TY - JOUR
AU - Deák, Tibor
AB - The 11th International Congress on Yeasts (ICY 2004) was held at Hotel Gloria, in Flamengo located at the edge of dowtown Rio de Janeiro, in a nice venue providing an elegant setting and an atmosphere of the turn-of-the-nineteenth century, recalling in certain parts the much earlier colonial style and splendour. The Congress ran from 15th to 20th of August, late winter in Brazil, and many of the participants from countries of the Northern Hemisphere were just envious of the average temperature of 25 °C for this season. The conference started on Sunday afternoon with some delay in the opening ceremony, due to the late arrival of some authorities, but after this little “magnana” all the forthcoming sessions went smoothly close to schedule. Some speakers exceeded their time, complicating attendance at presentations in parallel sessions. The daily program ran according to this scheme: a morning plenary lecture was followed by two symposia in parallel sessions and continued after the lunch break with respective poster sessions. In the afternoon, another plenary lecture and two parallel sessions for oral presentation were held. As a tradition for ICYs, the program covered all aspects of yeast science from taxonomy and phylogeny, metabolism and regulation, genetics and genomics, ecology and biodiversity, fermentations and biotechnology, to pathogenicity and interactions. However, as it could be expected for a conference in Brazil where environmental issues play a prominent role, and where a huge amount of ethanol is fermented from sugar cane, two topics emerged prominently from the program: yeast diversity and biotechnology. Opening lecture.Biotechnology and genetics was the subject of the opening lecture (Plenary lecture 1) presented by Thom Jeffries (University of Wisconsin, Madison, USA). Genes for xylose assimilation have been successfully engineered into Saccharomyces cerevisiae but the use of this substrate was hindered under anaerobic conditions. Genome-wide expression analysis revealed a complex regulatory mechanism to control gene expression in cells grown on xylose in the presence of oxygen. It remains for further research to develop a strain of S. cerevisiae with the ability to assimilate and ferment xylose effectively. Plenary lecture 2 on Yeasts as cell factories for production of chemicals and pharmaceuticals, preceded the first symposium. In his lecture, Hans van Dijken (Delft University of Technology, The Netherlands) described the wide range of possible uses of yeasts for biotechnological production of chemicals, pharmaceuticals, proteins and other polymers, either by native strains or as recombinant cells of various species. Great promise lies in yeasts' ability to grow on non-traditional carbon sources under harsh conditions, but the sustainability of the processes remains to be proven. Symposium 1 on Yeast metabolism and regulation comprised six papers. Andrei Sibirny exposed the use of the methylotrophic yeast, Hansenula polymorpha, for the production not only of fuel ethanol from xylose and cellobiose, but also of heterologous proteins, and, as whole cells, sensor bioelements. Charles Abbas discussed the industrial application of “non-conventional” yeasts such as methylotrophic, oleophilic and saccharolytic species. Peter Biely gave an overview of the enzymology and regulation of utilization of plant polysaccharides by the yeast-like fungus, Aureobasidium pullulans. Other yeast-like organisms, Tremella species, were the subject of the paper by Erick Vandamme, for the production of bioactive exopolysaccharides (capsular materials). Monique Bolotin-Fukuhara discussed the balance between regulation and fermentation in yeasts on the example of regulatory Hap4 proteins. Anita Panek dealt with the antioxidant defense system of S. cerevisiae against the reactive oxygen species formed during dehydration of the cells. The parallel Symposium 2 on Monday morning was entitled Yeast taxonomy and evolution. Though the related plenary lecture was to be read by C. Kurtzman on the next morning, six oral papers on the subject were presented this time. Ann Vaughan-Martini surprised the audience with exposing the controversy and uncertainties around the cornerstone of taxonomy, the type strain. In the case of yeasts, this concept denotes the name of a taxon but is less associated with the typical characteristics of a species and still less of a genus. Jacobus Albertyn presented evidence for the phylogenetic standing of Lipomycetaceae based on the analysis of the D1/D2 domain of the 26S rDNA gene. Diego Libkind suggested on the basis of morphological, physiological and sequence properties that isolates from Pathagonian habitats may represent a new species of the genus Phaffia. Two papers dealt with the classification and identification of Taphrina; Alfredo Fonseca gave a broad overview on the genus, whereas Hansjörg Prillinger focused on separation of certain species found on alder. In the last paper of the symposium, Vincent Robert demonstrated the highly sophisticated database developed for yeasts at the CBS culture collection. The poster sessions 1 and 2 on Metabolism and Taxonomy comprised 23 and 9 posters, respectively. In the metabolism session several posters dealt with