Porcine anthrax is caused by Bacillus, belonging to Bacillus family and aerobic Bacillus. It is a long and straight Bacillus, Gram-positive, 3 ~ 5 microns long and 1 ~ 1.5 microns wide, with capsule. Single or 3 ~ 5 thalli are connected to form short chains in sick animals. The junction of bacteria is flat, such as knife cutting or dimple, bamboo-shaped, and the free end is blunt and round. Capsules can be formed in animals, but generally they will not be formed on ordinary culture media. Under anaerobic conditions, bacteria die with the decay of the corpse, and the capsule can still remain, which is called "bacterial shadow". Spores do not form in living anthrax corpses or autopsy corpses. Once exposed to air and free oxygen, spores can be formed at a certain temperature (12 ~ 24℃). Spores are oval or round, located in the center or slightly to one end of the cell, and are not larger than the cell.

Bacillus anthracis is an aerobic bacterium. The optimum growth temperature is 30 ~ 37℃, and the optimum pH is 7.2 ~ 7.6. The nutrition requirement is not high, and it can grow in common culture medium. A long chain consisting of dozens to dozens of bacteria is formed in common culture medium. The colony is flat, gray and rough. At low magnification, the edge of the colony is curled. It grows well on blood agar plate and does not hemolyze. The virulent Bacillus anthracis can grow into mycelium or purple colony in common broth medium, the supernatant is transparent, and there are a lot of white flocculent precipitates in the tube. When gently shaken, the sediment rises and then sinks gradually, and the floc is not easy to shake when it is wound into a ball. After 2-4 days of thorn culture, gelatin can grow into a white inverted pine tree along the thorn line and liquefy from the surface down to a funnel shape along the thorn line. The virulent strain has strong liquefaction ability.

Bacillus anthracis can ferment glucose, produce acid but not gas, and not ferment arabinose, xylose and mannitol. VP test is positive, and it does not produce indole and H2S, but can reduce nitrate. When cultured in solid (agar plate) or liquid (broth) medium containing 0.05~0.5 IU penicillin G per ml, bacteria swell and adhere. When examined by microscope, Bacillus anthracis is beaded, which is often used for bacterial identification in diagnosis.

Bacillus anthracis exists in corpses, soil and water contaminated by anthrax. After the death of sick animals, anthrax exists in various organs, blood, lymphatic system, secretions and excretions. Spleen contains the most bacteria, followed by blood.

The germ cells of Bacillus anthracis have weak resistance to the outside world and die within 24 ~ 96 hours after autopsy in summer. It can survive for 6 ~ 15 hours in sunlight and 1 month in dry blood. Heating 10 ~ 15 minutes at 70℃ or boiling can cause immediate death. When the temperature is lower than 20 ~ 1 0℃ for 3 weeks, anthrax can survive in bone marrow for1week without being cut open. Common disinfectants can kill this kind of bacteria in a short time. However, after the formation of anthrax spores, the resistance is particularly strong. In the dry state, it can survive for 30 ~ 50 years or even longer under direct sunlight, 100 hour. It can survive for decades in soil, skin, hair and anthrax corpses contaminated by anthrax. If the temperature in the manure pile reaches 72 ~ 76℃, it can die within 4 days. Boiling takes more than 15 seconds, and autoclaving takes 12 1℃ for 10 ~ 15 minutes to kill. Disinfectant is 5% carbolic acid 1 ~ 3 days, 3% ~ 5% lysol 10 ~ 24 hours, and 4% tincture of iodine kills spores for 2 hours. On-site disinfection of livestock houses, utensils and feces. It can be carried out with 20% bleaching powder, or 3% ~ 5% hot sodium hydroxide solution, 2% ~ 4% formaldehyde, 0.5% peracetic acid and 0. 1% mercuric chloride solution. It takes 48 hours to soak the skin contaminated by Bacillus anthracis with 2% hydrochloric acid and 10% salt at 30℃ and 72 hours to disinfect it at 18 ~ 22℃.