Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
1150 - Ecophysiological manipulation of fermentation
improves viability of the biocontrol yeast Pichia
anomala
S. Mokiou * & N. Magan
Applied Mycology Group, Biotechnology Centre, Cranfield
University, Silsoe, Bedford MK45 4DT, U.K. - E-mail:
s.mokiou.s00@cranfield.ac.uk
For effective biocontrol to be achieved it is important that
cheap and economic substrates can be used to produce
ecologically competent inocula. To this end we have
examined and compared the production of the biocontrol
yeast P. anomala on rich defined media (NYDB) and on
molasses. Manipulation of the physiology of the yeast by
modification of water stress [water activity (aw) of 0.98 and
0.96] using different compatible solutes/sugars and NaCl
markedly affected yield and quality of the cells.
Endogenous water potential of cells, and sugar/sugar
alcohol contents were significantly modified.In general,
accumulation/synthesis of trehalose or sugar alcohols was
affected by the solute used in media. For example, use of
proline, glucose and sorbitol in molasses-based media
resulted in accumulation of the desiccation protectant
trehalose, while proline, NaCl, glucose, sorbitol and
glycerol in media resulted in an accumulation/synthesis of
glycerol and varying amounts of arabitol. Ecological
competence of the yeast treatments was examined by
plating on non-stressed (0.995 aw) and water stressed media
(0.96 a w). Viability was significantly improved by the use
of some solutes in molasses-based media. Such studies
have implications for improving shelf-life and perhaps the
production of ecologically stable biocontrol agents.
1151 - Identification of mating type sequences in
toxigenic Fusarium species known as asexual fungi
A. Moretti 1* , Z. Kerényi 2 , G. Mulè 1 , C. Waalwijk 3 & L.
Hornok 2
1 Institute of Science of Food Production (CNR), Viale
Einaudi, 51, Bari, Italy. - 2 Agricultural Biotechnology
Center, P.O. box 16, Szebet-Gyorgy 4, 2100 Godollo,
Hungary. - 3 Plant Research International, Business Unit
Biointeractions and Plant Health, P.O. box 16, 6700 AA,
Wageningen, The Netherlands. - E-mail:
moretti@area.ba.cnr.it
Fusarium species currently known as asexual fungi showed
to possess mating type (MT) sequences similar to those of
species in which sexual recombination regularly occurs.
Two pairs of degenerated oligonucleotide primers based on
known fungal MT sequences were designed. Each of the
two conserved MT sequences, ALPHA- and HMG-boxes,
could be detected by PCR in F. camptoceras, F. cerealis,
F. culmorum, F. poae, F. langsethiae, F. semitectum, F.
sporotrichioides, F. redolens and F. oxysporum. Sizes of
MAT-1 and MAT-2 amplicons were 200 bp, and 260 bp
long. Both MAT-1 and MAT-2 sequences were identified
for all species, but F. camptoceras (MAT-2) and F.
langsethiae (MAT-1) for which just one MT was detected.
As the sexual behaviour of F. avenaceum is not clear, this
fungus was also studied. No strain of F. avenaceum was
found to harbour both MT sequences, although it has been
reported as weak homothallic species. On the other hand
both MAT-1 and MAT-2 sequences occurred in single
strain of F. graminearum, a typical homothallic species.
RT-PCR experiment was set up to find the transcription of
MAT genes in F. avenaceum, F. culmorum, F. poae and F.
sporotrichioides. By using the primers pairs,
fusALPHAfor/fusALPHArev and fusHMGfor/fusHMGrev,
one characteristic PCR amplicon was produced in all
samples, indicating that MT genes are transcribed in all
asexual Fusarium strains included in these experiments.
Support of EU Fifth Framework (Detox fungi QLK1-CT-
1999-001380).
1152 - Analysis of CHS8 - a fourth chitin synthase
isoenzyme of Candida albicans
C.A. Munro, R.K. Adam, H.B. Hughes * , S. Selvaggini, M.
Reilla & N.A.R. Gow
Department of Molecular and Cell Biology, Institute of
Medical Sciences, Foresterhill, Aberdeen, AB25 2TP,
Scotland, U.K. - E-mail: b.hughes@abdn.ac.uk
All fungi studied to date have multigene families of chitin
synthase enzymes. In the dimorphic pathogen Candida
albicans, three genes encoding chitin synthases have
previously been identified. CHS1 encodes a chitin synthase
involved in primary septum formation and is essential for
viability. CHS2 is not essential for viability, but is
responsible for the majority of chitin synthase activity
detectable in vitro. CHS3 is responsible for producing most
of the chitin present in both yeast and hyphal cell walls,
and deletion of the gene results in attenuation of virulence.
Recently a fourth chitin synthase gene CHS8 encoding a
second class I enzyme was identified in the genome
sequence. The chs8 null mutant was more sensitive to
certain agents disruptive to cell wall integrity, had a
significant reduction in the in vitro hyphal chitin synthase
activity and a slight reduction in hyphal chitin content.
Microsomal preparations of chs2/chs8 double mutant had
very low chitin synthase activity but the organism had
normal morphology. Class I enzymes are therefore
dispensable for normal growth of this organism.
1153 - Cloning of chitin deacetylase gene from
Phycomyces blakesleeanus and its expression in
Escherichia coli
T. Murayama 1* , A. Miyazaki 2 & K. Imamura 1
1 College of Engineering, Kanto-Gakuin Univ., 1-50-1
Mutsu-ura Higashi, Kanazawa-ku, Yokohama 236-8501,
Japan. - 2 Graduate School of Life Sciences, Tohoku
University, Katahira, Aoba-ku, Sendai 980-8577, Japan. -
E-mail: murayama@kanto-gakuin.ac.jp
Book of Abstracts 349