responses of yeasts against stress factors such as oxidative, ethanol, metal and freezing. Helena Albergaria showed that S. cerevisiae causes death of other yeasts in wine by factors other than ethanol or killer toxins; James du Preez demonstrated the complex regulation of alcohol dehydrogenases upon transition from glucose to ethanol as carbon and energy source; whereas Silvia Moreno focused on the regulation from the opposite direction, from respiratory to fermentative metabolism; Albert Mas reported about the nitrogen catabolite repression under wine fermentation. Out of the taxonomy posters, mention should be made of Jack Fell presenting a new method, electrochemical detection of DNA for identifying and discriminating yeast species; Neza Cadez showing that EF1 α and actin genes provided greater resolution than rDNA regions for the classification of Hanseniaspora/Kloeckera; Andrea Pulvirenti also demonstrating the limits of rRNA-NTS2 region for the discrimination of Saccharomyces species; Mathias Sipiczki demonstrated viable interspecific hybrids between S. uvarum and S. cerevisiae; Gábor Péter found the ascosporic state of Candida kofuensis that represents a new Metschnikowia species; Leda Mendonça-Hagler characterized the ascomycetous yeasts occurring in the maize rhizosphere, with the abundance of Torulaspora delbrueckii, Debaryomyces hansenii and Pichia guilliermondii; Ilona Pfeiffer described the mitochondrial genome organization in Nadsonia fulvescens var. elongata. Plenary lecture 3 by Dieter Söll (Yale Univ., USA) gave a broad overview of Protein synthesis in the living world, with specific emphasis on the wide diversity observed for aminoacyl-tRNA formation. This lecture was followed by two parallel sessions on Genetics and genomicsas well as on Fermentation, six oral presentations each. Two main topics were discussed: recent advances in yeast genetics, and application of genetics in classification. James Cregg gave an account on the progress in sequencing the genome of Pichia pastoris, a yeast widely used in the production of recombinant proteins. It is estimated that the 9.42-Mb genome of P. pastoris contains about 6000 genes, similar to that of S. cerevisiae. Genome-wide transcription analysis was applied to improve xylose utilization in recombinant S. cerevisiae strains, as described by Marie Jeppson. Philippe Morello used DNA microarrays to map trait loci in wine strains of S. cerevisiae, whereas Eiko Kuramae gave an overview on a research project in CBS on the analysis of complete fungal genomes, using clusters of orthologous groups of proteins (called KOGs) for constructing phylogenetic trees. Genetic and molecular approaches alike have been used to shed light on the complex relation between Saccharomyces sensu stricto species as well as in the family of Saccharomycetaceae, as interpreted by Gennadi Naumov and Eladio Barrio, respectively. Application of genetics for strain improvement was the subject of several papers in the fermentation session, too. Paul Attfield described the use of high-throughput techniques to enhance screening of strains obtained by traditional genetic strategies. Matti Korhola gave an example of the application of molecular genetics to characterize sour dough yeast, Candida milleri, and Isabel Spencer-Martins dealt once more with xylose fermentation by recombinant S. cerevisiae strains. Three more papers in this session were devoted to the identification and characterization of yeasts involved in the fermentation of grapes, cocoa beans and indigenous foods by Andrea Skelin-Vujic, Lene Jespersen, and Rosane Schwan, respectively. Plenary lecture 4, given by Cletus Kurtzman (USDA-ARS, Peoria, IL, USA)on the Evolutionary relationships among ascomycetous yeasts was to start the second day of ICY 2004. Tremendous advances have been achieved in the classification of yeasts by using the analysis of the D1/D2 domain of 26S rDNA, although this approach cannot reveal evolutionary relationships in each case. Hence, multigenic analyses are needed to recognise and resolve clades of closely-related species. Examples were presented on the results of multigene analysis of species in the Saccharomyces, Stephanoascus and Pichia complexes. One of the highlights of the Congress was the Symposium 3 on Yeast diversity and biotechnology devoted to honor Herman J. Phaff. On behalf of his former students, Sally Meyer, in a personally touched talk showed him as the teacher, scientist, colleague, friend and the man. Not only Phaff's students and followers represent his living legacy but also the large number of yeast strains maintained in the culture collection of the University of California, Davis, as presented by Kyria Boundy-Mills. Out of Phaff's several former students and colleagues present, Alessandro Martini, Jack Fell, Marc-André Lachance, Allen Hagler and Eric Johnson dedicated their papers to celebrate Herman Phaff. In the parallel Symposium 4 on Cell structure and morphogenesis Lodewyk Kock showed amazing pictures made by immunofluorescence, electron and confocal laser scanning microscopy on the development and liberation of ascospores. Similar sophisticated techniques were used to elucidate the mechanism of cell aggregation and Pieter van Wyk presented minute details of this