For example, Clostridium perfringens and E. coli have been found to produce beta-glucuronidase, which releases free bilirubin from the bilirubin diglucuronide, the free bilirubin then precipitates with free ionized calcium ion to form calcium bilirubinate, a major component of pigment gallstones; the lipopolysaccharides produced from Gram-negative bacteria, such as Escherichia sp., Klebsiella sp., and Pseudomonas sp., can stimulate mucin secretion from dog gallbladder epithelium, which functions as an integrating factor to coagulate amorphous material into gallstones [8, 36]. This evidence concerns the gene GUSB and gallstones.