B. pseudomallei and B. mallei

Burkholderia pseudomallei is a Gram-negative, bipolar, aerobic, motile rod-shaped bacterium. It is a soil-dwelling bacterium endemic in tropical and subtropical regions worldwide, particularly in Thailand and northern Australia. It infects humans and animals and causes the disease melioidosis. It is also capable of infecting plants. B. pseudomallei measures 2-5 μm in length and 0.4-0.8 μm in diameter and is capable of self-propulsion using flagella. The bacteria can grow in a number of artificial nutrient environments, especially betaine- and arginine-containing ones. Burkholderia mallei is a Gram-negative, bipolar, aerobic bacterium, a human and animal pathogen of genus Burkholderia causing glanders. It is closely related to B. pseudomallei, and by multilocus sequence typing, it is a subspecies of B. pseudomallei. B. mallei evolves from B. pseudomallei by selective reduction and deletions from the B. pseudomallei genome. Unlike B. pseudomallei and other genus members, B. mallei is nonmotile; its shape is coccobacillary measuring some 1.5-3.0 μm in length and 0.5-1.0 μm in diameter with rounded ends.