BIOL240 Lecture Notes - Lecture 9: Lactobacillales, Myxococcus Xanthus, Intracellular Parasite

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14 Aug 2016
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Microbiology Notes: Week 9: Bacteria II
Definitions:
Lecture Notes:
- Vibrio, Rickettsias, and Spirilla:
oVibrio and Photobacterium,
Vibrio is an important human pathogen,
Gram-negative, facultative aerobic rods,
Found mostly in aquatic environments,
Vibrio cholera is human pathogen which causes cholera,
Disease is usually associated with poor water sanitation.
Also a number of Vibrio strains that aren’t pathogenic,
oSome of these organism are bioluminescent and associated
with fish
Bioluminescence requires the luciferase enzyme,
which is produced as a result of gene expression at
high population concentration
oRickettsia:
Most are obligate intracellular parasites,
Infect both humans and animals,
Closely related to mitochondria,
Only replicate within their host cells,
Mitochondria evolve from organisms that probably had similar relationships
with their host cell,
Causes the diseases Rocky mountain spotted fever, Q fever:
oRestricted energy metabolism, many of these organisms can
only use glutamine and glutamate as nutrients which they
acquire from their host,
oOften transmitted by arthropod vectors, as insect feeds on the
blood of the host it’ll also ingest some of the cells in the blood
stream that will proliferate within the blood stream and will be
re-transmitted when insect feeds into another host.
oSpirilla:
Organism that are classified based on their spiral cell shape but they’re very
phylogenetically diverse grouping,
Have members of all 5 subdivisions,
Scattered in the protobacteria,
Bdelovibric:
Organism that will infect other gram-negative bacteria, often look like
bacteriophage infections when they’re caused by bdelovibrio
oOften can’t live outside the host, attaches to the prey bacteria
and goes into the periplasmic space where it will replicate and
grow within that space,
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oCan only affect gram-negative organisms.
- Budding and Stalked Bacteria and Gliding Myxobacteria:
oBudding and stalked:
Grouped based together on their cell type or division.
Unequal cell division in which the division occurs in one region of the
cell where a bud forms.
Most are alpha but some beta and gammas.
Will often have extrusions from the cell,
Sometimes have holdfast that help keeping the organism attached to the solid
surface.
Often have 2 cell types
oUnequal Cell Division:
Binary fission: have a rod shape that elongates, a septum forms and they
break apart where they have two identical cells,
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Polar growth: growth of only one part of the cell, get a blubbing off of the
bud where you’d get two cells. One would be a daughter cell, one would be a
parental cell,
Simple bud: smaller bud that grows which results in a formation of a daughter
cells.
Budding from hyphae: it elongates and then a bud forms where it buds off
and separates,
Cell division of stalked organism: Claubacter: can give rise to a swarmer cell.
oStages of the hyphomicrobium cell:
Start off with a mother cell, the first thing that happens is that a hypha will
form as it is forming and lengthening you get dna rep so it can divide. A copy
of the dna chromosome enters into the hypha and goes towards the bud which
is starting to form at the end, once it has the chromosome in the bud, it can
continue to grow and divide into a swarmer cell which has the ability to turn
back into a mother cell.
oStages in the Caulobacter cell:
The stalked cell is the only one that can divide, so the swarmer cell loses the
flagella so a stalk is formed, it then can bud off a swarmer cell which is
motile again.
oGliding myxobacteria:
Quite complex,
Can communicate with each other and their development is dependant on
this,
Has very large chromosome because of their complicated developmental
process,
Simple vegetative cells have gliding motility, and are often found on solid
surfaces,
Typically get nutrients by lysing other types of bacterial cells.
Under starvation conditions, the cells can differentiate and form fruiting
bodies.
The myxospores within the fruiting bodies are resistant to desiccation.
Most are members of the delta,
Fruiting bodies are made up of aggregations of the cells of a different type
found in the stalk.
Can be classified because of their fruiting body.
oLife-cycle of the Myxococcus Xanthus:
Usually are a vegetative cell (all the same, gliding, lysis bacteria) , but if they
need nutrients they can start swarming together and are aggregated- there are
specific signals that show the populations that they’re nutrient limited which
results in the aggregation and cultivation of the cells, some form the
myxospores and some from the stalk. The fruiting body becomes myxospores
once again and once they’re in better form, the myxospores can germinate
once again would be back to their vegetative state.
- Nonsporulating:
oThe gram positive bacteria are divided into two sub groups,
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