McIntosh and Fildes’ Anaerobic Jar – Principle, Parts, Procedure

What is McIntosh and Fildes’ Anaerobic Jar?

Designed to provide an oxygen-free environment required for growing bacteria unable of surviving in the presence of oxygen, McIntosh and Fildes’ anaerobic jar is a specialist piece of laboratory equipment. Usually built from strong metal or glass, the jar has a firmly closing lid and has input and exit tubes to let air be removed using a vacuum pump and then gases, including hydrogen, be introduced. A palladium catalyst within the jar helps any leftover oxygen to react with the hydrogen gas, producing water and thereby lowering the oxygen concentration even further. Originally designed by McIntosh and Fildes in the early 20th century, this device has been crucial in anaerobic bacteriology as it offers a consistent means of cultivating obligatory anaerobes. Although the technique has historical significance and efficiency, its progressive replacement by more modern and user-friendly methods such as the GasPak system in modern laboratories results from its need for specialist equipment and cautious handling notwithstanding its historical relevance.

Principle of McIntosh and Fildes’ Anaerobic Jar

Based on replacement and evacuation, McIntosh and Fildes anaerobic jar operates whereby the air within the chamber is expelled and replaced with a combination of gas (with 5% CO2, 10% H2 and 85% N2).

A little bit of oxygen will remain as it is practically difficult to completely remove all the air. Palladium or Spongy platinum catalyst helps the remaining oxygen be turned into water. Acting as a catalyst, the substance causes gradual synthesis of oxygen and hydrogen to produce water. One can show (combination from NaOH methyleneblue, along with glucose) reduced methylene blue. When it is inaerobically handled, it becomes colorless; yet, it becomes blue when it comes into touch with oxygen.

Components of the Jar

Designed to provide an oxygen-free environment for growing anaerobic bacteria, the McIntosh and Fildes’ anaerobic jar Its main parts are:

• Main Body- Usually standing at 20 cm in height and 12.5 cm in diameter, built from strong glass or metal.
• Lid- a tightly fitting metal lid clasped firmly to provide a perfect seal. Equipped with two tap-equipped tubes:
  • Gas Inlet Tap: For Jar introduction of gases.
  • Vacuum Outlet Tap: For air evacuation from the jar, use a vacuum outlet tap.
  • Has two electrical contacts under the lid linked to a catalyst holder.
• Catalysts- Sturdy wires attached to the electrical connections hang a capsule filled with alumina pellets covered with palladium (palladinized alumina) behind the lid. By helping leftover oxygen and hydrogen to create water, the catalyst removes any last oxygen from the process.

Procedure

1. Put your inoculated culture plates into the container. To aid verify the lack of oxygen, add an anaerobic indicator—such as low methylene blue.
2. Close the lid firmly to establish an airtight surroundings.
3. Shut the gas inlet tap. Connect a vacuum pump to the tap at the vacuum output. About 75% of the air from the jar should be evacuated to lower the internal pressure to maybe 100 mm Hg. Once the air is gone, close the hoover outlet tap.
4. Link a supply of hydrogen gas to the gas input tap. Add hydrogen until internal pressure of the jar recovers to atmospheric levels (760 mm Hg).
5. Usually palladium-coated alumina, the catalyst in the jar will react with any residual oxygen and hydrogen to produce water, therefore guaranteeing an oxygen-free surroundings.
6. Put the sealed jar in an incubator set at the ideal temperature for microbial development.
7. After incubation, check the anaerobic indicator to be sure the surroundings stays oxygen-free.

Uses

• Maintenance of Anaerobic Bacteria- The jar offers an oxygen-free environment necessary for the development of obligate anaerobes including species of Clostridium.
• Clinical Tests- It is used in medical laboratories to separate and identify anaerobic bacteria from clinical specimens, therefore helping to diagnose illnesses brought on by these organisms.
• Research and Development- Using the jar, researchers investigate the physiology, metabolism, and genetics of anaerobic bacteria, thereby advancing microbiology and allied sciences.
• Food and pharmaceutical industry quality control- Anaerobic pollutants in goods are found and investigated using the jar, therefore guaranteeing industry standards compliance and safety.

Advantages of McIntosh and Fildes’ Anaerobic Jar

For growing anaerobic bacteria, the McIntosh and Fildes’ anaerobic jar has many benefits:

• Effective Anaerobic Environment- The jar effectively generates an oxygen-free environment necessary for the development of obligate anaerobes by removing air and substituting hydrogen.
• Catalyst Efficiency- By means of its reaction with hydrogen to generate water, the incorporated palladium catalyst speeds the elimination of residual oxygen, therefore assuring quick development of anaerobic conditions.
• Versatility- The jar fits for several microbiological uses as it can hold several kinds of culture medium and sample quantities.
• Reusability– Built from robust materials, the jar provides laboratories with a reasonably priced option as it is meant for regular usage.
• Controlled Environment– Perfect control of internal conditions, including gas composition and pressure, made possible by the technology improves the dependability of experimental findings.

Limitations of McIntosh and Fildes’ Anaerobic Jar

Although the McIntosh and Fildes’ anaerobic jar works well for growing anaerobic bacteria, it has numerous drawbacks:

• Simple Setup and Operation– The procedure calls for a vacuum pump and exact control of gas flow as air is evacuated and hydrogen gas is used in replacement. This intricacy might make the operation time-consuming and difficult.
• Equipment Requirements– For labs with limited resources, the demand for specialized tools such a vacuum pump and hydrogen gas supply might be a drawback.
• Safety issues– Because hydrogen gas is flammable, handling it presents safety concerns; so, great adherence to safety standards is necessary to avoid mishaps.
• Inaccurate Elimination of Oxygen– Some residual oxygen might still exist even after gas replacement and evacuation, thereby influencing the development of stringent anaerobes.
• Maintenance on Catalysts– Especially in the presence of moisture or pollutants, the palladium catalyst employed to eliminate residual oxygen might become deactivated over time and needs frequent maintenance or replacement.
• Restricted Capacity– In high-throughput environments, the physical dimensions of the jar limit the number and size of culture plates that may be incubated concurrently, therefore restricting potential.
• Alternative Techniques– More contemporary and user-friendly solutions, including the GasPak system, have been created, providing more ease and less depending on specialist tools.