gaspak

GasPak is a brand-name term used for a family of anaerobic culture systems used in microbiology to create oxygen-free or reduced-oxygen environments for growing certain organisms. The most common configuration is the GasPak anaerobic jar, a sealable container paired with an indicator strip and one or more gas-generation sachets. The sachets release gases, and, in the presence of a palladium catalyst, residual oxygen is removed, producing an anaerobic atmosphere. Many kits also include a carbon dioxide-generating component to enrich the atmosphere for capnophilic organisms. An oxygen indicator, such as resazurin or methylene blue, changes color to show when oxygen has been removed, signaling that anaerobic conditions have been achieved.

Operation: Cultures are placed in the jar, the GasPak sachet and indicator are added, and the jar is sealed. A small amount of water is added to activate the sachet. Gas generation and catalytic removal of oxygen typically create anaerobic conditions within several hours, which are maintained as long as the jar remains sealed. The system is widely used for growing obligate anaerobes like Bacteroides and Clostridium, as well as some microaerophilic or CO2-requiring organisms.

History and context: GasPak systems were developed in the mid-20th century and became standard in many clinical and research laboratories. They offer a low-cost, compact alternative to anaerobic chambers, though they require careful handling and proper sealing to maintain conditions.

Limitations: They are less suitable for strict anaerobes requiring extremely low redox potential, and any leakage or improper activation can compromise conditions. They are not ideal for long-term, large-volume cultures or for organisms needing precise atmospheric control.