Bacilli

Bacilli are a type of bacteria that are rod-shaped. They are part of the Bacillaceae family, which includes both harmful and beneficial species. Some bacilli are able to form endospores, which can survive in harsh conditions for long periods of time.

Characteristics

Bacilli are typically aerobic organisms, but there are exceptions. For example, the genus Clostridium is anaerobic. Bacilli are also usually Gram-positive, but again, there are exceptions.

Bacilli can be arranged in several ways based on their cellular arrangement: in chains (streptobacilli), in clusters (staphylobacilli), or individually (monobacilli).

Pathogenic Bacilli

Several species of bacilli are known to cause disease in humans. These include:

• Bacillus anthracis, which causes anthrax
• Bacillus cereus, which causes food poisoning
• Listeria monocytogenes, which causes listeriosis
• Clostridium perfringens, which causes gas gangrene
• Clostridium tetani, which causes tetanus

Beneficial Bacilli

Not all bacilli are harmful. Some species are used beneficially in medical, industrial, and agricultural contexts. For example:

• Bacillus subtilis is used as a model organism in laboratory research.
• Bacillus thuringiensis produces a toxin that is used as a pesticide.
• Bacillus clausii is used as a probiotic in the treatment of gastrointestinal disorders.

See Also

• Bacteria
• Gram-positive bacteria
• Endospore
• Aerobic organism
• Anaerobic organism