Studies on Antibacterial Factors in Mammalian Tissues and Fluids

Abstract

The rabbit serum and human serum bactericidin systems for Bacillus subtilis were studied for participating cofactors. Both calcium ions and bicarbonate ions are required for activity of the human bactericidin, whereas only bicarbonate ions are required for the rabbit system. Bicarbonate ions must be present in the reaction mixture since cells grown on bicarbonate and then washed free of bicarbonate are not sensitive to the rabbit serum bactericidin. B. subtilis in the presence of sodium bicarbonate is not sensitive to egg white lysozyme which tends to rule out lysozyme as a major component of the serum systems. Antisera prepared against B. subtilis in rabbits neither influences the serum bactericidin levels nor alters the sensitivity of B. subtilis to the rabbit bactericidin.