Class Agonomycetales lacking spores Industriallly relevant imperfect fungi 1. Tolypocladium inflatum : source of the immunosupressant ciclosporin 2. Penicillium notatum and P. chrysogenum : produce antibiotics 3. Penicillium roqueforti : blue cheese production and food flavoring 4. Penicillium camemberti :production of Camembert and Brie cheeses 32
5. Penicillium roqueforti is used to improve both the taste and the texture of cheeses (blue cheese) 6. Aspergillus oryzae : used in brewery, Japanese sake, miso and soy souce 7. Aspergillus niger : produce mycotoxins and pathogenic to plants. Used in citric acid, gluconic acid and enzyme production 8. Veticillium sp . and Meria sp : these produce conidia which can kill Nematodes (biopesticides) 33
2. Zygomycota The name comes from zygosporangia, where resistant spherical spores are formed during sexual reproduction. Approximately 1060 species are known. They are mostly terrestrial in habitat, living in soil or on decaying plant or animal material. Some are parasites of plants, insects, and small animals, while others form symbiotic relationships with plants. Zygomycete hyphae may be coenocytic, forming septa only where gametes are formed or to wall off dead hyphae. The common example of a zygomycete is black bread mold ( Rhizopus stolonifer ), a member of the Mucorales. It spreads over the surface of bread and other food sources, sending hyphae inward to absorb nutrients. In its asexual phase it develops bulbous black sporangia at the tips of upright hyphae, each containing hundreds of haploid spores. 34
As in most zygomycetes, asexual reproduction is the most common form of reproduction. Sexual reproduction in Rhizopus stolonifera , as in other zygomycetes, occurs when haploid hyphae of different mating types are in close proximity to each other. Growth of the gametangia commences after gametangia come in contact. Fusion of the cytoplasm, occurs followed by the fusion of the nuclei to produce a diplod zygosporangia. Zygosporangia are typically thick-walled, highly resilient to environmental hardships, and metabolically inert. They germinate to produce a sporangium or vegetative hyphae when conditions improve. Meiosis occurs during germination of the zygosporagium so the resulting spores or hyphae are haploid. LIFE CYCLE OF BLACK BREAD MOLD 35
3. ASCOMYCOTA The Ascomycota, or sac fungi, accounts for approximately 75% of all described fungi. It includes most of the fungi that combine with algae to form lichens, and the majority of fungi that lack morphological evidence of sexual reproduction. Among the Ascomycota are some famous fungi: Saccharomyces cerevisiae , the yeast used in baking and brewing industry Penicillium chrysogenum , producer of penicillin, Morchella esculentum , the edible morel, and Neurospora crassa , the "one-gene-one-enzyme" organism.
You've reached the end of your free preview.
Want to read all 72 pages?