How to Isolate Bacteria, Archaea or Fungi from Soil.
This is a method to isolate soil living organisms like bacteria and fungi from soil.
Isolated soil organisms can be used to create special blends of symbiotic life for organic fertilizers, seed treatments, biological pesticides and much more.
Start with a fresh agar dish, and a clean work space with a lamanar flow hood or similar clean air equipment. Use the recipe you feel is appropriate for the organisms you wish to grow. (Ex. potato dextrose or malt extract for some fungi, or a nutrient broth recipe for bacteria) Do not use ‘blood agar’, as it grows pathogens very well
Working in clean air, add a small scoop of soil onto one quarter of the dish.
This quarter of the dish is now Q1. Move your wire loop through the pile one time and then in a zig zag across Q1 without crossing any of the lines you make. This will spead the sample out into a thin line decreasing the likelihood that colonies will grow to close to each other to be separately sampled.
Clean your wire loop (by heating it with a flame) and then swipe one time through the last line in Q 1 onto the next quarter of the plate Q2.
Clean your wire loop and swipe across your mark in Q2 in a zigzag pattern across Q2 like you did in Q1.
Repeat steps 4 and 5 to Q3 and Q4, be sure to clean your wire loop between each step.
You have now spread your sample thinly across the petri dish, close, seal with parafilm and incubate the dish until small dots start to form on the agar, these are colonies of fugi, bacteria, or archaea. (Warning at this Step you will have colonies that could be potentially toxic or pathogenic. This makes the dishes a serous biological hazard, although most cultures are harmless exposure to specific cultures, especially in high concentrations could possibly kill you or make you very sick. Look at the colonies, identify them, and then proceed with extreme caution)
If the colonies are not spread out enough in Q4, start over with a smaller starting sample and spread a smaller amount to each quarter of the dish.
Sample the colony you want and transfer it to the center of a fresh petri dish.
Incubate the sample untell it starts to grow a large colony.
Inspect the colony with a microscope. If the sample comes out clean congratulations, if not your need to run a race to separate your preferred organisms.
Place a sample from the contaminated dish in the very center of a new dish
Sample the new growth on the edges of the colony as it expands, and place it on a new dish. If your selected organism is able to grow faster than its contamination on your media, then the sample you take from the edge will create a clean culture.
If your sample is still contaminated Repeat steps 9, 10, and 11 with different agar recipes and additives. Until you are able find a combination that allows your chosen organism to outgrow its contamination so you can create a clean culture.
Store your cultures, use them to create a liquid culture, or use them for other experiments.
If you have questions, or need more information contact us to set up a meeting with our biologist Tanner Wycoff.
