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1、Chaper 1,Introduction,Chapter 3 Bacteria,Size, Shape, and Arrangement of Bacterial Cells,Most bacteria fall within a range from 0.2 to 2.0 m in diameter and from 2 to 8m in length. They have a few basic shapes-spherical coccus (plural, cocci, meaning berries), rod-shaped bacillus (plural, bacilli, m
2、eaning little staffs), and spiral.,Cm = 10-2 meter mm = 10-3 meter m = 10-6 meter nm = 10-9 meter,Bacteria,The thousands of species of bacteria are differentiated by many factors, including morphology (shape), chemical composition (often detected by staining reactions), nutritional requirements, bio
3、chemical activities, and source of energy (sunlight or chemicals).,How to identify an unknown bacterial species ?,Arrangement of Spherical Bacterial Cells,diplococci,streptococci,tetracocci,sarcinae,staphylococci,Sphericalcoccus,The Micrococcaceae,The family Micrococcaceae contains gram-positive coc
4、ci, 0.5-2.5 m in diameter, that divide in more than one plane to form regular or irregular clusters of cells. All are aerobic or facultatively anaerobic. The peptidoglycan di-amino acid is L-lysine. The three most important genera are:,Micrococcus Staphylococcus Streptococcus,Micrococcus aerobic, gr
5、am-positive, catalase positive, cell arranges mainly in pairs, tetrads, or irregular clusters, nonmotile. They are often yellow, orange or red in colour,Staphylococcus - facultatively anaerobic, gram-positive, usually form irregular clusters, nonmotile, catalase positive but oxidase negative, fermen
6、t glucose anaerobically.,staphylococci,staphylococci,Streptococcus - facultatively anaerobic or microaerophilic, catalase negative, gram-positive, Cell arranges in pairs or chains, usually nonmotile, A few species are anaerobic rather than facultative.,Bacilli divide only across their short axis, so
7、 there are fewer groupings of bacilli than of cocci.,Rod-shaped bacteria,Diplobacilli,streptobacilli,Single bacillus,Coccobacillus,Clostridium botulinus C. butyricum C. aceticum C. tetani C. putrificum,Bacillus subtilis, B. Mycoides B. Pastturii B. megaterium B. Thuringiensis B. Anthracis B. Botulin
8、us B. cereus,Spore-forming rod shaped bacteriaAlmost all Spore-forming bacteria are Gram+,Clostridium Anaerobic,Bacillus Aerobic,Nonspore - forming rod shaped bacteria Most nonspore forming rod shaped bacteria are Gram-,Representatives: Escherchia col Prote Pseudomonas,Vibrio, Spirillum and Spiroche
9、te,Some bacteria are shaped like long rods twisted into spirals or helices; they are called vibrios (like commas or incomplete spirals), spirilla if rigid and spirochetes when flexable.,vibrio,spirillum,spirochete,0.2-0.5m in diameter. obligate intracellular parasites. The majority of them are gram-
10、negative and multiply only within host cells. Binary fission within host cells.They lack the enzymatic capability to produce sufficient amounts of ATP to support their reproduction. They obtain the ATP from host cells. Many species of them cause disease in humans and other animals.,Rickettsia,They a
11、re obligate intracellular parasites, unable to generate sufficient ATP to support their reproduction. gram-negative and cell divides by binary fission They Chlamydia cause human respiratory and genitourinary tract disease, and in birds they cause respiratory disease.,Chlamydia,Diameter=0.1-0.25 m. They lack cell wall, are bounded by a single triple-layered membrane. They are the smallest organisms capable of self-reproduction. The colony is “fried egg” appearance. Several of them cause diseases in humans. (pneumonia, respiratory tract disease),Mycoplasma,
