Transcript HighGCGm - University of Colorado Boulder

LECTURE 15
High GC
GRAM POSITIVE
BACTERIA
.
HIGH G+C GRAM POSITIVES
• Actinomycetes
• Corynebacteria
• Propionic acid bacteria
• Bifidobacteria
• Micrococci
ACTINOMYCETES:
morphology & reproduction
ACTINOMYCETES MORPHOLOGY
Fig. 12.15. Growth of filamentous microbes
(fungus or actinomycetes). Growth is from the
hyphal tip.
ACTINOMYCETES MORPHOLOGY
An actinomycete colony growing on agar - note the
subterranean and aerial hyphae….
ACTINOMYCETES MORPHOLOGY
IN SUMMARY:
• have filamentous growth, like fungi
• on substrate, grow on and in it
• thallus -- tissuelike mass, grown in culture
• mycelium -- tangled mass of hyphae, found in
nature
ACTINOMYCETES REPRODUCTION
ACTINOMYCETES REPRODUCTION
Fig. 11.19
Fig 11.19. Conidia of Streptomyces
ACTINOMYCETES REPRODUCTION
IN SUMMARY:
• actinomycetes (and fungi) reproduce via
spores
• hyphal growth is followed by fragmentation
and release of spores
• conidia – spores produced asexually on
aerial filaments called sporophores
• shape and arrangement of sporophores
help identification of actinomycete taxa
ACTINOMYCETES:
ecology
ACTINOMYCETES ECOLOGY
• predominantly soil bacteria
• good at degrading recalcitrant
compounds such as chitin & cellulose
• often active at higher pH (contrast to
fungi who may dominate at lower pH)
• give soil the “earthy” smell
ACTINOMYCETES ECOLOGY
Genus Frankia –
--large genus that all form nodules on certain
non-legume trees
--fixes nitrogen from the air and converts into
forms useable by plant host
--involved in “tripartite” relationship with plant
and mycorrhizal fungus.
e.g.
Myrica in the tropics (invasive in Hawaii)
Alnus in temperate climates (early succesional)
Ceanothus in USA (including gardens)
ACTINOMYCETES ECOLOGY
Frankia nodules on Ceanothus roots
ACTINOMYCETES:
antibiotics
ACTINOMYCETES ANTIBIOTICS
• most important genus is Streptomyces over 500 described species!
• produce many important antibiotics, including
Streptomycin - originally from S. griseus.
ACTINOMYCETES ANTIBIOTICS
Other antibiotics produced by Streptomyces spp:
Antibiotic:
Spectinomycin
Neomycin
Tetracyclines
Nystatin
Erythromycin
Chloramphenicol
affects:
M. tuberculosis, N. gonorrhea
Broad spectrum, topical
Broad spectrum, Chlamydias,
Rickettsias etc.
Fungi, esp. Candida
Gram + Bacteria and Legionella
Broad spectrum, typhoid fever
ACTINOMYCETES ANTIBIOTICS
Inability of a test organism to grow in the presence of Streptomyces
suggests antibiotic production by the latter
ACTINOMYCETES ANTIBIOTICS
Fig. 04.18
Fig. 4.18. Secondary metabolites are produced at the end of the
growth phase and during stationary phase….
TUBERCULOSIS:
pathology & history
TUBERCULOSIS PATHOLOGY & HISTORY
• tubercular decay found in spinal
columns of Egyptian mummies
(2400BCE)
• Hipocrates (460BCE) described
“phthisis” as most common disease of
his time
• in 19th century Europe 1/7 of all
deaths attributed to TB
• afflicted famous people such as:
Eleanor Roosevelt, Chopin, Checkov,
Kafka, Robert Louis Stevenson, the
entire Bronte family
• began a 19th century literary genre:
the “tragic lingering death by
consumption” trophe
TUBERCULOSIS PATHOLOGY & HISTORY
TUBERCULOSIS PATHOLOGY & HISTORY
Contraction: inhaling bacteria from
infected person
Primary stage: bacteria isolated by
granuloma in lungs called a
tubercule
Secondary stage: bacteria fail to be
isolated, lesions form in lungs
(coughing up blood)
TUBERCULOSIS PATHOLOGY & HISTORY
tubercules (a type of granuloma) – small, hard
nodules formed when macrophages
surround and phagocytize M.
tuberculosis
TUBERCULOSIS PATHOLOGY & HISTORY
Fig. 23.18
Fig. 23.18.
Inflammatory
response forming a
Tubercle. Note the
lack of nuclei in
dead cells in center
of tubercle.
TUBERCULOSIS PATHOLOGY & HISTORY
Before antibiotics, the only treatment was
rest (to avoid secondary stage)… lead to
many “Sanitaria” (Sanitariums) especially in
mountainous regions with clean dry
air (e.g. Boulder Mapleton Center, near
Mt. Sanitas).
TUBERCULOSIS PATHOLOGY & HISTORY
• Robert Koch (remember him?) was
the first to isolate Mycobacterium
tuberculosis in 1882
• Streptomycin was the first effective
antibiotic against TB (late 1940s) a
little too late for WW2.
