Abstract: The main biological characteristics of six Bacillus strains isolated were studied,including the activity of enzyme-producing,the endurance to NaCl,bile salt and artificial gastric juice as well as artificial intestinal fluid and the sensitivity to antibiotics. The results showed that,Bacillus subtilis strain 1,B.coagulans and B.cereus had the capability of producing high yield of protease and amylase. Two strains of B.subtilis and B.coagulans showed well resistance to high concentration of NaCl. B.subtilis strain 2,B.coagulans and B.natto as well as B.cereus had relatively strong tolerance for bovine bile salt. Except B.licheniformis,the other five strains of Bacillus could resist the artificial gastric and intestinal fluid well. Six strains of Bacillus were sensitive to common forage antibiotics. These results showed that B.subtilis 1,B.coagulans and B.cereus were excellent probiotics.

Key words: Bacillus; biological characteristics; enzyme; artificial gastric juice; artificial intestinal fluid; drug sensitivity