Bacillus thuringiensis (Bt) is a naturally occurring bacterium found in soil and plants. It produces proteins that are toxic to certain insects, making it a valuable tool in agriculture for pest control. Farmers often use Bt as a biological pesticide to protect crops without harming beneficial insects. The bacterium is safe for humans and animals, as its toxins specifically target the digestive systems of certain pests, such as caterpillars and beetles. Bacillus thuringiensis is also used in genetically modified crops, which are engineered to express Bt proteins, providing built-in protection against pests.