Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
aggregates. To cast further light on molecular mechanisms
of this copper-philicity, differential protein expression
analyses were performed, resulting in different protein
profiles between mycobiont aggregates cultured with and
without copper ion.
1115 - Determining the relative role of ligand versus
proton-promoted dissolution of metal phosphates by
fungi
F.A. Harper * & G.M. Gadd
Department of Environmental and Applied Biology,
University of Dundee, Biological Sciences Institute,
Dundee, DD1 4HN, Scotland, U.K. - E-mail:
f.a.harper@dundee.ac.uk
Many soil fungi can solubilize sparingly soluble metal
phosphates, and are thus important agents in nutrient
cycling of phosphate and metal ions. Despite rapid
screening methods to identify isolates with proficient
phosphate solubilizing activity, there lacks quantitative
data on the mechanisms by which dissolution occurs. Two
non-mutually exclusive mechanisms involving efflux of (i)
protons and/ or (ii) metal complexing ligands (such as
organic acid anions) are frequently acknowledged in this
role, although their relative importance in the dissolution
process is unclear. In this work we used Aspergillus niger,
Fusarium sp. and Coriolus versicolor, to develop
contrasting models to provide a better mechanistic
understanding of phosphate dissolution. We show that the
relative role of proton versus ligand-promoted dissolution
is influenced by many factors, including nitrogen-source,
with marked differences occurring between fungal species.
Many fungi subsequently immobilize metals, such as
recrystallization as oxalates, while all fungi exhibit surface
sorption and/or intracellular accumulation. Similar to the
mechanisms of mobilization, these lack proper
quantification. A sequential extraction technique has been
used to fractionate metal in fungal biomass and agar into
soluble, phosphate and oxalate phases, in order to quantify
the fate of metal and achieve a mass balance. The
functional significance of our findings for fungi in
biogeochemical processes will be discussed.
1116 - Production of neutral and alkaline proteases by
the thermophilic fungus, Scytalidium thermophilum,
grown on microcrystalline cellulose
I. Hasbay Ifrij * & Z.B. Ogel
Middle East Technical University, Department of Food
Engineering, 06531 Ankara, Turkey. - E-mail:
incinur@metu.edu.tr
Scytalidium thermophilum protease production in Avicelcontaining
media was analysed. Proteases produced by
Scytalidium thermophilum were found to be most active at
neutral and alkaline pH and at a temperature range of 37-45
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Book of Abstracts
°C. Highest protease activity was observed at early
exponential phase where endoglucanase activity was low.
The production of proteases and endoglucanases on
different days suggested a possible negative effect of
proteases on endoglucanase activity. The effect of protease
inhibitors were examined to determine the type of
proteases. Those were pCMB, antipain, PMSF, E-64,
EDTA and pepstatin A. Antipain, pCMB and PMSF were
observed to be effective on proteases produced by the
fungus. Two major protease inhibition peaks at day 3 and 5
suggest production of thiol-containing serine protease and
serine protease, respectively. The presence of protease
inhibitors in culture medium or cell-free supernatants failed
to show a significant effect on endoglucanase activity and
the ability of endoglucanases to adsorb onto Avicel.
1117 - Development of an Aspergillus sojae expression
system
M. Heerikhuisen * , A. Drint-Kuyvenhoven, A.R. Albers,
C.A.M. van den Hondel & P.J. Punt
TNO Nutrition and Food Research Institute, Utrechtseweg
48, Zeist 3704 HE, The Netherlands. - E-mail:
Heerikhuisen@voeding.tno.nl
Aspergillus species are known as high-level expression
hosts for the production of enzymes or metabolites. In the
last two decades for the industrially used species for
Aspergillus niger, A. foetidus, A. tubigensis, and A. oryzae
expression systems have been developed. We describe the
development of an expression system based on the koji
mold Aspergillus sojae for the production of homologous
and heterologous proteins. Transformation based on
auxotrophic (pyrG, niaD) and/or dominant markers
(amdS), was used to introduce the genes of interest. To
improve the yield of produced protein, Aspergillus sojae
mutants with lower protease activity, either by gene
disruption or by UV mutagenesis, were isolated. To
improve the fermentation yields of Aspergillus sojae also
morphological and so-called fermentor adapted mutants
with lower viscosity, were isolated. As one of the examples
for heterologous protein production, the production of
human interleukin 6 was used. References: Heerikhuisen,
M. et al. (2001) World Patent Application WO 01/09352.
1118 - Isolation, structure elucidation and biological
activities of novel secondary metabolites from Pochonia
chlamydosporia (Goddard) Zare & W. Gams
V. Hellwig 1 , A. Mayer-Bartschmid 1 , W. Zitzmann 1 , G.
Greif 2 , H.V. Tichy 3 , G. Kleymann 1 & M. Stadler 1*
1 Bayer AG, Pharma Research, Bayer Pharma Research
Center, P.O.B. 10 17 09, D-42115 Wuppertal, Germany. -
2 Bayer AG, Animal Health Research & Development,
Bayer AG, Research Center Monheim, Bldg. 6700, D-
51368 Leverkusen, Germany. - 3 TUEV ISB, Engesserstr.
4b, C-79108 Freiburg, Germany. - E-mail:
marc.stadler@t-online.de