6 ● The nucleus ● not bounded by nuclear membrane ● one circular chromosome ● chromosome does not contain histones ● nucleolus absent ● Plasmid In addition to the normal DNA chromosome, extrachromosomal genetic elements are offen found in bacteria. These elements are called plasmids, and are capable of autonomous replication in the cytoplasm in the bacterial cell. Plasmids are circular pieces of DNA that are extra genes. 1.2.2 Bacterial Reproduction and colony 1.2.2.1 Reproduction ● Transverse Binary Fission The most common mode of bacterial cell division in the usual growth cycle of bacterial populations is transverse binary fission, in which a single cell divides into two cells after developing a transverse septum. Transverse binary fission is an asexual reproductive process. ● Budding some bacteria reproduce by budding, a process in which a small protuberance ( bud ) develops at one end of the cell. This enlarges and eventually develops into a new cell which separates from the parent. ● Fragmentation Bacteria that produce extensive filaments, such as Nocardia species, reproduce by fragmentation of the filaments into small bacillary or coccoid cells, each of which gives rise to a new cell. ● Formation of conidiospores or sporangiospores Species of the genes streptomyces and related bacteria produce many spores by developing crosswalls (septation) at the hyphal tips. Each spore gives rise to a new cell. 1.2.2.2 Colony formation ● Colony: visible aggregate of bacterial growth on a solid culture medium. It is a important characteriastics for identifying a certain bacterial species. ● Colony-forming unit: aggregate of cells gives rise to a single colony in the plate—count technique. Abbreviation:cfu 1.2.3 Actinomycetes 1.2.3.1 The characteristics of Actinomyctes ● G+ bacteria ● Filamentous substrate mycelium hyphae→mycelium aerial mycelium conidiospores forming spores sporangiospores ● Reproduction ● Fragmentation ● Formation of spores
6 ● The nucleus ● not bounded by nuclear membrane ● one circular chromosome ● chromosome does not contain histones ● nucleolus absent ● Plasmid In addition to the normal DNA chromosome, extrachromosomal genetic elements are offen found in bacteria. These elements are called plasmids, and are capable of autonomous replication in the cytoplasm in the bacterial cell. Plasmids are circular pieces of DNA that are extra genes. 1.2.2 Bacterial Reproduction and colony 1.2.2.1 Reproduction ● Transverse Binary Fission The most common mode of bacterial cell division in the usual growth cycle of bacterial populations is transverse binary fission, in which a single cell divides into two cells after developing a transverse septum. Transverse binary fission is an asexual reproductive process. ● Budding some bacteria reproduce by budding, a process in which a small protuberance ( bud ) develops at one end of the cell. This enlarges and eventually develops into a new cell which separates from the parent. ● Fragmentation Bacteria that produce extensive filaments, such as Nocardia species, reproduce by fragmentation of the filaments into small bacillary or coccoid cells, each of which gives rise to a new cell. ● Formation of conidiospores or sporangiospores Species of the genes streptomyces and related bacteria produce many spores by developing crosswalls (septation) at the hyphal tips. Each spore gives rise to a new cell. 1.2.2.2 Colony formation ● Colony: visible aggregate of bacterial growth on a solid culture medium. It is a important characteriastics for identifying a certain bacterial species. ● Colony-forming unit: aggregate of cells gives rise to a single colony in the plate—count technique. Abbreviation:cfu 1.2.3 Actinomycetes 1.2.3.1 The characteristics of Actinomyctes ● G+ bacteria ● Filamentous substrate mycelium hyphae→mycelium aerial mycelium conidiospores forming spores sporangiospores ● Reproduction ● Fragmentation ● Formation of spores
7 ● 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. 1.2.3.2 The roles of Actinomycetes in nature ● Many actinomycetes, such as, streptomycetes, can degrade polymeric organic substances in soil that are refractory to being decomposed by many other microorganism, e.g., 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. 1.2.4 Cyanobacteria ● prokaryotic oxygenic photolithotrophs containing chlorophyll a and phycobilins ● Algae: phototrophic eukaryotic microorganisms 1.3 Archaea An evolutionarily distinct domain of prokaryotes consisting of the methanogens, most extreme halophiles and hyperthermorphiles, and Thermoplasma
