In an article in Letters of Applied Microbiology, Japanese scientists report that feeding a pickle microbe to mice infected with the flu alleviates the rodents’ symptoms. The scientists previously found that this same bacterium, already in commercial use as a probiotic, can ease acute gastroenteritis caused by Vibrio parahaemolyticus, which sometimes occurs in raw seafood, and irritable bowel syndrome. But the flu results have gotten by far the most attention from the media. UK’s Daily Express, for example, hailed the “New Wonder Cure for Killer Flu.” Picklers around the world may wonder, Is this miracle drug in my pickle crock? Can it cure me of the flu, too?
Actually, the microbe hasn’t cured anybody’s flu. But it did reduce weight loss in infected mice and reduce other symptoms of mouse malaise, such as ruffled fur and lethargy. In other words, the mice treated with the bacterial extract were a little less sick than the untreated ones (that is, until all the mice were forced to inhale enough carbon dioxide to kill them).
The bacterial extract hasn’t been tested in humans. We don’t yet know whether it would alleviate human flu symptoms, and we certainly can’t bet that it would prevent or cure influenza. And we should keep in mind that two of the scientists who wrote the article work for Kagome, the company that markets the microbe, although they declared no conflict of interest. Still, the results are promising.
The name of the miracle bacterium, Lactobacillus brevis, may ring a bell. If you make fermented pickles, you’ve surely cultivated the species. L. brevis predominates in the last stage of fermentation of sauerkraut and brined vegetables. This bacterium is also among the lactic-acid-producing species found in tibicos (water kefir) “grains”; it is, in fact, responsible for producing the polysaccharide gel of which tibicos grains are composed. Among brewers, unfortunately, mention of L. brevis provokes dread, because the species can spoil beer by souring it (although at the moment, oddly, soured beer is nearly as trendy as soured vegetables).
To understand how L. brevis may affect human health is to grapple with the theory of probiotics—that is, live microbes consumed to promote health through their effects in the intestines. L. brevis is one of the lactic-acid-producing bacteria found in healthy human intestines, vaginas, and feces. In recent years scientists have produced plenty of evidence that a healthy immune system depends on a healthy balance of intestinal microflora. When the balance gets out of whack—from the use of antibiotics, from improper diet, or even from emotional stress—we may be able to alleviate the problem by ingesting good bacteria.
Even assuming that the Japanese bacterial extract will prove effective in humans, whether eating pickles will vanquish your flu symptoms is hard to say. First, for L. brevis to be present at all, your pickles must be fully fermented and unpasteurized. Assuming L. brevis is present, it may be slightly different from the strain the Japanese scientists have studied, a strain known as L. brevis KB290. The scientists isolated KB290 strain from suguki pickles, that is, pickled suigukina, a kind of turnip grown near Kyoto. Suguki is one of many traditional Japanese pickles that are identified with a particular city, with particular varieties of produce grown in the region, and even with particular producers. But although the Japanese rightly view suguki as unique, it is made much like other fermented pickles: The turnips are peeled, cut, and briefly salted so that the slices become flexible. They are next packed firmly into buckets, layered with salt, and then weighted. Then they are drained, and they are weighted again until fermentation is complete. They are not enhanced with garlic, chile, or other seasonings. The only really remarkable thing about these pickles is the way they are weighted, using a big stick called a tenbin. Even sans tenbin, fermenting turnips from your garden or local market would probably produce a pickle similar in taste and microbial content to Kyoto’s suguki.
L. brevis would be present in your own turnip pickles, but don’t count on breeding the strain KB290. A strain, to a microbiologist, is derived from a single colony and has been protected from contamination through carefully controlled procedures. These procedures make it possible to test the strain for efficacy and safety and, assuming the strain passes the tests, to market it as efficacious and safe. A strain is not, however, different enough from other strains of the same species to be called a subspecies. And no strain would last in nature. In nature, bacteria undergo continual mutations and lose and gain genetic material. Bacteria thrive in communities made up not only of multiple strains of the same species but of multiple species as well.
Japanese scientists no doubt isolated and tested multiple L. brevis strains before selecting KB290 for marketing as a commercial probiotic. KB290 must have performed better in meeting the requirements of any effective probiotic, for example, in adhering to intestinal cells, in persisting and multiplying, and in producing substances, such as acids, that curb the growth of pathogens. KB290 had to work reliably in all of these ways so it could be marketed on its own, as a drug.
Your pickle crock, in contrast, hosts various strains of L. brevis along with other species of Lactobacillus and fermentative bacteria in other genera, such as Leuconostoc and Pediococcus. Since bacteria are genetically fluid, their diversity is more important to your health than the identity of any particular strain in the crock. Lactic-acid-producing bacteria in naturally fermented foods increases the spectrum of genes available to your intestinal microflora regardless of whether specific strains are able to take up permanent residency in your gut.
So, go ahead and pickle some turnips. Make plain sauerruben, as instructed below, or try my recipe for spicy Korean pickled turnips, sunmukimchi (The Joy of Pickling, 2nd edition, page 67). If you get the flu this winter, eating some of your own pickled turnips just might help you get better faster. In any case, turnips may help keep you healthy generally, especially if you eat the vitamin- and calcium-rich green turnip tops.
Sauerruben
5 pounds turnips, peeled and shredded (with a kraut board, food processor, or grater)
3 tablespoons pickling salt, plus more for the brine
In a large bowl, mix the turnips with 3 tablespoons pickling salt. Pack the mixture firmly into a 3-quart or gallon jar. Push a gallon-size freezer bag into the jar, and fill it with brine made of 1 1/2 tablespoons pickling salt to each quart of water. Seal the bag. Set the jar in a place where the temperature remains between 60° and 75°F.
After 24 hours, check to make sure that the turnips are well submerged in their own brine. If they aren’t, add some fresh brine (1 1/2 tablespoons pickling salt per 1 quart water) to cover them well. If any scum forms within the jar, skim it off and rinse and replace the bag.
After two weeks, begin tasting the sauerruben. It will be fully fermented in two to four weeks at 70° to 75°F, or within four to six weeks at 60°F. When it’s ready, remove the bag, cap the jar, and store it in the refrigerator or another very cool place, tightly covered.
I’ve more than once seen Extension home-ec agents roll their eyes when asked if it’s possible to store sauerkraut in the same jar in which it has fermented, with no heating or chilling. Where do such ideas come from? the agents ask.