were identified as belonging to Penicillium
and one-third to Aspergillus, and the remainder
was distributed to different other genera (Wang
et al. 2015). The high proportion of members of
the genera Penicillium and Aspergillus may
reflect the high abundance of representatives
of these two genera in the samples. Alternatively, the commonly used isolation media
favor the growth of these fast-growing groups,
reducing the probability to isolate fungi present
in low abundance and with other nutrient
requirements.
400
A. Kramer and A. Labes