Lab 3 - Ubiquity Flashcards
where are microbes found?
everywhere - soil, water, organisms, etc.
why don’t microbes take over the world?
because they have to be given the right chemical (nutrients) and physical (temperature, pH) conditions.
what happens if the microbes have the right chemical and physical conditions?
The microbes can increase in number rapidly (example, 1 E. coli cell multiplies to form a million cells in less than 8 hours)
what are good and bad cases of rapid growth of microbes?
bad - in case of pathogens/food spoilage microbes.
good - in case of culturing microbes in lab for studies.
what is broth? and an example?
liquid growth medium, example: nutrient broth (NB)
growth of microbes in broth is called…?
growth in broth can be visualized as cloudiness or turbidity
when can turbidity be seen?
when microbes reach a density of 1 million cells per ml
what does a lack of turbidity mean?
means absence of growth
what is agar? and an example?
a solid growth medium, example: nutrient agar (NA)
how do you convert a broth growth medium to an agar growth medium?
when you add a thickening agent called agar to a broth, it turns into agar
what did they used to add instead of agar to make a broth an agar?
gelatin
what are the two advantages of agar over gelatin?
- It is enzyme-resistant (it is a polysaccharide that microbes can’t eat)
and - it is heat-stable (it is liquid when hot and solid when it cools down)
who discovered agar?
Angelina Fanny Hesse
what is growth on agar called? how is it visualized?
growth on agar can be visualized as colonies
what is a colony?
a cluster of microbes
why are the vast majority of microbes non-culturable?
because the growth requirements are unknown; we know they exist because we can detect their DNA using techniques like PCR
we interact with microbes by what two things?
transient exposure and colonization
what is a normal microbiota - mutualistic?
a mutualistic relationship in which both the partners benefit - the host and the microbe (+/+)
what is a parasitic relationship?
a harmful relationship when the parasite benefits but the host is harmed (+/-)
what happens when the microbiome is displaced?
if displaced to another location, the normal microbiota can become parasitic
what is an example of a displaced microbiota?
when E. coli is the colon is displaced to the bladder causing a UTI
what is a commensal relationship?
displays a type of relationship where one partner benefits and one remains unaffected (+/o)
how would you turn a yeast extract broth to a yeast extract agar?
by adding agar
is it possible for a single bacterial species to have 2 different ecological relationships with people?
yes, it can be mutualistic in one part of the body but parasitic in a different part of the body.
T/F: we use a variety of different agars in the lab to provide different sources of nutrition to bacteria
False; the agar isn’t different. the liquid is
