Microbial Communities Flashcards
Examines interactions between species in groups over
a wide range of temporal and spatial scales, including
distribution, population dynamics, structure,
abundance, and demography
community ecology
community ecology is also called
synecology
important aspects of microbial communities
community boundary
community structure
community strucrture can be described by
❑Species makeup
❑Species richness
❑Species relative abundance
an assemblage of microbial cells that is irreversibly
associated (not removed by gentle rinsing) with a surface and
enclosed in a matrix of primarily polysaccharide material
biofilm
Structured communities of
one or more species of
microorganisms.
biofilm
biofilm produces a community of members of a matrix characterized by a ___
hydrogel
a key stage in the biofilm lifecycle, involves the transition from initial microcolonies to a complex, three-dimensional structure, characterized by increased cell density and the production of an extracellular matrix (EPS
biofilm maturation
adhesive structures in biofilm formation
PIA
eDNA
proteins
disruptive factors in biofilm formation
proteases
nucleases
PSMs
- considered a specialized type of
biofilm.
biomats
range from several millimeters to a
centimeter thick, and are vertically
stratified into distinct layers versus
biofilms which are typically one to
several cell layers thick
biomats
microbial
groups are tightly compressed into a
thin mat of biological activity)
biomats
commonly associated with aquatic
habitats, including hot springs,
hypersaline ponds, and intertidal
coastal zones and oligotrophic
environments
biomats
first layer of biomat
microalgae
second layer of biomat
cyanobacteria and diatom species
(oxygenic phototrophs, aerobic heterotrophs
3rd layer in biomat
purple sulfur and green sulfur bacteria (anoxygenic phototrophs
anaerobic heterotrophs)
fourth layer in biomat
sulfate reducers
methanogens
iron sulfide rich sediments
Sedimentary layer, CH4 and H₂S formation
which layer
sulfate layers, methanogens, iron sulfide rich sediments
- It is the regulation of gene expression in response to
fluctuations in cell-population density.
quorum sensing
- Quorum sensing bacteria produce and release chemical signal
molecules called
autoinducers
that increase in concentration
as a function of cell density
autoinducers
gene expression produces
rna and protein
study quorum sensing and explain it
Lux Quorum Sensing in Vibrio fischeri
Autoinducer Production:
The process begins with the production of an autoinducer molecule, specifically N-acyl homoserine lactone (AHL), synthesized by the enzyme LuxI.
As the bacterial population grows, the concentration of AHL increases in the environment.
Detection and Activation:
When the concentration of AHL reaches a threshold level, it binds to the LuxR protein, a transcriptional activator.
The LuxR-AHL complex then binds to the promoter region of the lux operon, activating the transcription of genes responsible for bioluminescence.
Bioluminescence:
The lux operon includes genes such as luxA and luxB, which encode the α and β subunits of luciferase, the enzyme that catalyzes the light-emitting reaction.
Additional genes, luxC, luxD, and luxE, are involved in synthesizing the fatty aldehyde substrate required for the bioluminescent reaction.
Regulation and Efficiency:
The system ensures that bioluminescence occurs only at high cell densities, making it an energy-efficient process.
This mechanism allows Vibrio fischeri to produce light in a synchronized manner, which is beneficial for symbiotic relationships, such as with the Hawaiian bobtail squid
Quorum sensing is also
important in:
toxin production
antibiotic resistance
virulence factor
population
competence
conjugation
sporulation
motility
- are signaling molecules that are
produced in response to changes in cellpopulation density
autoinducers
(as the density of
quorum sensing bacterial cells increases
so does the concentration of the
____)
autoinducers
- allow bacteria to communicate both
within and between different species.
autoinducers
This communication alters gene
expression and allows bacteria to mount
coordinated responses to their
environments, in a manner that is
comparable to behavior and signaling in
higher organisms
autoinducers
is the enzymatic degradation of molecules
used by bacteria for synchronizing their behavior within communities
quorum quenching
has attracted wide attention due to its potential to inhibit biofilm formation
and suppress the production of virulence factors.
quorum quenching
- Microorganisms rapidly recolonize these barren surfaces, coming from
surrounding areas, blown in on air currents, carried in on animals and
plants returning to disturbed areas called
immigration and recruitment
recovering from remnant populations
regrowth
- Natural environment where colonization and recolonization can occur
- Freshly cooled lava
- Newborn’s GIT system
- Emergent leaves
artificial environments where microbes can colonize and recolonize
Medical devices
* Implants
* Transplants
* Built environments
is the number of different species in an area, it is a key
measurement used to assess the variety of species in an
ecosystem
species diversity
is the number of different species in a given area or ecosystem
species richness
is the number of individuals of a species in a given area.
species abundance
- the proportion of a particular type of organism in a community
relative to the total number of organisms in that community
relative abundance
is the difference between the number of microbes seen under a microscope and the number that can be grown in a lab
thre great plate cont anomaly
Microbes play multiple important functions in Earthian
processes
element cycling
decomposition
infections
s can be revealed in phylogenetic trees
- getting a handle on this vast diversity can be
accomplished through the use of diversity indices
evolutionary events
- Is a quantitative measure that reflects how many
different types (such as species) there are in a
dataset (a community).
diversit indices
best example of diversity indices are
shannon-weiner diversity index
simpson diversity index
- It is the movement of organisms across space and time.
dispersal
It is the process by which the mix of species and
habitat in an area changes over time
ecological succession
occurs in newly exposed or created areas without life (like volcanic rock),
primary succession
happens in areas where life existed but was disrupted, with soil already present.
secondary succession
An ecosystem capable of returning to its equilibrium state after
a perturbation or does not experience unexpected large
changes in its characteristics across time.
ecological stability
refers to an ecosystem’s ability to remain relatively unchanged when faced with disturbances
resistance
refers to an ecosystem’s capacity to absorb disturbances and maintain its fundamental functions and structures, ultimately returning to its pre-disturbance state.
resilience
efers to the degree to which ecosystem properties or functions remain consistent over time, often measured as the inverse of the coefficient of variation
temporal stability
involves assisting ecosystems to return to a stable state after damage or degradation, whether through natural processes or active intervention
ecological stability
