Term
| Purple Nonsulfur Bacteria |
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Definition
can produce cellular cysts
resting cells
resistant to desiccation but less tolerant of heat and UV than bacterial endospores
made in response to nutrient limitation
have thick outer coat and store polyhydroxybutyrate
with one exception (genus Rhodocyclus) all are a-proteobacteria
metabolically flexible
normally grow anaerobically as anoxygenic photoorganoheterotrophs
possess bacteriochlorophylls a or b in photosystems located in membranes that are continuous with plasma membrane
some can oxidize sulfide, but not elemental sulfur, to sulfate
in absence of light
most grow aerobically as chemoorganoheterotrophs
some carry out fermentation, photoheterotrophy, photoautotrophy, and grow anaerobically
Rhodosprillum best studied metabolic diversity |
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Term
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Definition
the largest phylogenetically coherent bacterial group with more than 500 genera
remarkable diverse morphologically, physiologically, and other ways
volume 2 of Bergey’s Manual (2nd edition) is devoted to this group of bacteria |
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Term
| Class Alphaproteobacteria |
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Definition
seven orders, 20 families
Rickettsiales may have been the earliest α-proteobacteria
most of the oligotrophic bacteria
most abundant bacteria in oceans
evolved to live within plants and animals resulting in genome reduction or expansion
metabolically diverse
methylotrophy, chemolithotrophs, nitrogen fixers |
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Term
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Definition
produces H2
novel biodegradable plastic
In Alphaproteobacteria
oxidize carbon monoxide to carbon dioxide
morphologically diverse
most motile by polar flagella
found in mud and water of lakes and ponds with abundant organic matter and low sulfide levels; some marine species |
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Term
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Definition
order Rickettsiales; family Rickettsiaceae
In Alphaproteobacteria
very small, gram-negative, non-flagellated, diverse morphology
all species are parasitic or mutualistic
grows in vertebrate erythrocytes, macrophages, vascular endothelial cells
live in blood sucking arthropods – vectors or primary hosts
genome sequence similar to mitochondria
arose from endosymbiotic association
free living, aerobic bacterium became intracellular parasite of proto-eukaryotic cell that lacked organelles
gene reduction occurred and loss of free living ability
lack glycolytic pathway
do not use glucose as energy source
oxidize glutamate and TCA cycle intermediates (e.g., succinate)
take up and use ATP and other materials from host cell
reproduction
enters host by phagocytosis
escapes phagosome
reproduces in cytoplasm
host cell bursts |
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Term
| Rickettsia prowazekii and Rickettsia typhi |
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Definition
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Term
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Definition
| Rocky Mountain Spotted Fever |
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Term
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Definition
gram-negative, pleomorphic, motile rods
often contain poly-b-hydroxybutyrate
granules
grow symbiotically as nitrogen-fixing bacteroids within root nodule cells of legumes
most successful plant family on earth
In Alphaproteobacteria |
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Term
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Definition
do not stimulate nodule formation or fix nitrogen
invade crown, roots, and stems of many plants
transform infected plant cells into autonomously proliferating tumors
e.g., Agrobacterium tumefaciens
causes crown gall disease by means of tumor-inducing (Ti) plasmid
In Alphaproteobacteria |
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Term
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Definition
important human and animal pathogen
undulant fever – zoonosis
tiny, faintly staining coccobacilli
In Alphaproteobacteria |
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Term
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Definition
very diverse chemolithoautotrophs
nitrification – gain electrons from oxidation of
ammonium to nitrate or nitrite
nitrite further oxidized to nitrate
ammonia nitrite nitrate
conversion of ammonia to nitrate by action of two genera
e.g., Nitrosomonas – ammonia to nitrite
e.g., Nitrobacter – nitrite to nitrate
fate of nitrate
easily used by plants
lost from soil through leaching or denitrification
divided into several taxa
class Alphaproteobacteria
e.g., genus Nitrobacter
class Betaproteobacteria
e.g., genera Nitrosomonas and Nitrosospira
class Gammaproteobacteria
family Ectothiorhodospiraceae
e.g., genus Nitrococcus
family Chromatiaceae
e.g., genus Nitrosococcus
In Alphaproteobacteria |
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Term
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Definition
seven orders, 12 families
considerable metabolic diversity
