Environmental microbiology Flashcards
what must microbes interact with
-each other and the environment
-Never get a microbe on its own, always present in a community
-We do not fully understand the nature of the interactions
Quorum sensing – just one type of interaction
what is interaction crucial for
microbial cell survival
where is most research taken upon
pure culture
what do individual cells reproduce to form
clonal populations of individual species
-Clonal populations mix and exchange genetic information with members of the same species and members of different species.
Transformation
Transduction
Conjugation
what do species interact to form
communities
what do communities assemble to form
ecosystems
what is the equation for ecosystems
organisms + environment + activities
what diseases can parasitism cause
plant, animal and microbe-microbe diseases
what does predation cause
Nematophagous fungi and Amoebae
what does mutualism cause
-N-fixation in legumes by Rhizobia
-Fungus-plant mycorrhizae
-Human gut microbiome
-Lichen (fungus-alga) symbiosis
what are examples of mixed cultures in nature
-GI tract
-Soil
-Plant roots (mycorrhizae)
-Teeth
what is involved in the traditional strategy for examining bacteria
-Enrichment
-Isolation in pure culture
-Identification= Biochemical tests, Microscopy and DNA sequencing
Relatively slow process
what is involved in the enrichment strategy
- samples include water, soil, human gut contents
-Enrichment medium formulated to support the growth of the desired organisms AND TO ALLOW SMALL NUMBERS TO BE AMPLIFIED
-Isolation medium formulated to support the growth of the desired organisms
what are the limitations to the enrichment strategy
-Many organisms cannot be cultivated so will not appear on the plates yet they may have an important role in the community
-Choice of growth conditions will influence results (bias) e.g. if the plates are incubated aerobically any obligate anaerobes will not be able to grow.
-the selection strategy will always exclude some organisms
what is a disadvantages to cultivation
bias