process. Byron Johnson provided evidence against the contractile role of actomyosin in the septation of fission yeast. Adriana Leão-Helder described the degradation of peroxisomes in H. polymorpha, using less widely known terms such as macroexophagy and microautophagy. Eliana Barreto Bergter demonstrated that cerebrosides may be good candidates for the action of antifungal agents. Large numbers of posters were presented in both the Fermentation and the Ecologysessions 3 and 4. Of the 21 posters on fermentation, mention should be made of the elegant study by Japanese researchers (unfortunately, there were only a few participants from Japan). Yoshihiro Nakao et al. determined the whole genome sequence of a lager brewing strain and compared it to that of S. cerevisiae, supporting the view that brewing yeasts are natural hybrids between S. cerevisiae and another Saccharomyces species. Another poster from Japan by Fumihiko Omura described an improved beer fermentation by an engineered strain with enhanced proline assimilation. Judit Tornai-Lehoczki using intraspecies molecular typing methods showed the differences in yeast microbiota from different vineyards and wine-cellars. Researchers from Italy, Slovenia, Croatia and Argentina also dealt with wine fermentation, whereas four posters from Brazil and Mexico were on traditional fermented beverages. Notable was the poster by a group of Portuguese workers, Angela Xufre et al., on the use of FISH for the analysis of population dynamics in wine fermentation. From the nutritional point of view it is a warning that a number of yeasts are able to produce biogenic amines in a wide range of foods (Sandra Torriani et al.). On the other hand, Martin Bati et al. showed that yeast biomass enriched with selenium may be used as a supplement in functional foods. D. hansenii has been implicated in various fermentations but only a single poster (by Mogens Jakobsen) demonstrated its role in cheese production. Thirteen posters were shown in the Ecology session. Here again, four posters dealt with the biodiversity of yeasts in wine, five posters were on the yeast microbiota and community structure of various natural environments and plants. Johan Schnürer and Judit Kucsera demonstrated yeast antagonism to Penicillium and Cryptococcus, respectively. Gerd Gellisen (MedArtis Pharmaceuticals, Aachen, Germany) (Plenary lecture 5) in collaboration with Russian researchers described a part of an international project on Functional genomics focusing on genes involved in protein secretion and cell wall integrity. The completed sequence of H. polymorpha served as the basis of this work and the method of random integration of linear DNA fragments was used to test some 20,000 transformants. In the oral presentations of Session 3 on Yeast diversity and new methodological approaches Wouter Middelhoven showed that certain non-conventional substrates can be valuable tools for identification of basidiomycetous yeasts in the genera Trichosporon and Cryptococcus. Elena Naumova, on the other hand, emphasized the importance of genetic and molecular methods in classification and identification of ascomycetous yeasts. Interactions between yeasts and filamentous fungi were the subject of two presentations. Carlos Rosa showed that Saccharomycopsis javanensis, a predacious yeast, can be a potential agent of biological control of fruit-decaying Penicillium species. Mathias Sipiczki applied conventional identification as well as molecular methods to study co-colonization on grapes of yeasts and Botrytis; some strains of Metschnikowia pulcherrima and A. pullulans inhibited the growth of Botrytis. Mexican and French groups showed that polyamines produced by D. hansenii may be used as probiotics in fish larviculture. Wafa Masoud applied a culture-independent DGGE method to describe the yeast community during processing of coffee beans. Yeast metabolism and regulatory processes was the topic of oral presentation Session 4. In a nicely illustrated paper Paula Ludovico demonstrated the presence of apoptosis in S. cerevisiae and its applicability as a model system to study programmed cell death in higher organisms. In terms of gene expression, a process in opposite direction may be the revival of active dry yeast. Albert Mas showed results of a DNA-microarray approach to study this process. Metabolic regulation was the subject under hyperbaric stress (Isabel Belo), oxygen and glucose limitation (Elisabeth Fredlund) and fructose limitation (Christophe Roca), respectively. Elena Orlova reported on new immunostimulators. The third day of the Congress started with Plenary lecture 6 by Johan Thevelein (Catholic University, Leuven, Belgium) who spoke about the Sensing and signaling mechanisms for environmental responses in yeasts. Besides the best characterized mating factor system, in recent years several new sensing mechanisms have been discovered. The majority of these are located in the plasma membrane, but the more complex signalling factors extend into the cell interior. Yeast cells are equipped with a battery of sensing mechanisms to respond to a variety of environmental factors, nutrients, stresses, other cells and more. Two parallel symposia followed the plenary lecture. In Symposium 5 on Yeasts in food and