Obtaining a pure culture of bacteria is usually accomplished by
spreading bacteria on the surface of a solid medium
so that a single cell occupies an isolated portion of the agar surface. This single cell will go through repeated multiplication to produce a visible colony of similar cells, or clones.
How do you isolate a pure culture?
A pure culture may be isolated by
the use of special media with specific chemical or physical agents that allow
the enrichment or selection of one organism over another. The differential and selective procedures will be utilized later in this course.
What makes a culture pure?
A pure (or axenic) culture is
a population of cells or multicellular organisms growing in the absence of other species or
types. A pure culture may originate from a single cell or single organism, in which case the cells are genetic clones of one another.
How can you identify a pure culture?
A pure culture contains only one single type
; a mixed culture contains two or more different bacteria. If a bacterial culture is left in the same media for too long, the cells use up the available nutrients, excrete toxic metabolites, and eventually the entire population will die.
Why do you want to obtain a pure culture?
The importance of having a pure culture, and not a mixed culture, when performing biochemical testing is that
a pure culture may react much differently in isolation than when it is combined with other species
. Bacteria replicates at infinitesimally long rates and one species may enforce or weaken the other.
What is the first thing you do to obtain a pure culture?
A pure culture is usually derived from a mixed culture (one containing many species) by
transferring a small sample into new, sterile growth medium
in such a manner as to disperse the individual cells across the medium surface or by thinning the sample manyfold before inoculating the new medium.
What is the difference between pure culture and mixed culture?
A pure culture contains only one single type; a
mixed culture contains two or more different bacteria
. … Microbiologists use subculturing techniques to grow and maintain bacterial cultures, to examine cultures for purity or morphology, or to determine the number of viable organisms.
Can you visually see if your culture is pure?
You can determine if a broth culture is pure ( all one species of bacteria
How can you purify culture?
Using the
streak plate method
of isolation, obtain isolated colonies from a mixture of microorganisms. 2. Pick off isolated colonies of microorganisms growing on a streak plate and aseptically transfer them to sterile media to obtain pure cultures.
Do your slants contain pure cultures?
Do your slants contain pure cultures? How would you confirm their purities? Yes, you would confirm by
using the method of Gram staining
and looking at the microorganism under the microscope. In regard to bacterial growth on solid media, define the term colony.
What does mixed culture mean?
Mixed-culture fermentations are
those in which the inoculum always consists of two or more organisms
. Mixed cultures can consist of known species to the exclusion of all others, or they may be composed of mixtures of unknown species.
What is the purpose of isolating pure cultures?
The isolation of bacteria in pure culture is important because it facilitates the
application of recombinant DNA technology through the isolation of clones
.
What are culture methods?
Culture methods involve
taking samples from the field and detecting the presence of microbe by culturing them
. From the amount of microbial species their influence on corrosion is estimated. Culture media to grow different microbes have been established.
Is Broth a pure culture?
Can broth cultures be pure?
Yes
, if only one type of microorganism is present. You just studied 14 terms!
Can a pure culture be prepared from a mixed?
Can a pure culture be prepared from a mixed-broth or a mixed-agar-slant culture? Explain. Yes, the components from
the mixed culture just need to be separate first
. This can be done by doing a streak plate or diluting the mixture and using a spread-plate technique.
Can you tell by looking at broth culture if it was contaminated or not?
It’s nearly impossible to tell
if a liquid culture is contaminated as few bacteria make pigment in liquid broths as well as the fact that all bacteria would make the liquid look cloudy.