overlap α-proteobacteria metabolically but generally use decomposed organic matter anoxically
some use hydrogen, methane, ammonia, volatile fatty acids |
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Term
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Definition
one family, Neisseriaceae and 15 genera
Genus Neisseria
In Betaproteobacteria |
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Term
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Definition
nonmotile, gram-negative cocci
most often occur in pairs with adjacent sides flattened
may have capsules and fimbriae
aerobic chemoorganotrophs
oxidase positive and usually catalase positive
may have capsules and fimbriae
inhabitants of mucous membranes of mammals
some human pathogens
Neisseria gonorrhoeae – gonorrhea
Neisseria meningitidis – meningitis
In Betaproteobacteria |
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Term
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Definition
gram-negative coccobacilli
some have capsules
aerobic chemoorganotrophs
respiratory metabolism
require organic sulfur and amino acids for growth
mammalian parasites that multiply in respiratory epithelial cells
nonmotile, encapsulated species
whooping cough and kennel cough
In Betaproteobacteria |
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Term
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Definition
number of chemolithotrophs
e.g., two genera of nitrifying bacteria
Nitrosomonas and Nitrosospira
oxidize ammonia to nitrite
enzyme ammonia monooxygenase (AMO)
enzyme hydroxylamine oxidoreductase
also auxotrophic metabolism
fixes CO2 in Calvin cycle
In Betaprotebacteria |
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Term
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Definition
found in soil and aquatic habitats
production of sulfuric acid can cause corrosion of concrete and metal structures
may increase soil fertility by releasing sulfate
used in leaching metals from low grade metal ores
In Betaproteobacteria |
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Term
| Class Gammaproteobacteria |
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Definition
largest subgroup of proteobacteria
contains 14 orders and 28 families
very diverse physiological types
chemoorganotrophs, photolithotrophs, chemolithotrophs, methylotrophs
aerobic and anaerobic
many deeply branching groups |
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Term
| The Purple Sulfur Bacteria |
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Definition
placed in order Chromatiales
divided into two families, Chromatiaceae and Ectothiorhodospiraceae
Family Ectothiorhodospiraceae contains eight genera
In Gammaproteobacteria |
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Term
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Definition
family Legionellacaea
genus Legionella
family Coxiellaceae
genera Coxiella and Rickettsiella
all are intracellular pathogens
dimorphic lifestyle (two forms)
In Gammaproteobacteria |
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Term
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Definition
L. pneumophilia intensely studied
causative agent Legionnaire’s disease
transmission through aerosols
intracellular pathogen of protozoa
invade cooling towers, air conditioning, hot tubs
gram-negative rods that replicates by binary fission
Life cycle in Protist
replicative forms (RFs) reside in host vacuole (replicative endosome)
RFs differentiate into mature intracellular forms (MIFs) which are the infectious form
MIF are metabolically dormant, heat tolerant, and resistant to antibiotics
Hsp60 is invasin used to invade host cell
In Gammaproteobacteria |
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Term
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Definition
host range
birds, insects, fish, rodents, sheep, goats, humans
transmitted through aerosol
life cycle similar to L. pneumophilia
small cell variant (SCV) enters cell by phagocytosis
phagosome low pH triggers SCV to become metabolically active
SCV differentiates into large cell variant (LCV)
replicates by binary fission, are infectious
long-term survival outside the host
In Gammaproteobacteria |
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Term
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Definition
contains family Pseudomonadaceae
Pseudomonas is the most important genus in the order Pseudomonadales
heterogenous - 60 species
gram-negative straight or slightly curved rods
0.5 to 1.0 mm by 1.5 to 5.0 mm in length
motile by one or several polar flagella
lack prosthecae or sheaths
chemoheterotrophs with respiratory metabolism
usually use oxygen as electron acceptor
sometimes use nitrate as electron acceptor
have functional TCA cycle
most hexoses are degraded by Entner-Duodoroff pathway
degrade wide variety of organic molecules
mineralization - microbial breakdown of organic materials to inorganic substrates
important experimental subjects
some are major animal and plant pathogens
some cause spoilage of refrigerated food
can grow at 4°C
In Gammaproteobacteria |
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Term
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Definition
often pleomorphic, motile rods
aerobic, catalase positive
chemoorganotrophs
widespread in soil and water
In Gammaproteobacteria |
