How do you prepare a pure culture from a mixed broth culture?

Answer 1

There will never be a pure culture in this system of things. However, depending on what you believe in of course, there is to come a time when all the disturbing mixed up things we deaql with on a daily basis will come to pass and a new earth will form. It will be at that time when we can truly obtain a pure culture. Just my opinion, take it for what it is, but know I'm basing it on over 30 years of theocratic study. Have a blessed day.

^ This person is a retard, it's a microbiology question, they aren't referring to a culture of people, they are referring to a culture of microbes.

And it took me 2 seconds to look up the real answer.

So:

A mixed culture is a mix of different strains of an organism / bacteria.

A pure culture is a culture consisting of only one strain.

YOU CAN OBTAIN A PURE CULTURE BY PICKING OUT A SMALL PORTION OF THE MIXED CULTURE(which will form the pure culture) AND GROWING THEM ON A NEW CULTURE MEDIA.

It's like taking 2 animals out of a herd and breeding them, and breeding only within their family, so they all look exactly the same. Except bacteria can reproduce asexually so you just need one.

Answer 2

There are different methods in preservation of microbes as: periodic transfer, mineral oil slant, minimal medium distilled water, or water agar, freezing in growth media, drying, lyophilization, ultrafreezing

Answer 3

This is done in a step wise manner:

Part I: Obtaining Bacterial Samples

Determine beforehand where you'd like to sample for bacterial cultures. Make sure you get permission, and discuss what kinds of bacteria you might expect to find in each location. At each location, put on a pair of gloves. Dip a sterile swab into the dirt, water, or other substance to be sampled. Lightly rub the end of the swab onto a sterile agar plate like you're painting a line onto the surface of the agar. This will give you a mixed culture of microbes. Carefully dip the same swab into your water-filled tube - this will give you a backup in case your first plate culture doesn't work out.

Mark your plate with the date, location, and your initials to keep track of your culture.

Part II: Isolating a Pure Bacterial Culture

From the line streaked onto the surface of your plate (the mixed culture of microbes), you can try one of two techniques to separate them: Use a second sterile cotton swab or a sterile toothpick to touch a portion of the line on your plate and gently streak it across the plate in a zigzag pattern. Or:

Back at the lab, take a sterile inoculating loop (loop is made sterile by passing it through flame from Bunsen burner then cooled) and dip the loop into the culture of microbes. Then streak this in a pattern over the surface of the agar plate. The inoculating loop is sterilized following each streak series. As the pattern is traced, bacteria are rubbed off the loop onto the medium. The last cells to be rubbed off the loop should be far enough apart to grow into isolated colonies. Streaked plates are then incubated overnight at 37 degrees Celsius. Selected colonies can then be picked up from these plates with a sterile inoculating loop and transferred to separate agar plates or culture tubes (such as typtic soy agar slants or tubes filled with Luria broth) to form a pure culture. Once you have obtained a pure bacterial culture, you are ready to stain your microorganism.

Part III: Staining Bacterial Colonies

After pure culture is obtained, microorganism is fixed to a microscope slide using an inoculating loop as follows: flame loop then allow it to cool, dip loop into pure culture medium then smear it onto microscope slide. Allow smear to air dry. Smears can also be heat fixed by carefully passing the slide through flame. Cover the smear with crystal violet dye for 30 seconds. Because the purple stain imparts its color to all cells, it is called a primary stain. Rinse the purple dye off with distilled water then cover the smear with Gram's iodine for 10 seconds. Rinse gently with distilled water. Decolorize the smear with alcohol. Rinse with distilled water then cover the smear with safranin for 30 seconds. Rinse the smear with distilled water and blot the slide dry. Observe slide under a microscope. Bacteria that are gram negative will appear pink while those that are gram positive will appear purplish.

Answer 4

by making the culture selective eg:

1- make it highly alkaline"vibrio from stool"

2-increase salt concentration"eg for staph"

3-increase bile concentratin"eg Mconckey for enterobacteriasae"

4-adding antibiotics that the organism of interest is resistent to, but kill other microorganisms"thayer martin agar for Neisseria gonorrhea

Answer 5

The three-phase streaking pattern, known as the T-Streak, is recommended. The streaking is done using a sterile tool, such an inoculation loop. The loop is first sterilized by passing it through a flame.
When the loop is cool, it is dipped into a specimen containing many species of bacteria. The loop is then dragged across the surface of the agar in a back and forth in a zigzag motion until about 30% of the plate has been covered.
The loop then is re-sterilized and the plate is turned 90 degrees.
Starting in the previously streaked section, the loop is dragged through it two to three times in continuing the zigzag pattern. The procedure is then repeated once more being cautious to not touch the previously streaked sectors.

Each time the loop gathers fewer and fewer bacteria until it gathers just single bacterial cells that can grow into a colony. There will be several single colonies of one type of bacteria.

Answer 6

Pick of a single colony from the mix, ensuring you get none of the other colonies and using aseptic technique, spread it out on another plate. Incubate and wait for growth.