Bacteria (taxonomy) Chapter 11, pp 267-298 (especially see
Table 11-2, pp272-273)
The principle bacterial groups according to the basic
organization of Bergey’s Manual.
A) Spirochetes: Fig 11-27, p289
-generally gram neg.
-mobility via axial filament
-helical or corkscrew in shape
-saprophytes to obligate parasites, found in many environments
including mouth
Treponema pallidum - causes syphilis, usually observed
with fluorescence or
dark field microscopy
Borrelia burgdorferi - causes Lyme disease
B) Aerobic, Motile, Helical/Vibrioid Gram Negative Bacteria
Campylobacter fetus - abortion in domestic animals
Campylobacter jejuni - foodborne intestinal disease
C) Gram negative aerobic rods and cocci:
-energy via aerobic oxidation of organic compounds
Pseudomonas - resistant to many disinfectants and
antibiotics; may cause opportunistic
infections in hospitals; some species have pigments (Fig 11-13,
p281); some able to degrade complex
organic compounds; common agent to spoil milk at 4°C
Legionella pneumophila - legionaires disease; found in
cooling towers of air conditioning
units
Neisseria gonorrhoeae - pencillin sensitive (usually)
diplococcus; guess what it causes.
Again this is a gram neg. category
Neisseria meningitidis - meningococcal meningitis
Bordetella pertussis - causes whooping cough
Rhizobium - fix N2 when associated with roots of legumes
(clover, alfalfa, etc.) in a
mutualistic relationship with the legume. This converts the
nitrogen into forms usable
by plants. (Fig 11-21, p285)
Agrobacterium tumefaciens - causes crown gall in plants
(tumor like condition) as a
result of the bacterial plasmid being inserted into the plant
genome. Possibly a vehicle
for genetic engineering in plants (fig 11-20, p285)
D) Facultatively anaerobic gram negative rods:
- major representatives here are the enterobacteria or enterics
(coliforms); many are
common intestinal bacteria, some are pathogens, pili are common
Enterobacteriaceae (Enterics): (Fig 11-15, p282)
Escherichia - common intestinal bacteria, most highly
studied bacteria, presence in
water or food indicates fecal contamination, causes some urinary
tract infections,
travelers diarrhea
Salmonella - generally pathogenic causing foodborne
illnesses (salmonellosis) and typhoid fever (S. typhi ), genus
divided into over 2000 serotypes
Shigella -bacillary dysentery or shigellosis
Klebsiella pneumoniae - causes septicemia and pneumonia
Proteus - urinary tract infections
Yersinia pestis - causes bubonic plague (black death),
carried by rodents, transmitted
by fleas
Enterobacter aerogenes - urinary tract infections
Vibrionaceae:
Vibrio cholerae - comma or curved shape that causes
cholera
V. parahaemolyticus - less severe gastroenteritis
Pasteurellaceae:
Hemophilus influenzae - a common cause of meningitis in
young children, a vaccine is
available. Does not cause the “flu”
Gardnerella vaginalis - common causative agent of
vaginitis
E) Anaerobic, Gram Negative, Straight, Curved, and Helical Rods
Bacteroides - common inhabitants of large intestine, infections
usually from puncture
wounds or surgery
F) Rickettsias and Chlamydias:
-gram negative, most are obligate intracellular parasites,
smaller than most bacteria
Rickettsias - generally transmitted to humans by insects and
ticks, diseases they cause
include epidemic typhus (R. prowazekii ), endemic murine typhus
(R. typhi ) and rocky mountain spotted fever (R. rickettsii )
Chlamydia - unable to make ATP on their own
Chlamydia trachomatis - causes blindness; represents
most common sexually
transmitted disease in the US, can cause lymphogranuloma venereum
G) Mycoplasmas:
- lack cell walls, have sterols in membrane to stabilize
membrane; very small
(0.1-0.25µm) and may pass thru membrane filters
Mycoplasma pneumoniae - causes “walking
pneumonia”
Ureaplasma - hydrolyze urea, cause urinary tract
infections
H) gram positive cocci:
Staphylococcus - grapelike clusters, pathogenic species
present
Staphylococcus aureus - yellow pigmented colonies;
common on skin, nasal passageways;
resists drying and high salt; causes skin problems, food
poisoning, toxic shock
syndrome
Streptococcus - grow in chains; many times initial
classification depends on type of
hemolysis evident on blood agar plates (alpha, beta, etc.) (Fig
11-3, p275 for appearence of cells)
Streptococcus pyogenes - causes pharyngitis, scarlet
fever
Streptococcus pneumoniae - pneumonia (cells usually in
pairs)
Streptococcus mutans - tooth decay
Micrococcus luteus - also common on skin, has yellow
appearing colonies
I) Endospore forming gram positive rods and cocci: (Fig 11-16,
p283)
Bacillus - some produce antibiotics; Bacillus anthracis
causes anthrax.
Bacillus thuringiensis - insect pathogen
Clostridium - obligate anaerobes; various species cause
tetanus, botulism, gangrene.
C. tetani, C. botulinum, C. perfringens
J) Regular nonsporing gram positive rods:
Lactobacillus -produce lactic acid from carbohydrates,
common in vagina, intestines,
and oral cavity; used in food industry (yogurt, sauerkraut, etc)
Listeria monocytogenes = food poisoning
K) Irregular nonsporing gram positive rods (pleomorphic):
Corynebacterium diphtheriae - diphtheria
Propionibacterium acnes - common on skin, implicated in
acne
Actinomyces israelii - form filaments, causes
actinomycosis
L) Mycobacterium:
- acid fast due to high lipid content, essentially stain gram
(+); causes tuberculosis,
leprosy (M. tuberculosis and M. leprae)
M) Gliding fruiting bacteria:
- glide on a slime layer; able to aggregate forming stalked
fruiting bodies
Myxobacteria - used to study genes involved in this
social behavior
N) Archaeobacteria (Archaea):
- generally found in harsh environments, cell walls lack typical
peptidoglycan
layer, membrane lipids = ether linked
Halobacterium and Halococcus - require high
salt concentrations 2-2.5M (Dead Sea)
has protein cell wall - only stable in high salt
Sulfolobus and Thermoplasma - thermoacidophiles
requiring acid conditions and high
temperatures (pH 2, 60°C)
Methanobacterium - and other methanogens produce methane
from a variety of sources;
could be used as an energy source
O) Cyanobacteria: (Fig 11-7, p278)
- oxygenic phototrophic bacteria possessing thylakoid membranes
(but not enclosed in
chloroplasts like they are in plants); some grow in chains and
may have specialized cells
able to carry out nitrogen fixation and these specialized cells
are referred to as
heterocysts, found in soil and aquatic environments
P) Actinomycetes: (morphology resembles filamentous fungi, common
in soil)
Streptomyces - common soil bacteria; produce branching
hyphae (mycelia); reproduce
by asexual spores; produce many different antibiotics (such as
streptomycin)
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