More on media

I have recently had some more free time and decided to play with various media preparations in hopes of isolating Brett and Lactobacillus species. As I was leafing though the Handbook of Biological Media, I came across this one. Looks like the authors are not without a sense of humor 🙂

Chicken Soup Broth

 

Composition per 5.0L:

Chicken …………………………………………………………………………… 2.5kg

Peppercorns……………………………………………………………………………. 6

Cloves …………………………………………………………………………………… 3

Bay leaf …………………………………………………………………………………. 2

Celery, stalks including leaves……………………………………………………… 2

Onion, large……………………………………………………………………………. 1

Carrot ……………………………………………………………………………………. 1

Dill, fresh ……………………………………………………………………….. 1/4 cup

NaCl …………………………………………………………………………………. 0.1g

 

Preparation of Medium: Add a nice, whole chicken to a large pot. Add enough tap water to cover the chicken by about 1 in. Stud the whole, peeled onion with the three cloves. Add the onion and remain- ing ingredients to the pot. Rapidly heat and bring to boiling. Lower heat to a simmer and cook for 1 to 1.5 hr. Remove the chicken and vegeta- bles from the broth. Remove skin and bones from the chicken. Cut up the meat into 1-inch pieces. Return the meat to the broth. If desired, slice the carrot and celery and return them to the broth.

 

Use: For the growth and nutrition of microbiologists.

 

So don’t forget to eat while you’re up to your neck in the fascinating world of microorganisms 🙂

On a more serious note, I’ve been playing with isolating bugs from raw wort and managed to isolate something that I thought was wild Lactobacillus, but it wasn’t. Whatever it was I threw it out, thought I probably should have played more with it. In any case I still have a sample in my fridge and could just restreak it all. While doing that I was using WYeast’s Lactobacillus that I got from Brooklyn Homebrew as a control and made an observation that it doesn’t grow on agar that contains bromocresol green. I don’t know if it’s something I did, but it consistently refuses to grow on anything with that dye while it overruns the entire plate within two days on the same medium without it.

I have also been playing with lactose agar hoping to fine-tune it for Lactobacillus isolation. As far as I know Brettanomyces annomalus can also metabolize lactose so it could be helpful in differentiating between some strains.

New Glarus dregs are not proving to be too useful yet, but I have hopes for at least something. Anyway, I’ll keep you guys posted.

Cheers!

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6 thoughts on “More on media

  1. Your observation that Lactobacillus can’t grow in presence of bromokresol green might be interesting to selectively inhibit the growth of those organisms. Could be used in isolating Bretts from dregs and inhibit the growth of Lactobacillus? Have you plated other Lactobacillus strains and obtained similar results? Keep up the good work.
    I am thinking of isolating Lactobacillus brevis from my kefir culture. This strain is used in Berliner Weisse brewing because this strain is insensitive to hops. Plated it yesterday on Sabouraud agar. But I will try to add some hops to my agar next time and look for growing Lactobacillus colonies.

  2. You know, this is really interesting. I’m going to make a small batch of agar with hops to check if the selectivity works. I wonder what strain of Lactobacillus the Cascade brewery uses because they say they only use that for souring their beers and those are like 8% abv brews and are EXTREMELY sour. I think I’ll pick up a small bottle and try culturing from it.
    On an even more exciting note, I think my latest medium is playing off. Looks like Lacto colonies turn pink while brett colonies are yellow and Sacch seems not to grow at all or grow extremely slow. Gonna have to let them grow a bit longer and make some slides to confirm, but I’m so so so so excited already! Whoo-hoo!

  3. Keep in mind that there are indeed Lactobacillus strains which are insensitive to hops like L. brevis for example. But please report your results as soon as you have them.
    I guess you are talking about your potato agar when you speak of your latest medium, right? If yes, your observations are quite fascinating. I mean, this would be a very cheap media after all. I am still researching for other media to isolate Bretts out of dregs. I therefore have to use a media which prevents Saccharomyces as in your case, and inhibit Lactobacillus and Pedio. But Pediococcus seems to be a really slow grower, and your bromokresol observation might be the trick to prevent the Lactobacillus… I might use a potato agar and add some bromokresol green.

    I will plate some bugs this afternoon on Sabouraud plates to keep my bug collection alive for further experiments. Will post those results on my page for sure. And I will give your potato media a go and maybe have similar results.

    • Yes it’s the potato base that I’m playing around because my goal is to create media that can be easily replicated at home to help homebrewers. Sure I could use the lab resources and make things that your regular homebrewer would never be able to get his hands on, but that would only benefit me and would essentially be useless for the rest of the community.
      The more I let the colonies grow the more enthusiastic I am about my latest experimental plates. It’s looking promising. Not the answer to all problems, but sure is better than I expected.
      Preliminary results are:
      1. Slows down Saccharomyces growth noticeably, but they pop up eventually after a couple days by which time lacto and brett are happily growing.
      2. Inhibits Brett b.
      3. Brett L and Brett from WY Berliner can be clearly distinguished from other yeast. The latter looks like normal yeast on other plates, but on these it looks like grey cauliflower (same as brett L).
      4. Promotes growth of lactic bacteria very nicely and they are pinkish-white (lacto) or yellow (pedio)
      And the bromcresol green seems to hold true still. Inhibits lactobacillus.
      I plated yogurts and stuff… I’ll post a more thorough description next week.

  4. I am looking forward to more about your homebrewer-friendly media. I haven’t tried culturing brett yet but am anxious to try. I have a mixed culture from a gueuze that should be interesting to plate out.

    Also, thanks for the links to mail order places in that other post. I found some stuff I had been looking for and through some other searches found some of the rest (like bromocresol green from a water treatment shop).

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