may include metabolic engineering manipulating the genetic background as a basis for generation of “biological” derivatives (Silber et al.
2016). For terrestrial fungi, the technical and
economic feasibility of large-scale processes
has been proven many times. Successful transfer into stirred-tank-reactor-system for antibiotic production from marine fungi has been
demonstrated, e.g., for the biosynthesis of the
tetramic acid compounds ascosetin and lindgomycin by an Arctic marine fungus of the Lindgomycetaceae family (Wu et al. 2015)
exhibiting a novel chemical composition.
Sarkar et al. (2010) provided bioprocess
data for fermentations of marine fungi for
enzyme production. Based on their analysis,
there is a demand for further adaptations of
scale and inclusion of knowledge on the biology
of the fungi into the design of the production
processes (e.g., salinity adaptations or pressure
for deep-sea organisms). Development of full
fermentative processes is required (Sarkar et al.
2010). The increasing knowledge gained on all
regulatory levels by means of “omics” techniques will provide the necessary insights.
Knowledge on the regulatory genes can be
applied in genetic approaches to activate natural product production. Due to the lack of
model organisms upon marine fungi, genetic
tools for heterologous expression and for
homologous manipulation of marine fungi are
still in their infancy. The recently successful
overexpression of genes leading to synthesis of
enniatins,
cyclodepsipeptides
originally
isolated from Halosarpheia sp., in Aspergillus
niger demonstrated reprogramming and transplanting of biosynthetic pathways into established models as a further tool for such
approaches (Zobel et al. 2016).
Inclusion of new methods into process
development will significantly contribute to
further improvements. The use of immobilized
cells in a repeated batch tower reactor led to a
significant increase of yield in the production of
cephalosporin (Ozcengiz and Demain 2013).
Niche-mimic bioreactors might be one opportunity to enhance productivity as well as the
development of specialized reactors in industrial scale.
VI. Conclusions
A majority of culture-dependent and cultureindependent fungi recovered from marine
resources show homology to terrestrial species,
which obfuscated the ecological role of marine
fungi. The presence of novel fungal sequences
with less than 97% similarity to previously
identified fungal sequences in public databases
and culture studies demonstrating obligate
marine culture conditions has proven the multiphyletic ecological group of marine fungi.
These fungi show unique cultivation properties and features. In nature, they fulfill a number of ecological functions, comparable to
terrestrial fungi. Their unique features may be
applied in biotechnology for new products but
also for redesign of existing biotechnological
processes with more robust culture conditions,
as marine fungi did adapt to harsh conditions
including high pressure, high osmolarity, cold,
toxic heavy metal concentrations, etc.
Only few examples of industrial processes
using marine fungi as production organisms
are available, but the number of studies highlighting the potential is impressive for enzymes,
secondary metabolites, and other possible products. Industrial-scale biotechnological processes should be feasible from scientific,
technical, and economic perspectives. This viability needs to be demonstrated through the
development of process concepts based on fermentation including metabolic engineering,
purification, molecular design, and synthesis
data. Some obstacles remain, which need to be
solved. Especially, the reduction of the salinity
in culture media is a technological challenge.
To realize the potential, we suggest to:
1. Apply products of marine fungi but also
establish new and robust workhorses in
biotechnology. The biodiversity of filamentous fungi from marine sources is mostly
untapped for these applications.
2. Bring together the different scientific communities working on marine and terrestrial
fungi and learn from existing processes.
Interdisciplinarity between technologists,
ecologists, and marine scientist will help
408
A. Kramer and A. Labes
2016). For terrestrial fungi, the technical and
economic feasibility of large-scale processes
has been proven many times. Successful transfer into stirred-tank-reactor-system for antibiotic production from marine fungi has been
demonstrated, e.g., for the biosynthesis of the
tetramic acid compounds ascosetin and lindgomycin by an Arctic marine fungus of the Lindgomycetaceae family (Wu et al. 2015)
exhibiting a novel chemical composition.
Sarkar et al. (2010) provided bioprocess
data for fermentations of marine fungi for
enzyme production. Based on their analysis,
there is a demand for further adaptations of
scale and inclusion of knowledge on the biology
of the fungi into the design of the production
processes (e.g., salinity adaptations or pressure
for deep-sea organisms). Development of full
fermentative processes is required (Sarkar et al.
2010). The increasing knowledge gained on all
regulatory levels by means of “omics” techniques will provide the necessary insights.
Knowledge on the regulatory genes can be
applied in genetic approaches to activate natural product production. Due to the lack of
model organisms upon marine fungi, genetic
tools for heterologous expression and for
homologous manipulation of marine fungi are
still in their infancy. The recently successful
overexpression of genes leading to synthesis of
enniatins,
cyclodepsipeptides
originally
isolated from Halosarpheia sp., in Aspergillus
niger demonstrated reprogramming and transplanting of biosynthetic pathways into established models as a further tool for such
approaches (Zobel et al. 2016).
Inclusion of new methods into process
development will significantly contribute to
further improvements. The use of immobilized
cells in a repeated batch tower reactor led to a
significant increase of yield in the production of
cephalosporin (Ozcengiz and Demain 2013).
Niche-mimic bioreactors might be one opportunity to enhance productivity as well as the
development of specialized reactors in industrial scale.
VI. Conclusions
A majority of culture-dependent and cultureindependent fungi recovered from marine
resources show homology to terrestrial species,
which obfuscated the ecological role of marine
fungi. The presence of novel fungal sequences
with less than 97% similarity to previously
identified fungal sequences in public databases
and culture studies demonstrating obligate
marine culture conditions has proven the multiphyletic ecological group of marine fungi.
These fungi show unique cultivation properties and features. In nature, they fulfill a number of ecological functions, comparable to
terrestrial fungi. Their unique features may be
applied in biotechnology for new products but
also for redesign of existing biotechnological
processes with more robust culture conditions,
as marine fungi did adapt to harsh conditions
including high pressure, high osmolarity, cold,
toxic heavy metal concentrations, etc.
Only few examples of industrial processes
using marine fungi as production organisms
are available, but the number of studies highlighting the potential is impressive for enzymes,
secondary metabolites, and other possible products. Industrial-scale biotechnological processes should be feasible from scientific,
technical, and economic perspectives. This viability needs to be demonstrated through the
development of process concepts based on fermentation including metabolic engineering,
purification, molecular design, and synthesis
data. Some obstacles remain, which need to be
solved. Especially, the reduction of the salinity
in culture media is a technological challenge.
To realize the potential, we suggest to:
1. Apply products of marine fungi but also
establish new and robust workhorses in
biotechnology. The biodiversity of filamentous fungi from marine sources is mostly
untapped for these applications.
2. Bring together the different scientific communities working on marine and terrestrial
fungi and learn from existing processes.
Interdisciplinarity between technologists,
ecologists, and marine scientist will help
408
A. Kramer and A. Labes