7 ● 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. 1.2.3.2 The roles of Actinomycetes in nature ● Many actinomycetes, such as, streptomycetes, can degrade polymeric organic substances in soil that are refractory to being decomposed by many other microorganism, e.g., 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. 1.2.4 Cyanobacteria ● prokaryotic oxygenic photolithotrophs containing chlorophyll a and phycobilins ● Algae: phototrophic eukaryotic microorganisms 1.3 Archaea An evolutionarily distinct domain of prokaryotes consisting of the methanogens, most extreme halophiles and hyperthermorphiles, and Thermoplasma
8 2. Eucaryotic Microorganisms 2.1 Features distinguishing Eucaryotic fro prokaryotic cells, see 1.1 2.2 Fungi—Molds and yeasts 2.2.1 Characteristics of fingi 2.2.1.1 Morphology 2.2.1.1.1 Yeast yeast 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 commonly 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. 2.2.1.1.2 Mold The thallus of a mold consists essentially of two parts: the mycelium (mycelia) and the spores ( resistant, dormant cells) ● The mycelium The mycelium is a complex 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 2.2.1.1.3 Colony molds~Actinomycetes 2.2.1.2 Reproduction 2.2.1.2.1 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 becoming a new cell ● Formation of asexual spores. Asexual spores are produced in large numbers. There are many kinds of asexual spores: 2.2.1.2.2 Sexual reproduction sexual reproduction is carried out by fusion of the compatible 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： 2.2.1.3 Classification of Fungi Ainsworth classification system
8 2. Eucaryotic Microorganisms 2.1 Features distinguishing Eucaryotic fro prokaryotic cells, see 1.1 2.2 Fungi—Molds and yeasts 2.2.1 Characteristics of fingi 2.2.1.1 Morphology 2.2.1.1.1 Yeast yeast 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 commonly 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. 2.2.1.1.2 Mold The thallus of a mold consists essentially of two parts: the mycelium (mycelia) and the spores ( resistant, dormant cells) ● The mycelium The mycelium is a complex 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 2.2.1.1.3 Colony molds~Actinomycetes 2.2.1.2 Reproduction 2.2.1.2.1 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 becoming a new cell ● Formation of asexual spores. Asexual spores are produced in large numbers. There are many kinds of asexual spores: 2.2.1.2.2 Sexual reproduction sexual reproduction is carried out by fusion of the compatible 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： 2.2.1.3 Classification of Fungi Ainsworth classification system
9 Myxomycota Mastigomycotina: nonseptate mycelium, sporangiospores, flagella, oospores Zygomycotina: nonseptate mycelium, sporangiospores, no flagella, zygospores Eumycota Basidiomycotina: septata mycelium, Basidiospores Ascomycotina: septate mycelium, Ascospores Deuteromycotina: septate mycelium, conidiospores, sexual reproduction has not been found 2.2.1.4 Physiology and ecology ● Fungi are chemoorganotrophic organisms that have no chlorophyll. They require organic compounds for energe source and nutrition. ● The saprophytes Some fungi feed on dead organic matter, they are known as saprophytes. Saprophytes decompose complex 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 parasites.Parasites cause diseases in plants, humans and other animals. Although fungal diseases are less commonly 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 optimal growth temperature: 22~30℃ saprophytic species 30~37℃ pathogenic species Some fungi can grow at or near 0℃ and thus can cause spoilage of meat and vegetables in cold storage. ● There are many differences between fungi and bacteria. A summary is listed in the following table. Mycetalia
9 Myxomycota Mastigomycotina: nonseptate mycelium, sporangiospores, flagella, oospores Zygomycotina: nonseptate mycelium, sporangiospores, no flagella, zygospores Eumycota Basidiomycotina: septata mycelium, Basidiospores Ascomycotina: septate mycelium, Ascospores Deuteromycotina: septate mycelium, conidiospores, sexual reproduction has not been found 2.2.1.4 Physiology and ecology ● Fungi are chemoorganotrophic organisms that have no chlorophyll. They require organic compounds for energe source and nutrition. ● The saprophytes Some fungi feed on dead organic matter, they are known as saprophytes. Saprophytes decompose complex 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 parasites.Parasites cause diseases in plants, humans and other animals. Although fungal diseases are less commonly 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 optimal growth temperature: 22~30℃ saprophytic species 30~37℃ pathogenic species Some fungi can grow at or near 0℃ and thus can cause spoilage of meat and vegetables in cold storage. ● There are many differences between fungi and bacteria. A summary is listed in the following table. Mycetalia
