Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
promoter (alcA(p)-chsB). Under repressing condition, the
mutant exhibited similar phenotypes to those of the chsB
disruptant. To examine the functional relationships of other
chitin synthase genes with chsB, we constructed three types
of double mutants in which the chsA, chsC, or chsD
deletion mutation was combined with alcA(p)-chsB. The
chsD chsB double mutants grew more slowly than the chsB
single mutant under high osmolarity conditions. The
hyphae of the double mutants appeared to be more
disorganized than those of the chsB single mutant. These
results indicate the importance of the ChsD function in the
absence of chsB expression. The chsA chsB and chsC chsB
double mutants also showed different phenotypes from the
chsB single mutant under alcA(p)-repressing conditions;
the chsA chsB double mutant produced less aerial hyphae,
and the chsC chsB double mutant showed reduced cell
mass. These observations suggest that chsA and chsC each
play some different roles in hyphal morphogenesis.
1122 - Effect of the wood degrading basidiomycete
Coniophora puteana on the chemical and physical
properties of pinewood
I. Irbe * , B. Andersons & J. Chirkova
Latvian State Institute of Wood Chemistry, 27 Dzerbenes
St., Riga, LV 1006, Latvia. - E-mail: ilzeirbe@edi.lv
Coniophora puteana is a wood destroying basidiomycete,
widespread both in nature and construction wood. The
fungus produces a brown-rot in soft- and hardwood,
primarily degrading its polysaccharides, while lignin is
only modified. The fungus is often encountered in the
buildings in Latvia, causing considerable damage to wood
in service. The aim of this study was to investigate the
chemical, physical and ultrastructural changes in the
pinewood degraded by C. puteana (Schum.:Fr.) Karst.
(BAM Ebw.15) isolate. For this, the Scots pine sapwood
blocks were subjected to the attack of fungus for 4 months
in laboratory conditions. Decayed wood was analyzed by
ion exchange chromatography, water vapor sorption and
scanning electron microscopy (SEM) methods. At the
wood weight loss of 40%, the losses of hemicelluloses
forming monosaccharides mannose and galactose were
78% and 56%, while xylose and arabinose were lost by
47% and 39%, respectively. The losses of cellulose
forming monosaccharide, glucose, comprised 32%. Based
on the water sorption isotherms, value of the accessible
specific surface A, and constant am, characterizing the
mass hydrophilicity, were determined. Correlation between
the value A and wood weight losses was obtained. The
hydrophilicity am tended to decrease as the share of lignin
in decayed wood increased. SEM micrographs illustrated
the pattern of thinning and cracking of the wood cell wall,
confirming the considerable loss of wood carbohydrates.
1123 - Solubilization of metal phosphates by fungi as a
consequence of carbon translocation
340
Book of Abstracts
H. Jacobs 1* , G.P. Boswell 2 , K. Ritz 3 , F.A. Davidson 2 &
G.M. Gadd 1
1 Division of Environmental and Applied Biology,
Biological Sciences Institute, School of Life Sciences,
University of Dundee, Dundee, DD1 4HN, Scotland, U.K. -
2 Department of Mathematics, University of Dundee,
Dundee, DD1 4HN, Scotland, U.K. - 3 Soil-Plant Dynamics
Group, Scottish Crop Research Institute, Invergowrie,
Dundee, DD2 5DA, Scotland, U.K. - E-mail:
h.jacobs@dundee.ac.uk
The spatial distribution of nutrients in most soils is
heterogeneous due to factors that include soil type and
structure. Pollutants, such as toxic metal-contaminated
wastes, and soil amendments such as fertilizers, also
increase the heterogeneity of the edaphic environment. The
ability of fungi to solubilize insoluble metal phosphates, by
the production of organic acids, is important for both plant
and microbial nutrition. Whilst filamentous fungi are well
adapted for growth in heterogeneous conditions,
experimental information in relation to the functional
consequences of such phenomena is sparse. A model
system consisting of concentric rings of discrete agar
droplets was developed which allowed study of fungal
growth in vitro in nutritionally-heterogeneous conditions.
Droplets containing different combinations of glucose and
calcium phosphate were used to study the consequences of
spatially separating these components in relation to metal
phosphate solubilization by Rhizoctonia solani. In the
presence of the fungus, solubilization of calcium phosphate
only occurred when glucose was present in the underlying
medium. However, solubilization occurred in droplets
containing calcium phosphate, but no glucose, when
glucose was present in other droplets within the tessellation
and where fungal hyphae spanned the droplets. This
demonstrates that substrate was transported via mycelia
from glucose-containing domains, with the functional
consequence of metal phosphate solubilization.
1124 - Modulation of phospholipid metabolism in
cAMP-dependent protein kinase mutants of Aspergillus
niger
K. Jernejc * & M. Bencina
National Institute of Chemistry, Hajdrihova 19, SI-1000
Ljubljana, Slovenia. - E-mail: katarina.jernejc@ki.si
Cyclic AMP-dependent protein kinase (PKA) plays a
crucial role in the regulation of metabolic pathways by
means of enzyme phosphorylation and therefore in changes
of the activities of key cellular enzymes. Genes encoding
PKA catalytic and regulatory subunits in Aspergillus niger
were cloned, characterized, overexpressed and/or deleted.
The correlation between cAMP-dependent protein kinase
activity and phospholipid biosynthesis in wild type A. niger
strain and strains with overexpressed and deleted genes for
regulatory pkaR and/or catalytic pkaC subunit was
followed. Isolated mutants displayed different lipid,
especially phospholipid metabolism. In mutant strains with
abolished PKA activity amount of total lipids was 1.6 times
higher, with much more neutral lipids than in other mutant