【文章內容簡介】 ise to a new cell. Colony formation● Colony: visible aggregate of bacterial growth on a solid culture medium. It is a important characteriastics for identifying a certain bacterial species.● Colonyforming unit: aggregate of cells gives rise to a single colony in the plate—count technique. Abbreviation:cfu Actinomycetes The characteristics of Actinomyctes● G+ bacteria● Filamentous substrate myceliumhyphae→mycelium aerial mycelium conidiospores forming spores sporangiospores● Reproduction ● Fragmentation ● Formation of spores● colony ● Size small, round shape, tight, dry, diverse color, smell soil.● nutrient and environmental factors required for growth ● chemoorganotroph ● aerobe ● neutral pH ● optimal growth temperature: 23~37℃50~65℃● They are distributed mainly in soils. They can grow in soils which have less water content than that needed for most other bacteria, because of their spores that can survive well in dry soil.● denifination:Actinomycetes: Gram positive bacteria that are characterized by the formation of branching filaments and spores. The roles of Actinomycetes in nature● Many actinomycetes, such as, streptomycetes, can degrade polymeric organic substances in soil that are refractory to being deposed by many other microorganism, ., starch, pectin, chitin● produce antibiotics, antifungal antibiotics● Fix N2: Frankia, These group of bacteria are highly efficient microaerophilic N2—fixers that occur within the root nodules of plants. Unlike Rhizobium spcies, however, they infect nonleguminous woody plants, such as alders.● some species are pathogenic to plants and humans. Cyanobacteria● prokaryotic oxygenic photolithotrophs containing chlorophyll a and phycobilins● Algae: phototrophic eukaryotic microorganisms ArchaeaAn evolutionarily distinct domain of prokaryotes consisting of the methanogens, most extreme halophiles and hyperthermorphiles, and Thermoplasma.2. Eucaryotic Microorganisms Features distinguishing Eucaryotic fro prokaryotic cells, see Fungi—Molds and yeasts Characteristics of fingi Morphology Yeastyeast cells are larger than most bacteria. Yeasts vary considerably in size, ranging from 1~5 μm in width and from 5~30μm or more in length. They are monly egg—shaped, but some are spherical. Each species has a characteristic shape, but even in pure culture there is considerable variation in size and shape of individual cells, depending on age and environment. MoldThe thallus of a mold consists essentially of two parts: the mycelium (mycelia) and the spores ( resistant, dormant cells)● The mycelium The mycelium is a plex of several filaments called hyphae (singular, hypha), New hyphae generally arise from a spore germination. Each hypha is about 5~10μm wide. There are three types of hyphae: Yeasts~bacteria Colony molds~Actinomycetes Reproduction Asexual Reproduction Fungi reproduce naturally by a varity of means. Asexual reproduction (also called somatic or vegetative reproduction) does not involve the union of nuclei, sex cells, or sex organs.● Budding of somatic cells or spores● Fragmentation of the hyphal cells, each fragment being a new cell● Formation of asexual spores. Asexual spores are produced in large numbers. There are many kinds of asexual spores: Sexual reproduction sexual reproduction is carried out by fusion of the patible nuclei of two parent cells. The process of sexual reproduction begins with the joining of two cells and fusion of their protoplasts (plasmogamy), thus enabling the two haploid nuclei of two mating types to fuse together (karyogamy) to form a diploid nucleus. This followed by meiosis, which again reduces the number of chromosomes to the haploid number. Sexual spores are produced by the fusion of two nuclei. There are several types of sexual spores： Classification of FungiAinsworth classification system MyxomycotaMycetalia Mastigomycotina: nonseptate mycelium, sporangiospores, flagella, oospores Zygomycotina: nonseptate mycelium, sporangiospores, no flagella, zygosporesEumycota Basidiomycotina: septata mycelium, BasidiosporesAsycotina: septate mycelium, AscosporesDeuteromycotina: septate mycelium, conidiospores, sexual reproduction has not been found Physiology and ecology● Fungi are chemoorganotrophic organisms that have no chlorophyll. They require organic pounds for energe source and nutrition.● The saprophytes Some fungi feed on dead organic matter, they are known as saprophytes. Saprophytes depose plex Plant and animal remains, breaking them down into simpler chemical substances that are returned to the soil, thereby increasing soil fertility. These simpler chemical substances can be used by other organisms to produce useful products. This is very important to reduce organic waste in environment.● The parasites Some fungi are living in or on another organism. They are called cause diseases in plants, humans and other animals. Although fungal diseases are less monly encountered than bacterial or virus diseases in humans and other animals, they are of great importance in causing diseases of plants.● Fungi are better able to withstand extreme environmental conditions than most other microorganisms. For example, yeasts and molds can grow in a substrate or medium containing high concentrations of sugars that inhibit most bacteria。 this is why jams may be spoiled by molds but not by bacteria. Yeast and mold generally can tolerate more acidic conditions than other microbes.● Some yeasts are facultative。 that is they can grow under both aerobic and anaerobic conditions. Molds are aerobic microorganisms.● Fungi grow over a wide range of temperature the optim