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What Are Spore-forming Cultures / Probiotics?

While probiotics are certainly nothing new, interest in supplements containing beneficial bacteria has increased sharply during the past decade. This rise in popularity has been a boon for probiotics as a thriving category, sparking a great deal of additional research into the human microbiome and a better understanding of the types of bacteria that live within the gut. Despite a rise in public awareness, however, most people are only familiar with a very specific type of probiotic—they know very little (if anything at all) about spore-forming cultures.

If you’ve never heard of spore-forming probiotics, you’re certainly not alone. They’re also referred to as “soil-based organisms,” or “SBO.” Read on to learn more about how SBOs relate to probiotics, and if they might be worth considering.

What are SBOs?

First, it’s important to understand the makeup of most probiotics that are sold in supplement form. The majority of probiotic supplements are derived from lactic acid; bacteria that already lives within the gut and are essentially “native” to the human body. While effective and often considered a “one-size-fits-all” approach for a variety of ailments affecting the gut, lactic acid-based probiotics are limited in certain ways — most notably in their inability to properly withstand the degrading effects of stomach acid.

Spore-forming probiotics are an entirely different type. Unlike most probiotics, these bacteria aren’t naturally found within the gut. Instead, these strains of Bacillus are found scattered throughout the environment in places such as soil, rocks, dust and vegetation — they can even be found in aquatic environments. Because of a unique protective layer, the inner spores of these bacteria are kept safe from environmental factors, allowing them to survive for years, decades and even centuries while lying dormant.

Many of these bacteria strains are available in supplement form, including Bacillus clausii, Bacillus indicus, Bacillus coagulans and Bacillus subtilis.

How Are Spore-Forming Probiotics Different from Lactic Acid-based Probiotics?

Traditional, lactic-acid based probiotics and spore-forming probiotics share an important piece of common ground—they are both beneficial, live microorganisms that can help to improve overall digestive health and bolster the immune system when taken in supplement form. The key differences lie in when SBO-based probiotics and lactic acid-based probiotics enter the body, specifically, how each handles the harsh conditions in the stomach. Lactic acid-based bacteria are light-sensitive and often require constant refrigeration for live active culture preservation, so when entering the stomach, have a very difficult time making it through to the intestines alive. Spore-forming probiotics, on the other hand, are capable of withstanding threats such as light, heat and acid. They don’t require refrigeration (most of the time), and since they feature an extra layer of protection that stays intact during their journey, they can usually reach the lower intestine alive, where they’re able to grow and populate.

Perhaps the most interesting aspect of spore-forming bacteria is how they affect the body once they are able to effectively colonize the lower intestine. While traditional probiotics help to bolster the amount of beneficial bacteria in the gut and keep “bad” bacteria under control, they are incapable of forming new, additional spores and effectively replace their own genetic material.

How the Human Microbiome Has Changed Over Centuries

One of the most important things to understand when it comes to SBOs and lactic acid-based probiotics is how the human microbiome has evolved over centuries of human development. Diet has had a tremendous impact as it evolved quickly.

Before the existence of agricultural societies, the majority of food eaten by humans was wild in nature — foraged berries, wild-growing plants, root vegetables and pretty much anything else that grows close to or underneath the earth’s surface, along with meat. Food was always eaten “as is” and was never washed the way it often is today.

A great deal of soil-based bacteria made it onto both the food that was eaten and the hands of those who were eating it. This naturally led to SBOs getting ingested along with whatever food was being eaten. The SBOs would eventually travel to the digestive tract wherein they would work to colonize the gut. Because the process was bound to be repeated every day, humans never experienced a shortage of interaction with soil-based organisms — the gut had what it needed to effectively fight against harmful pathogens.

It’s also worth noting that pre-agricultural soil was much richer in various microbes than modern soil in which our crops are grown. While the soil of the pre-industrial past may have been loaded with essential nutrients (zinc and calcium, as examples) and a diverse range of different microbes, the use of pesticides, herbicides and other chemicals in today’s agricultural society has changed soil characteristics. Many SBOs that might be found naturally in certain environments centuries ago, unfortunately, would be difficult if not impossible to encounter in today’s world.

From SBOs to Lactic Acid-based Organisms

As society progressed over the decades and centuries, so too did the ways in which food is grown and consumed. Rarely are people foraging for their meals today, and the sanitization of agricultural practices has led to a veritable war against bacteria, which is often viewed as being harmful to our health instead of beneficial. It should come as no surprise, then, that the gut microbiome has changed in many different ways since the switch to an agricultural society — primarily in the types of organisms that populate the gut in modern humans.

While soil-based organisms once held strong footing in the gut, they no longer occur naturally in humans. Instead, gut bacteria is comprised largely of lactic acid-based organisms. It is for this reason that many of the most common and popular probiotics available are formulated with lactic acid-based strains of bacteria, which help repopulate the lower intestine when certain factors have created an imbalance between “good” and “bad” bacteria.

One of the newest forms of probiotics available today are those that contain spore-forming cultures, soil-based organisms that don’t typically occur naturally in the human gut. Spore-forming cultures are thought to “seed” the gut with beneficial bacteria that is not only different from lactic acid-based organisms but are more adaptable and able to better withstand the highly acidic environment of the stomach.

Choosing a Probiotic Supplement

For those who deal with uncomfortable digestive issues, finding a solution can take a bit of trial and error. In some cases, a probiotic supplement may be exactly what it takes to restore order to the microbiome and protect against harmful bacteria. Often, choosing the “right” probiotic can be an exercise in frustration, especially when considering just how many different types of products are available on the market. .

Here are a four guideposts to keep in mind if you’re looking to try a probiotic supplement:

1. Choose Single-strain Probiotics It’s common to see probiotics supplements that combine numerous different strains into one dosage form. While this may seem like good practice at face value, it typically ends up causing more harm than good — in some cases, different strains may fight and kill one another for dominance. Instead, choose single-strain probiotics and experiment with different options until you find a supplement that works well for you.


2. Don’t Over-focus on CFUs Colony forming units (CFUs) are often listed as a number on packaging for probiotics supplements, sometimes reaching into the tens of billions. In this case, however, “more” doesn’t necessarily mean “better.” Go with a supplement that contains approximately 8 million CFUs of live active cultures; 8 billion CFUs is the top end of what the body is usually able to process effectively – and you won’t be wasting your money on CFUs that your body can’t use.


3. Try Lactic Acid-based Probiotics Before Considering Spore-forming Cultures SBO probiotics are usually most effective in those who see little to no benefits from taking lactic acid-based supplements — a very small population of people. Before trying a supplement that contains spore-forming cultures, go with a lactic acid-based bacteria strain first to ensure it doesn’t get the job done on its own.


Spore-forming cultures and probiotics that make use of them aren’t right for everyone, but they represent a unique new approach to restoring balance to the gut microbiome.
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