beverages, Tibor Deák gave an overview on food spoilage yeasts from ecological and biodiversity point of view and updated the subject in the light of recent developments in genomics, also referring to the application of molecular methods. Amparo Querol presented examples of the current molecular techniques in use for the rapid detection and identification of spoilage yeasts, and Bennie Viljoen described a case study of yeasts as spoilage organisms in dairy products. In the wine field, Patricia Romano evaluated the molecular analysis of Hanseniaspora strains, whereas Doris Rauhut discussed the interaction of S. cerevisiae and Oenococcus oeni in malolactic fermentation. Javier Arrizon examined Saccharomyces and non-Saccharomyces yeasts contributing to Mexican tequila and other agave beverages. In Symposium 6 on Yeast interactions with the environment, Graeme Walker reviewed the physiological roles of metal ions in yeasts and the various strategies adapted by yeast cells to respond and to control their influence. Beneficial and harmful roles of various metals have implications in fermentation industry, environmental bioremediation and human medical and nutritional aspects. Lucia de Figueroa demonstrated that indigenous yeasts in soil and water develop resistance to heavy metals and possess a potential to accumulate and remove Cr and Cu ions from polluted sites. Four papers discussed yeast responses to environmental stress factors, such as ethanol (Grant Stanley), hyper- and hypo-osmotics (Bernard Prior), reactive oxygen species (Peter Raspor), and pressure (George Lindsey). The molecular basis of tolerance, resistance and responses to cellular stresses have been only partially identified and understood. After lunch break posters were exhibited and discussed in sessions 5 and 6 on Biotechnology and Pathogens. 23 Posters were displayed in the biotechnology session, covering fuel ethanol production, use of non-conventional and recombinant yeasts, metabolism and regulation, production of novelty substances and exploitation of natural biodiversity. P. Carvalho et al. demonstrated the use of enrichment and selective plating for isolation of species, and A.S. Cabral et al. showed a wider screening program to get isolates of mycocinogenic activity from soils and fruits. In Session 6 on Pathogens the majority of posters were focussed on cryptococci, but Candida albicans and other candidas continue to play a significant role in human pathogenesis. Rapid identification of clinical yeasts based on multiplex PCR of histone genes and a new method using hybridization with fluorescent beads bearing species-specific capture probes will contribute to the diagnosis and better understanding of epidemiology of yeast infections. The afternoon Plenary lecture 7 was presented by Graham Fleet (University of New South Wales, Sydney, Australia) who gave an overview of New developments in the ecology of yeasts in foods and beverages, and emphasized also the significant gaps in our knowledge to understand the basic physiological and biochemical processes that impact on product quality, acceptability and safety. This plenary lecture was followed by two oral presentation sessions. Session 5 on Yeast biotechnology and biosafety was mostly concerned with recombinant expression systems in various yeasts. Ricardo Otero began with an examination of recombinant S. cerevisiae expressing α-amylase from Lipomyces kononenkoae for growth on starch as sole carbon source. It was also shown that flocculent strains degraded starch more efficiently than non-flocculent strains. Ana Clara Schenberg showed another example of recombinant S. cerevisiae in which a nuclease gene from Serratia marcescens was introduced in order to reduce the nucleic acid content of cells produced for single-cell protein biomass. H. polymorpha represents a different yeast host exploited extensively for the expression of heterologous proteins, as exemplified by J. Yokosawa who constructed a recombinant strain expressing hepatitis E viral proteins. Sandra Majer obtained constructs of P. pastoris overexpressing human growth hormone, whereas Gotthard Kunze described a wide-range yeast integrative expression vector system for Arxula adeninivorans that can be used for transforming other yeast species, e.g., H. polymorpha and S. cerevisiae. The only paper in this session not dealing with recombinant yeasts was that by Stephanus Kilian who described a novel prebiotic substance, neokestose, identified from Xanthophyllomyces dendrorhous growing on sucrose as carbon source. Pathogenicity and pharmaceuticals was the subject of oral presentations in Session 6. This session, too, was strongly inspired with molecular genetics. Patrick van Dijck presented results of expression analysis of hyphal-specific genes playing a role in adhesion, invasion and virulence of C. albicans. Mara Diáz presented the application of a high-throughput bead method for rapid detection and identification of pathogenic yeasts A. Almeida reported on the development of molecular genetic tools to study Paracoccoides brasiliensis, an endemic causative agent of systemic mycosis in South America. The same species was used by a German group, represented by Rolf Weiss, to develop a novel microfermentation system using 96-well plates