10 Comparative features of fungi and bacteria Characteristic Fungi Bacteria cell type optimum pH optimum temperature oxgen requirement Light requirement Sugar concentration in media Carbon requirement Cell-wall stralctural components Antibiotic susceptibility Eucaryotic 3.8~5.6 22~30℃(saprophytes) 30~37℃(parasites) strictly aerobic(molds) facultative (some yeasts) none 4~5% organic chitin, cellulose, hemicellulose resistant to penicillins, tetracyclines, chloramphenical; sensitive to griseofulvin Prokaryotic 6.5~7.5 20~37℃(mesophiles) aerobic, anaerobic facultative some photosynthetic bacteria 0.5~1% inorganic or/and organic peptidoglycan resistant to griseofulvin; sensitive to penicillins, tetracyclines, chloramphenical 2.2.1.5 Molds and their associations with other organisms ● There are some interesting partnerships in nature involving a mold and some other organism. In some of these associations the partners are dependent on each other and can not survive alone. In others, The individuals can survive independently. ● Lichens Lichens are composite organisms composed of fungi and algae, each contributing to the benefit of both. The algae synthesize carbohydrates by photosynthesis and obtain other nutrients from the fungi; the fungi depend on the algae for the organic carbon. ● Mycorrhizas Mycorrhiza is a symbiotic association of a fungus with the roots of a higher plants. This association is usually beneficial to the host plant as well as the symbiont, and sometimes the host can not thrive without the benefits derived from the fungus (e.g. orchid). Mycorrhizas enhance mineral absorption by the plants. 2.3 Algae 2.4 Protozoa 3 Viruse 3.1 The general characteristics of viruses ● noncellullar structure Virion: The structurally complete mature and infectious virus is called the virion. ● Small size Viruses are so small that they can only be seen at magnifications provided by the electron microscope. They are 10~100 times smaller than most bacteria, with an approximate size range of 20~300nm. Thus they pass through the pores of filters which do not permit the passage of most bacteria. ● Obligate intracellular parasites Viruses are incapable of independent growth in artificial media. They can grow only in animal、plant cells or microorganicms, because viruses lack metabolic. Machinery of their own to
10 Comparative features of fungi and bacteria Characteristic Fungi Bacteria cell type optimum pH optimum temperature oxgen requirement Light requirement Sugar concentration in media Carbon requirement Cell-wall stralctural components Antibiotic susceptibility Eucaryotic 3.8~5.6 22~30℃(saprophytes) 30~37℃(parasites) strictly aerobic(molds) facultative (some yeasts) none 4~5% organic chitin, cellulose, hemicellulose resistant to penicillins, tetracyclines, chloramphenical; sensitive to griseofulvin Prokaryotic 6.5~7.5 20~37℃(mesophiles) aerobic, anaerobic facultative some photosynthetic bacteria 0.5~1% inorganic or/and organic peptidoglycan resistant to griseofulvin; sensitive to penicillins, tetracyclines, chloramphenical 2.2.1.5 Molds and their associations with other organisms ● There are some interesting partnerships in nature involving a mold and some other organism. In some of these associations the partners are dependent on each other and can not survive alone. In others, The individuals can survive independently. ● Lichens Lichens are composite organisms composed of fungi and algae, each contributing to the benefit of both. The algae synthesize carbohydrates by photosynthesis and obtain other nutrients from the fungi; the fungi depend on the algae for the organic carbon. ● Mycorrhizas Mycorrhiza is a symbiotic association of a fungus with the roots of a higher plants. This association is usually beneficial to the host plant as well as the symbiont, and sometimes the host can not thrive without the benefits derived from the fungus (e.g. orchid). Mycorrhizas enhance mineral absorption by the plants. 2.3 Algae 2.4 Protozoa 3 Viruse 3.1 The general characteristics of viruses ● noncellullar structure Virion: The structurally complete mature and infectious virus is called the virion. ● Small size Viruses are so small that they can only be seen at magnifications provided by the electron microscope. They are 10~100 times smaller than most bacteria, with an approximate size range of 20~300nm. Thus they pass through the pores of filters which do not permit the passage of most bacteria. ● Obligate intracellular parasites Viruses are incapable of independent growth in artificial media. They can grow only in animal、plant cells or microorganicms, because viruses lack metabolic. Machinery of their own to