Definition: the study of the behavior and the activities of
microorganisms in their natural environments Foundations o
populations
assemblages of similar organisms o communities
mixtures of different populations o ecosystems
self-regulating biological communities and their physical
environment
Interaction beetween microorganis
Netralism
Sinergism
Simbiosism
Competism
Antagonism
Parasitism
Neutralism
there is no any physiological effect between
the populations.
Commensalism Commensalism is a unidirectional relationship
betwen populations in which one population benefits and the
other one isunaffected.
Synergism
Synergism indicates that both populations benefit from the
relationship but the association is not obligatory. Both
populations are capable of surviving independently.
.
Mutualism Symbiosis Mutualism Symbiosis is an obligatory
inter-
relationship between two populations that benefits both of
them.
Lichens is composed of a fungus and an alga.
Competition
Competition occurs when two populations are striving for the
same resource of nutrients or the habitat.
Antagonism Antagonism occurs when one population
produces a substrate inhibitory to another population.
Parasitism
the parasite population is benefited and the host population is
harmed.
Synergism
Antagonism
Symbiosis
Commensalism
Mutualis
Parasitism
Commensalism
Definition Relationship in which one symbiont (the commensal)
benefits while the other (the host) is neither harmed nor helped.
Characteristics Spatial proximity The commensal feeds on substances
captured or ingested by the
host. The commensal obtains shelter from the host Not dependent
on the host metabolically Examples E. coli (the commensal) lives in
human colon (the host) E. coli use up O2 and benefits Bacteroides
sp (obligate
anaerobes)
Oppurtunism
Opportunistic pathogens
members of normal microbiota that produce
disease under certain circumstances
Opportunistic infection definition:
infections caused by organisms that usually do not cause disease
in a person with a healthy immune system, but can affect people
with a poorly functioning or suppressed immune system. They need an
opportunity to infect a person
