Lab #3: Streak Plate, Culture Transfer Instruments and Techniques, Isolation and Maintenance of Pure Culture

Lab #3: Streak Plate, Culture Transfer Instruments and Techniques,

Isolation and Maintenance of Pure Culture

Introduction

                  Microorganisms are basically everywhere in the environment. Like us, they are generally living as a giant mix of population or communities. However, in our case we want to single out the bacteria on focus on one at a time. In order to do this, one has to isolate each bacteria into pure cultures. Another words we have to differentiate each type, we can do this by using a selective or differential growth media. This will differentiate the bacteria into selective areas or colors for you to single out. Now the fun part… Once you have isolated the selected bacteria you want to study then you can literally pick it up with a toothpick and incubate it in some LB broth. This multiplies the bacteria exponentially allowing you to harvest if you feel like being evil and freezing them for later use then that’s also an option.

Methods and Materials

                  Before working with your microbes, your work space must be nice and sanitary. Mainly for not contaminating your culture but also because your partner may be dirty and smell bad. Who knows! But anyway, you have to slap on your rubbers like your local doctor and sanitize your lab table with college kids best friend (Alcohol). This allows you to not contaminate your culture and keeping it that pure culture you spent so much time growing. So grab some paper towels and at least 70 percent ethanol (not recommended in drinking) and wipe down your table as well as your gloves.

                  Now you are ready to streak some plates! Use a sterile toothpick and your frozen stock of cultured microbes and give it a dip. Use a spreading technique shown below on a sterile dish provided usually by a nice lab guy. You will need about three to four toothpicks, each time dragging your microbes along the dish with a jelly like substance you set up for them. This is how it should look

Figure 1. Streak Plate Technique Methodology. Source: http://www.personal.psu.edu/faculty/k/h/khb4/enve301/301labs/lab4pureculture.html

                  Now that you plated the little guys, you have to incubate them at a temperature of about 37 degrees C for around 24 hours. Now after time has passed and so has your patience then remove from the incubator. Use another toothpick and pick up a nice lonely isolated colony and swirl it in a sterile flask with some yummy LB broth (liquid). Throw it back it an incubator at 37 degrees C for 24 hours, however add a spin of about 100 rpms to it so it gets a nice mix.

                  Now you can use the incubated microbes in the LB broth as a growth curve. Use a sterile pipette tip and transfer 1 mL of culture to a flask of sterile broth. This allows for the growth curve to begin. If a frozen stock sparks some interest then combine 1 mL of the log phase E.coli with 1 mL of glycerol (stops from killing the cells) in a cryogenic tube at 80 degrees C below (-80).

We are beautiful 

Results

                  This is still a set up lab for a future lab so no results just yet, stay tuned for results.

Discussion

                   As a personal note, do not tear the gel-like substance that was made previously when applying your frozen culture with a toothpick. This is very easy to do so don’t go at it like a mad man like me.

                  Don’t forget to add glycerol to your culture if you want to freeze them for later use. If you forget then this will kill them all and all that time was wasted for nothing.