Fred Transplant: Success!

A Gram-stained view of yeasts and bacteria in a sourdough culture named 'Fred'.

I had to do a Fred Transplant last week. A grey fuzzy mold had taken up residence in on the sides of the jar above Fred’s liquid culture, so I set up a fresh container with fresh water and flour, and dipped a spoon down the center of Fred to the bottom, pulling up just a tiny amount of the stuff in there. Then I mixed it into the fresh stuff and covered it with plastic wrap (instead of a paper towel this time.)

Fred smells like Swiss Cheese Feet right now, but he’s obviously still growing, as you can see from last night’s “Gram Stain” microscopy. The slightly blurry light-red-brown lumps are, I believe, yeast cells, possibly Saccharomyces boulardii, since I dumped a capsule of supposedly-still-viable “probiotic” yeast of that species into Fred previously. I have no idea who the bacteria are in here at the moment. I did also see a small number of longer, thinner bacterial cells in there (presumably Lactobacillus) though most of them are the ones you see here.

Meanwhile, I’m about to dig out the still-unused Hillbilly Autoclave and try it out on the media I’m mixing up to try to obtain a culture of genuine wild “native flora” vinegar/kombucha yeast-and-bacteria to play with from the local wildflowers that are just now getting into full bloom.

My starting recipe goes something like this: I mix up about 2 Liters of distilled water with about 100g of glucose (“Dextrose”/”Corn Sugar”), 100g of sucrose, 500mg of L-Arginine, and enough phosphoric acid to drop the pH down to about 5.5 to 6.0. That is intended to be then poured into small “canning” jars in about 100ml amounts and pressure-cooked for at least 15 minutes to sufficiently sterilize and seal them. Meanwhile, a single generic-brand children’s chewable vitamin is crushed up and dumped into a 4-oz bottle of cheap vodka and well shaken.

Then when it comes time to go bioprospecting, I’ll pop open the jar of acidic sugar solution and add about 5ml of the cheap-vitamin-vodka to it to give me about 2% ethanol, and then go find some flowers to cut off and dump into the jars, which will be loosely covered with foil (to let air in but keep dust out) and put in a nice quiet cupboard to grow for a few days.

Hypothetically, the only things that are likely to grow in that will be microorganisms associated with vinegar-making. At some point I’ll also make up a batch of sweet black tea and see if I get a kombucha-like culture going in it, and make up some solid media to try to isolate individual microbes from it.

Fermentation: not just for alcohol

What does gluconic acid taste like, anyway?

Well, that was an interesting reminder. I’m tracking “fermentation” on Twitter, and caught a random reference to an interesting fermented beverage being made in Germany. The “reminder” I drew from this serendipitous reference was that “fermentation” doesn’t necessarily mean alcoholic fermentation.

“Fermentation” seems to be slightly tricky to define accurately. Most definitions seem to directly mention alcohol production from sugar, but this is only an example and not a definition. I’ve also seen the term used to mean simply “to grow a culture of microorganisms” (because the tank they are grown in can be referred to as a “fermentor”.)

Properly speaking, fermentation is what you get when you have microbes growing under conditions where the elelectrons that get sucked away from “food” molecules like sugars ends up on another, simpler carbon compound rather than something like oxygen, and therefore fermentation is implicitly anaerobic although that’s not the same as saying that fermentation cannot happen in the presence of oxygen (e.g. the Crabtree Effect, and of course fermentation of ethanol to vinegar requires oxygen). The end product is generally assumed to be organic acids (like acetic acid [vinegar]) or alcohols, and carbon dioxide. So, making beer and wine is fermentation. Making vinegar is fermentation. Making yogurt (lactic acid) is fermentation. Citric acid can be made by fermentation of glucose by Aspergillus molds, as can malic (apple) acid (see US Pat#3063910). You can make tartaric (grape) acid from glucose by fermentation as well (see US Pat#2314831).

I am familiar with the flavors of all of those products. One I’ve never directly tasted is gluconic acid, which is the main product of the fermentation process used to make “BIONADE®” (it seems to be written in all-caps everywhere).

According to their English-language page discussing their process – linked from the image at right, click to view – they are starting with malt, just as one would for beer, but instead of Saccharomyces yeasts, they are fermenting this wort-like liquid with “acid bacteria”. I’m going to hazard a guess that the bacterium in question is a strain of Gluconobacter oxydans or one of its close relatives. This group of bacteria is in the Acetobacteraceae family of bacteria which is involved in turning your wine into vinegar. It would appear that under the right conditions, the enzyme Glucose Oxidase (EC produced by G.oxydans converts glucose to a compound which reacts with water to form gluconic acid. BIONADE® then adds flavor extracts and juices to the filtered fermentation product, carbonates it, and bottles it.

Not being familiar with the flavor of gluconic acid, I’m aching to get my hands on some of this stuff and try it.

For another example of a relatively non-alcoholic fermented beverage, see also Kombucha, which is essentially sweetened tea fermented by acetic-acid bacteria and non-Saccharomyces yeasts…which I also have yet to taste.

geostr:50.4600,10.2208:200804110105-06:geostr (at least if Google Maps interpretation of the address I could find at the moment is correct, and assuming the information I dug up and my interpretation of it is correct, this should be the approximate location of the brewery responsible for BIONADE® production.)