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Term
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Definition
contains one family, Vibrionaceae; eight genera
most are aquatic, most free-living
straight or curved rods, oxidase positive, flagellated
some important pathogens
some symbiotic in luminous organs of fish
closely related to two other orders
Enterobacteriales and Pasteurellales
In Gammaproteobacteria |
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Term
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Definition
pathogen that causes cholera
genome has been sequenced
has two circular chromosomes
copies of some genes present on both chromosomes
cholera toxin gene is integrated phage on chromosome 1
In Gammaproteobacteria |
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Term
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Definition
one family, Enterobacteriaceae; 44 genera
enteric bacteria or enterobacteria
facultative anaerobes
chemoorganotrophs that degrade sugars by glycolytic pathway
can cleave pyruvate to yield formic acid (formic acid fermentation)
In Gammaproteobacteria |
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Term
| Family Enterobacteriaceae |
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Definition
two groups based on fermentation products
majority are mixed acid fermenters
produce lactate, acetate, succinate, formate, and ethanol
others are butanediol fermenters
butanediol, ethanol, and carbon dioxide
biochemical tests used to distinguish genera in addition to morphology, motility, growth responses
very common, widespread, and important
In Gammaproteobacteria |
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Term
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Definition
probably best studied bacterium
inhabitant of intestinal tracts of many animals
used as indicator organisms for testing water for fecal contamination
some strains are pathogenic
gastroenteritis
urinary tract infections
In Gammaproteobacteria |
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Term
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Definition
typhoid fever and gastroenteritis
In Gammaproteobacteria |
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Term
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Definition
bacillary dysentery
In Gammaproteobacteria |
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Term
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Definition
pneumonia
In Gammaproteobacteria |
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Term
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Definition
plague
In Gammaproteobacteria |
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Term
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Definition
blights, wilts, etc., of crop plants
In Gammaproteobacteria |
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Term
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Definition
one family, Pasteurellaceae; six genera
small, nonmotile, oxidase positive
important pathogens
Pasteurella multiocida – fowl cholera
Pasteurella haemolytica – pneumonia in cattle, sheep, and goats
Haemophilus influenzae – variety of diseases, including meningitis in children; vaccine available
In Gammaproteobacteria |
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Term
| Class Deltaproteobacteria |
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Definition
contains eight orders and 20 families
divided into two general groups
aerobic, chemoorganotrophic predators
anaerobic, chemoorganotrophic sulfur- and sulfate-reducers |
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Term
| Class Epsilonproteobacteria |
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Definition
smallest of proteobacterial classes
probably two one orders, Campylobacteriales and Nautiliales; three families
slender gram-negative rods |
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Term
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Definition
reproductive disease and abortions in cattle and sheep
Guillain-Barre syndrome triggered in molecular mimicry
septicemia and enteritis in humans
septicemia – pathogens or their toxins in blood
enteritis – inflammation of intestinal tract
In Epsilonproteobacteria |
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Term
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Definition
abortions in sheep
enteritis diarrhea in humans
In Epsilonproteobacteria |
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Term
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Definition
at least 23 species isolated from stomachs and upper intestines of mammals
e.g., Helicobacter pylori
causes gastritis and peptic ulcer disease
motility important for colonization
does not grow below pH 4.5
urease converts urea to ammonia and CO2
urea hydrolysis appears to be associated with virulence
In Epsilonproteobacteria |
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Term
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Definition
newly discovered are thermophilic, chemolithoautotrophic, and others
found in marine hydrothermal vents, terrestrial springs, ground water, oil-field brines, limestone caves, sulphidic springs
found in filamentous microbial mats in anoxic, sulfide-rich cave springs |
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