TUBERCULOSIS PATHOLOGY & HISTORY
Table 23.9
TUBERCULOSIS:
physiology
TUBERCULOSIS PHYSIOLOGY
TUBERCULOSIS PHYSIOLOGY
•
Mycobacteria all produce mycolic
acids (mycosides) - long-chain “fats” very hydrophobic and wax-like
•
“Slow growing” mycobacteria (such as
M. tuberculosis are so hydrophobic
that nutrients can’t easily diffuse in
•
Mycolic acid is covalently bound to the
peptidoglycan layer of Mycobacteria
TUBERCULOSIS PHYSIOLOGY
TUBERCULOSIS PHYSIOLOGY
Acid-alcohol fast test
binds to mycolic acid.
Good stain for bacteria
too waxy for gram stain
You saw carbolfuchsin in
the Dorner endospore
stain!!
Fig. 23.17. M.
tuberculosis in
sputum sample. Acidfast stain is
diagnostic for
mycobacteria.
TUBERCULOSIS PHYSIOLOGY
Virulence in M. tuberculosis associated with
cord factor
• 2 long chain alcohol groups hooked together by
a disaccharide (trehalose)
• Cause cultures in media to have characteristic
“corded” look
• Cord factor is implicated as causing severe
weight loss in TB patients
• Cord factor is also a virulence factor because
it binds cells of M. tuberculosis together so
that they are further resistant to our immune
system
TUBERCULOSIS PHYSIOLOGY
TUBERCULOSIS:
the disease today
TUBERCULOSIS: THE DISEASE TODAY
• In U.S., about 10,000,000 infected
individuals, many showing few
symptoms
•12,000 deaths in U.S. per year
• very common disease as part of AIDS
and in the homeless population…..
TUBERCULOSIS: THE DISEASE TODAY
Fig. 23.16
TUBERCULOSIS: THE DISEASE TODAY
TUBERCULOSIS: THE DISEASE TODAY
many cases are multi-drug resistant
TUBERCULOSIS: THE DISEASE TODAY
Many patients start feeling better after a month of
antibiotic therapy and stop using antibiotics - which
leads to more drug resistant bacteria. Best solution is
DOTS = direct observation therapy
TUBERCULOSIS: THE DISEASE TODAY
CORYNEFORM BACTERIA
CORYNEFORM BACTERIA
• name comes from “club”: some are
club shaped
• are usually rod shaped (though stay
tuned) and arranged as Vs due to
snapping division
CORYNEFORM BACTERIA
snapping division
• 2 thick peptidoglycan layers
• inner layer of cell wall grows inward to
divide 2 new cells. As it thickens, it puts
tension on outer wall until it ruptures. The
snapping tears the outer wall apart except
at one point which holds the 2 cells
together like a hinge.
Fig. 11.14. Gram stain of a Corynebacterium - note V
shapes
CORYNEFORM BACTERIA
Some important genera of Coryneforms:
Arthrobacter spp. common soil inhabitants
rods when well fed and coccoid cells when
hungry. The coccoid cells are long-lived sporelike cells.
Corynebacterium spp. are common aerobic
organisms of soil. One species, C. diphtheriae
causes diphtheria.
CORYNEFORM BACTERIA
Arthrobacter has a rod-coccus growth cycle
In log phase, they are rods that replicate via
snapping division. In stationary phase, they
are coccoid.
CORYNEFORM BACTERIA
diptheria
• Corynebacterium diptheriae usually
spread by inhalation
• actual invasibility of the bacteria is
minimal
• Produces powerful exotoxin that
damages organs and causes build up
of dead tissue in throat
• Exotoxin only produces if bacteria
are infected with a certain
bacteriophage (virus) and iron levels
to be low
• 1 of 10 diptheria patients die
PROPIONIC ACID BACTERIA
PROPIONIC ACID BACTERIA
Swiss cheese:
•other bacteria (e.g. lactobacilli) ferment
milk’s lactose to lactic acid, form curds
•Propionibacteria then multiply, producing
acetate, CO2 & propionic acid
PROPIONIC ACID BACTERIA
PROPIONIC ACID
BACTERIA
Fig. 06.23
Fig. 6.23
PROPIONIC ACID BACTERIA
Propionibacteria acnes in skin:
• anaerobic bacteria found in hair follicles
(densities up to 107 per square cm of skin)
• growth enhanced by secretions of
sebaceous glands
• under normal conditions, P. acnes is
beneficial: creates low pH skin
environment hostile to pathogens
• when sebaceous gland gets clogged, P.
acnes multiplies in trapped sebum: ACNE!
PROPIONIC ACID BACTERIA
happy hair follicle
BIFIDOBACTERIUM
BIFIDOBACTERIUM
Bifidobacterium bifidus
• anaerobic
• ferments a specific amino sugar and
lactulose (a disaccharide consisting of
fructose and galactose) found in breast milk
• breast milk also contains bifidus factor, an
oligosaccharide that specifically promotes
bifidus colonization
• one of the initial colonists of the intestines
of human babies
• also added to yogurt….
Fig. 11.12
MICROCOCCUS
MICROCOCCUS
•oligate aerobic cocci
•Have high %GC but morphologically dissimilar
to the rest of the high GC gram + bacteria
•usually yellow, orange, or red in color