Bacillus Subtilis HU58 is a friendly bacterial spore that was discovered in a healthy human gut at the University of London. HU58 is an incredibly rugged spore that can withstand extreme pH levels, high temperatures, dehydration, antibiotics, pressure, radiation, and even the harsh environment of the digestive tract. It can also produce over 12 targeted antibiotics of its own, which makes it particularly effective at balancing gut flora.