Your Home Yeast Lab Made Easy – Streak Plates

The fourth of my “Your Home Yeast Lab Made Easy” series is now up on youtube. This video covers an advanced topic – streak plating. I was not planing on covering this topic so early in my video series, but I was streaking yeast for another project and decided to take advantage of the situation.

Streak plating is used any time you need to purify a strain of yeast (or other microorganism). This method allows you to pull single, genetically pure strains of a microorganism out of a mixed culture. This mixed culture could be any number of sources – an old strain of yeast whose characteristics are starting to drift, a contaminated batch of yeast, a mixed culture (e.g. those made by Wyeast, or from a bottle of sour beer), or even from a wild ferment you started using yeast from your back yard!

The principal of streak plating is simple – a small amount of the source yeast is spread across an edge of a petri dish. The yeast/bacteria/etc concentration in this streak are at a high density, so you swipe a sterilized loop across the first set of streaks, picking up a small number of the organisms, and then streak over another portion of the plate. You repeat this two more times, each time diluting out the yeast/etc further.

3 thoughts on “Your Home Yeast Lab Made Easy – Streak Plates

  • April 13, 2015 at 12:47 am

    I'm just getting the hang of streaking my own plates to isolate wild yeasts for the first time. I'm also excited about being able to bank some commercial strains. While I was streaking today (clothes on this time), I thought, "How would you go about banking a blend?" Can you go straight to a slant, and just take a wider swath with your loop? Is it a better bet to isolate all three (for example), then grow them up in three 7mL tubes, then pitch them all into a 250mL starter? Ideas?

  • December 29, 2014 at 12:49 am

    These videos are superb, I wish this video serie is going to keep growing as I'm really interested in these DIY and low-cost techniques. As a student in Humanities and without a science-related degree, every places I contacted denied me access to their laboratory and equipments and sadly make a large part of natural science elitist. Also, is it possible at all to yeast hunt without any sort of microscope? Thank you!


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