Biology and biotechnology of Trichoderma

Fungi of the genus Trichoderma are soilborne, green-spored ascomycetes that can be found all over the world. They have been studied with respect to various characteristics and applications and are known as successful colonizers of their habitats, efficiently fighting their competitors. Once established, they launch their potent degradative machinery for decomposition of the often heterogeneous substrate at hand. Therefore, distribution and phylogeny, defense mechanisms, beneficial as well as deleterious interaction with hosts, enzyme production and secretion, sexual development, and response to environmental conditions such as nutrients and light have been studied in great detail with many species of this genus, thus rendering Trichoderma one of the best studied fungi with the genome of three species currently available. Efficient biocontrol strains of the genus are being developed as promising biological fungicides, and their weaponry for this function also includes secondary metabolites with potential applications as novel antibiotics. The cellulases produced by Trichoderma reesei, the biotechnological workhorse of the genus, are important industrial products, especially with respect to production of second generation biofuels from cellulosic waste. Genetic engineering not only led to significant improvements in industrial processes but also to intriguing insights into the biology of these fungi and is now complemented by the availability of a sexual cycle in T. reesei/Hypocrea jecorina, which significantly facilitates both industrial and basic research. This review aims to give a broad overview on the qualities and versatility of the best studied Trichoderma species and to highlight intriguing findings as well as promising applications

Light regulation of metabolic pathways in fungi

Light represents a major carrier of information in nature. The molecular machineries translating its electromagnetic energy (photons) into the chemical language of cells transmit vital signals for adjustment of virtually every living organism to its habitat. Fungi react to illumination in various ways, and we found that they initiate considerable adaptations in their metabolic pathways upon growth in light or after perception of a light pulse. Alterations in response to light have predominantly been observed in carotenoid metabolism, polysaccharide and carbohydrate metabolism, fatty acid metabolism, nucleotide and nucleoside metabolism, and in regulation of production of secondary metabolites. Transcription of genes is initiated within minutes, abundance and activity of metabolic enzymes are adjusted, and subsequently, levels of metabolites are altered to cope with the harmful effects of light or to prepare for reproduction, which is dependent on light in many cases. This review aims to give an overview on metabolic pathways impacted by light and to illustrate the physiological significance of light for fungi. We provide a basis for assessment whether a given metabolic pathway might be subject to regulation by light and how these properties can be exploited for improvement of biotechnological processes

Molecular ecological aspects of Trichoderma that should be considered prior its application in agriculture and industry

Zusammenfassung in deutscher SpracheThe mycoparasitic filamentous fungus Trichoderma is frequently listed among the most economically significant microorganisms because of its key role in the production of industrial enzymes such as cellulases and hemicellulases that besides other roles are proposed for the second generation biofuel production. Even more importantly Trichoderma is intensively used in agriculture as an agent of biological control of plant pathogenic fungi (biocontrol) and as biofertilizer. On the contrary there are also known adverse effects of the mycoparasitic activity of Trichoderma as some species of the genus are pathogenic to the commercial mushrooms. Furthermore, at least two species of the genus are important to mankind as opportunistic pathogens of immunocompromised humans. The focus of this thesis is put on the possible negative effects of the genus Trichoderma such as (i) the investigation of causative agent(s) of the mushroom green mold disease; (ii) production of putatively toxic secondary metabolites and (iii) ability to cause invasive mycoses in humans. Some properties, like mycoparasitism, are characteristic of a wide variety of species in the genus. Other properties, like opportunistic attacks on mammals with immunodeficiency or green mold disease, seem to be restricted to certain taxa. Thus, the great diversity of applications combined with ecological adaptability of the genus Trichoderma makes for a deeper understanding of its ecology and diversity the worthwhile.Dem filamentösen und mykoparasitären Pilz Trichoderma kommt eine Schlüsselrolle in der industriellen Produktion von Enzymen zu und wird unter Anderem verwendet, um Cellulasen und Hemicellulasen zu produzieren. Trichoderma wird dabei häufig im gleichen Atemzug mit anderen wirtschaftlich relevanten Mikroorganismen erwähnt. Durch seine Rolle als Enzymproduzent wird Trichoderma bei der zur Produktion von Biotreibstoffen der zweiten Generation eine bedeutende Rolle zugeschrieben. Darüber hinaus findet der Pilz Anwendung in der Landwirtschaft, wo er als Mittel zur biologischen Kontrolle von pflanzenpathogenen Pilzen (Biocontrol) eingesetzt wird als auch als Biodünger Verwendung findet. In der Gattung Trichoderma finden sich aber auch Vertreter, die als mykoparasitäre Pathogene von kommerziell genutzter Pilze bekannt sind. Auch im Humanbereich spielen zwei Arten dieses Genus als opportunistische Krankheitserreger, vor allem bei immungeschwächten Menschen, eine Rolle. Der Fokus dieser Arbeit ist auf mögliche negative Auswirkungen durch Vertreter der Gattung Trichoderma gerichtet. Die Arbeit untersucht (i) den Zusammenhang zwischen den ursächlichen Substanzen die die grüne Schimmel-Krankheit bei Pilzen verusachen, (ii) ob Trichoderma potentiell toxische Sekundärmetaboliten bildet und (iii) wie Trichoderma invasive Mykosen bei Menschen hervorruft. Manche negativen Eigenschaften, wie Mykoparasitismus, sind charakteristisch für eine Vielzahl von Trichoderma Specien. Andere, wie die opportunistische Pathogenität für immungeschwächte Säugetiere oder die grüne Schimmelpilz-Krankheit, sind widerum auf wenige Taxa beschränkt. Die Vielzahl an Einsatzmöglichkeiten sowie die ökologische Anpassungsfähigkeit von Trichoderma machen diesen Pilz ein lohnenswertes Forschungsobjekt, um tieferes Verständnis für seine Ökologie und Vielfältigkeit zu entwickeln.15

Fungal genus Hypocrea/Trichoderma: from barcodes to biodiversity* §

Hypocrea/Trichoderma is a genus of soil-borne or wood-decaying fungi containing members important to mankind as producers of industrial enzymes and biocontrol agents against plant pathogens, but also as opportunistic pathogens of immunocompromised humans and animals, while others can cause damage to cultivated mushroom. With the recent advent of a reliable, BarCode-aided identification system for all known taxa of Trichoderma and Hypocrea, it became now possible to study some of the biological fundamentals of the diversity in this fungal genus in more detail. In this article, we will therefore review recent progress in (1) the understanding of the geographic distribution of individual taxa; (2) mechanisms of speciation leading to development of mushroom diseases and facultative human mycoses; and (3) the possible correlation of specific traits of secondary metabolism and molecular phylogeny