Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
Laccase (EC 1.10.3.2) belongs to a group of enzymes
called blue copper oxidases which uses oxygen as electron
acceptor to remove hydrogen from phenolic hydroxyl
groups. This reaction leads to the formation of free radicals
that can undergo rearrangements leading to alkyl-aryl
cleavage, oxidation of benzyl alcohols, and cleavage of
side chains and aromatic rings. Presently of great interest is
the examination of laccase in relation to the possibility of
enzyme applications in biotechnology in particular for pulp
biobleaching. The main limitation of laccase-mediator
system application is very high dosage of laccase and redox
mediator needed for pulp beableaching or detoxification
processes. In order to overcome this factor it is necessary to
investigate the mechanism of lignin degradation, the
interaction between lignolytic enzymes and especially their
synergism during lignin degradation. The two strains
Cerrena maxima and Coriolus hirsutus producing high
yield of extracellular Mn-peroxidase and laccase under cocultivation
have been found. It was shown that both C.
maxima and C. hirsutus produced three isoenzymes pI
3.53, 3.91, 4.25 and 3.6, 4.0, 4.5, respectively. However,
during co-cultivation of these strains, only one laccase
isoenzyme pI 4.0 has been produced. The physico-chemical
properties and N-terminal amino acid sequence of this
isoenzyme have been studied in comparison with
isoenymes produced by pure fungal cultures of C. maxima
and C. hirsutus.
1132 - Aquatic hyphomycetes living under heavy metal
stress
G.-J. Krauss 1* & G. Krauss 2
1 Martin-Luther University, Dept.
Biochemistry/Biotechnology, Div. Ecology and Plant
Biochemistry, K. Mothes Str.3, D-06099 Halle/Saale,
Germany. - 2 Microbiology of Subterrestrial Aquatic
Systems Group, UFZ Centre for Environmental Research,
Leipzig-Halle, Theodor -Lieser -Str. 4, D-06120
Halle/Saale, Germany. - E-mail: krauss@biochemtech.unihalle.de
In a former copper shale mining district in Central
Germany, weathering of slag heaps and dumps resulted in
groundwater, lakes and streams with extremely high heavy
metal and metalloid concentrations. Communities of
aquatic hyphomycetes (AQH) in such streams are clearly
impoverished but still surprisingly diverse, and leaf
decomposition and conditioning proceeds even [1, 2].
Crystalline components form a crust over the developing
fungal biofilms. Two strains of Heliscus lugdunensis
isolated from a harsh and a moderately polluted habitat
respectively, had clearly adapted to these conditions.
Conidia of both strains are significantly distinct in shape
and size. Their capacity for biosorption and accumulation
of Cd(II) and Cu(II) in liquide culture was quite different.
Under Cd stress both strains showed specific response in
their production and turnover of glutathione (GSH) and
sulfur-rich peptides. Both strains synthesized significantly
more GSH in the presence of Cd ranging from 25 µM to
100 µM, but quantitiy and time course were different. It
seems likely that resistant AQH have undergone
considerable physiological and genetic changes. [1]
KRAUSS, G. et al. (2001) Aquatic hyphomycetes occur in
hyperpolluted waters in Central Germany. Nova Hedwigia
72: 419-428 [2] SRIDHAR, K.R. et al. (2001)
Decomposition of alder leaves in two heavy metal polluted
streams in Central Germany. Aquatic Microbial Ecology,
26: 73-80.
1133 - Diversity of genome size in zygotic meiosis of
Pleurotus studied by flow cytometry
B. Kullman
Institute of Zoology and Botany, Estonian Agricultural
University, 181 Riia Str., 51014 Tartu, Estonia. - E-mail:
bellis@zbi.ee
For quantitative evaluation of nuclear DNA and protein
contents of spores, the flow cytometer (PAS) with staining
DAPI SR101 was employed. The spore print of P.
ostreatus (TAA 142824) is applicable as a standard
(24Mb). The spore nuclei of P. ostreatus are unreplicated
(Kullman, 2000). Two spore prints collected from wild (PV
and PU) fruitbodes and one from a commercial (PM)
fruitbody were studied. Two subpopulations were
discovered in the spore print of PM and in PU and one in
PV. The diversity of a spore print reflect the fate of hybrid
genomes during meiosis. The spores of PM are divided in
to two equally represented groups. One of them has the
smallest DNA and protein content per spore compared with
wild mushrooms. At the same time, these characters,
especially protein content, are more variable. It can be
suggested that in meiosis two hybrid genomes be divided.
They differ 1.5 times in DNA content and 4.1 times in
protein content, which corresponds to the loss of many
chromosomes. Different chromosome numbers and
genome sizes reported by several authors for one and the
same species may also refer to the existence of a true
aneuploidy indicating the plasticity of the fungal genome.
Meiosis can occur even in the case of low density of
homology between chromosomes (CLP and aneuploidy)
and may ensure distribution of highly different strains. If in
the zygote two nuclei are only a little conjugated than their
mitotic haploidisation may results in dimorphism of spores.
1134 - Isolation and characterization of thermophilous
fungi from temperate soil of north India
R. Kumar
Guru Nanak Dev University, Department of Botanical and
Environmental sciences, Guru Nanak Dev University,
amritsar - 143 005, India. - E-mail:
rajsalar@rediffmail.com
Thermophilic fungi are now a well-recognised group for
their temperature relationships, taxonomic characterization,
industrial application and for wide occurrence. In the
present study 19 species of thermophilic and
thermotolerant fungi belonging to 14 genera were isolated
Book of Abstracts 343