What is the principle behind the streak plate method of isolating bacteria?
The principle is to exhaust an initial deposit by making successive smears in different directions (hence the name of the technique: exhaustion by the quadrant method).
What is isolation of 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.
How does the streak isolation technique work?
Principle. The streak plate technique is the most popular method for isolating specific bacteria from a sample containing a mixture of microorganisms. The technique essentially dilutes the number of organisms and reduces their density. It allows microbiologists to distinguish and isolate individual bacterial colonies.
What is the purpose of streaking for isolation?
Streaking for isolation takes advantage of the characteristics of agar and solid media and allows us to physically separate individual bacterial cells so that they each can grow up into discrete, isolated colonies.
What is the purpose of the isolation streak method?
As you might guess, the purpose of streaking for isolation is to produce isolated colonies of an organism on an agar plate. This is useful when you need to separate organisms in a mixed culture or when you need to study the colony morphology of an organism.
What are the isolation techniques?
Isolation practices can include placement in a private room or with a select roommate, the use of protective barriers such as masks, gowns and gloves, a special emphasis on handwashing (which is always very important), and special handling of contaminated articles.
What methods are used for isolation of organisms?
There are two main ways to isolate organisms. Streaking for isolation on an agar plate involves the successive dilution of organisms until you have the cells at a low enough density that single cells are physically isolated spatially to give rise to recognizable individual colonies.
What is the main purpose of the streak plate technique?
The purpose of the streak plate is to obtain isolated colonies from an inoculum by creating areas of increasing dilution on a single plate. Isolated colonies represent a clone of cells, being derived from a single precursor cell.
How do you isolate pure culture from mixed cultures?
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 are the purposes of streaking and spreading plate methods?
Purpose of streaking To produce isolated colonies of an organism (mostly bacteria) on an agar plate. This is useful when we need to separate organisms in a mixed culture (to purify/isolate a particular strain from contaminants) or when we need to study the colony morphology of an organism.
How is the spread plate method of isolation different from the streak plate method of isolation?
The key difference between streak plate and spread plate is that the streak plate is used to isolate and purify a particular bacterial species from a mixture of bacteria while the spread plate is used to enumerate and quantify bacteria in a sample.