Bacterial Classification (PDF)

Figure 16.2  16.1 Alphaproteobacteria Nearly 1000 described species Many are obligate aerobes or facultative aerobes. Many are oligotrophic (grow under low nutrient concentration). Six major orders Rhizobiales, Rickettsiales, Rhodobacterales, Rhodospirillales, Caulobac...

Figure 16.2  16.1 Alphaproteobacteria Nearly 1000 described species Many are obligate aerobes or facultative aerobes. Many are oligotrophic (grow under low nutrient concentration). Six major orders Rhizobiales, Rickettsiales, Rhodobacterales, Rhodospirillales, Caulobacterales, and Sphingomonadales  Wolbachia Rickettsia Figure 16.3  Rickettsiales (Figure 16.5) key genera: Rickettsia, Wolbachia obligate intracellular parasites or mutualists (partners) of animals not yet cultured in absence of host cells; require growth in chicken eggs or host cell tissue culture typically associated with arthropods Rickettsia causative agent of several human diseases typhus Rocky Mountain spotted fever transmitted by ticks, fleas, lice, and mites  Rickettsiales Wolbachia (Figure 16.6) intracellular parasites of many insects including can induce parthenogenesis (development of unfertilized eggs), killing of males, feminization (conversion of male into female) W. pipientis best studied  Wolbachia to help control viral infection dengue virus Wolbachia are extremely common bacteria that occur naturally in 60 per cent of insect species, including some mosquitoes, fruit flies, moths, dragonflies and butterflies. Wolbachia are safe for humans and the environment. Independent risk analyses indicate that the release of Wolbachia-infected mosquitoes poses negligible risk to humans and the environment. Wolbachia live inside insect cells and are passed from one generation to the next through an insect’s eggs. Aedes aegypti mosquitoes don’t normally carry Wolbachia, however many other mosquitoes do. https://www.worldmosquitoprogram.org/en/work/wolbachia-method/how-it-works Wolbachia video https://www.youtube.com/watch?v=GKVikYJOjis A Singapore study: https://www.youtube.com/watch?v=HBE10y5kv1c https://www.youtube.com/watch?v=dQ9JLet1F8c  16.2 Betaproteobacteria 500 described species Much functional diversity Six major orders (Figure 16.7) Burkholderiales, Hydrogenophilales, Methylophilales, Neisseriales, Nitrosomonadales, and Rhodocyclales Bordetella pertussis  16.3 Gammaproteobacteria: Enterobacteriales Key genera: Enterobacter, Escherichia, Klebsiella, Proteus, Salmonella, Serratia, Shigella Largest, most diverse class of Proteobacteria (Figure 16.10) Diverse metabolic and ecological characteristics  Pseudomonas aeruginosa Legionella pneumophila Salmonella E. coli Figure 16.10  Enterobacteriales: Enteric bacteria phylogenetic group within the Gammaproteobacteria facultative aerobic, gram-negative, nonsporulating rods, sometimes motile by peritrichous flagella (Figure 16.11) Oxidase (negative) and catalase (positive) tests can be used to discriminate enteric from many other bacteria. relatively simple nutritional requirements ferment sugars to a variety of end products many pathogens and many industrially important bacteria  Fermentation patterns in enteric bacteria Enteric bacteria can be separated into two broad groups by the type and proportion of fermentation products generated by anaerobic fermentation of glucose. (Figure 16.12) Mixed-acid fermentation: acetic, lactic, and succinic acid formed in significant amounts; ethanol, CO2, and H2 also formed with CO2 and H2 in equal amounts via formate hydrogenlyase Escherichia, Salmonella, Shigella, Citrobacter, Proteus, Yersinia 2,3-butanediol fermentation: Butanediol, ethanol, CO2, H2 are main products; smaller amounts of acids formed. Enterobacter, Klebsiella, Erwinia, 2,3-butanediol Serratia  Enterobacteriales Mixed-acid fermenters: Escherichia, Salmonella, Shigella, and Proteus Salmonella and Shigella closely related to Escherichia almost always pathogenic typohid fever and gastroenteritis (Salmonella) and bacillary dysentery (Shigella) Domain: Bacteria Phylum: Proteobacteria Class: Gammaproteobacteria Salmonella Order: Enterobacterales Family: Enterobacteriaceae Genus: Salmonella Species: S. enterica  Salmonella enterica Co-discovered by Daniel Elmer Salmon, a veterinary pathologist by Veterinary Division of the United States Department of Agriculture in 1885. He earned the first D.V.M. (Doctor of Veterinary Medicine) degree awarded in the United States from Cornell University.  Salmonella enterica Many (more than 2,500) serotypes, classified by on the differences in the somatic (O) and flagellar (H) antigens. Correct naming scheme: S. enterica subsp. enterica serovar Typhi Should not be: Salmonella typhi Could be: Salmonella Typhi, S. Typhi Gram-negative, facultative anaerobic rods, non-spore- forming, motile; Fermenter; oxidase negative. Salmonella Typhi http://diversehierarchy.wikispace s.com/Eubacteria+%E2%80%93+S http://textbookofbacteriol.+enterica ogy.net/salmonella.html