for high-throughput protein expression studies and efficient screening of protein variants. Nadareh Mirrashed exposed S. cerevisiae to berberine, a new natural antifungal agent, and investigated the gene expression levels in microarray experiments. The final half day of ICY-2004 begun with Plenary lecture 8 in which Bärbel Hahn-Hägerdal (Lund University, Sweden) posed again one of the main topics of the congress: Exploiting yeasts as biocatalysts for the production of chemicals, pharmaceuticals, food and feed. She surveyed the possibilities to convert hydrolysed lignocellulosic raw materials to value-added products and emphasized the advances provided by DNA technology and genetic engineering for the development of yeasts with novel capabilities. Along this line followed the presentations in Symposium 7 on Advances in yeast biotechnology. Isak Pretorius not only described numerous examples of genetically improved yeasts with enhanced wine sensory attributes, but also emphasized the need for wine industry to overcome regulatory and social obstacles blocking the way for commercial application of recombinant wine yeasts under rigorous control and surveillance. The next four speakers provided specific examples for the use of yeasts in various biotechnological production processes. Mike Ingledew discussed the advances of improved process flow to produce fuel ethanol from feed-grade corn mash, and H.V. Amorim showed that electrophoretic karyotyping was an effective method to distinguish non-Saccharomyces yeasts and select wild Saccharomyces strains, better adapted to industrial ethanol fermentation. Badal Saha discussed problems and prospects in developing a cost-effective process for production of xylitol from agricultural residues with yeasts such as Candida peltata. Vladimir Jirku described that yeasts attached to carriers were more resistant than free suspended cells to pollutants and acted as efficient biodegraders in water remediation. The efficacy of this process could be enhanced by the addition of humic acid. Jian Zhuge demonstrated that 30–50% decrease in diacetyl production could be attained by either decreased or enhanced expression of genes responsible for production or decomposition of this off-flavor compound, respectively. The last session, Symposium 8 was completely devoted to Cryptococcus ecology and pathogenicity. Wieland Meyer warned that a new molecular type, VGII of Cr. gattii, originally found on eucalyptus trees in Australia, may be an emerging pathogenic form isolated recently in several clinical and environmental sources from various regions of the Globe. Teun Boekhout presented results from a multilocus sequence analysis showing the occurrence of intraspecific subgroups of Cr. neoformans, and indicated that a nematode, Caenorhabditis elegans can be used as model organism to study virulence factors and pathogenicity. Marcia Lazéra showed that both Cr. neoformans and Cr. gattii are associated with decaying trees in Brazil. A.L.T. Dias analyzed the susceptibility of Cr. neoformans strains to azole derivatives and pointed out that natural resistance may occur among environmental isolates. Marilene Vainstein added new information about the natural sources of Cryptococcus vars. gattii and grubii, and about their genetic and serological types in Brazil. From the papers presented in this final session, it has become evident that Cr. neoformans varieties continue to be significant threats and further research is necessary to reveal more details on the ecology and epidemiology of these important pathogenic yeasts. In conclusion, the 11th ICY provided an outstanding forum for yeast workers gathered from all over the World to survey the present status, problems and prospects of yeast research. The more than 200 participants from 34 countries presented 90 plenary lectures and oral presentations and showed more than one hundred posters. Though the presentations were distributed in several main sessions on metabolism, regulation, biotechnology, taxonomy, evolution, ecology, biodiversity and others, all these lines have been interwoven and pervaded by molecular techniques, their use and applications amply reflecting the era of molecular biology and progress which yeast researchers must keep pace with. The friendly and social atmosphere during, between and after sessions allowed participants to regain former relations and make new acquaintances, moreover to discuss further collaborations in various projects. The organizers, in the first place Leda Mendonça-Hagler and her team, deserve all appreciation and thanks for their devotion to set the stage for a memorable Congress. At the closing ceremony, both the resigning president, Lex Scheffers, and the incoming president, Leda Mendonça-Hagler, of the International Commission on Yeasts, received an enthusiastic applause for their accomplishments. © 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
TI - The 11th International Congress on Yeasts (ICY 2004), Rio de Janeiro, Brazil, 15–20 August 2004
JF - FEMS Yeast Research
DO - 10.1016/j.femsyr.2004.12.002
DA - 2005-02-01
UR - https://www.deepdyve.com/lp/oxford-university-press/the-11th-international-congress-on-yeasts-icy-2004-rio-de-janeiro-bD4HcUmY20
SP - 485
EP - 489
VL - 5
IS - 4
DP - DeepDyve
ER -