McIntosh and Fildes' anaerobic jar is an instrument used in the production of an anaerobic environment. This method of ''anaerobiosis'' as others is used to culture bacteria which die or fail to grow in presence of oxygen (''

anaerobes An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenate ...

''). It was originally introduced by James McIntosh, Paul Fildes and William Bulloch in 1916. McIntosh and Fildes, after whom the device has been named, published an improved version in 1921.

Construction

The jar, about 20″×12.5″ is made up of a metal. Its parts are as follows: #The body made up of

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

(airtight) #The lid, also metal can be placed in an airtight fashion #A

screw A screw and a bolt (see '' Differentiation between bolt and screw'' below) are similar types of fastener typically made of metal and characterized by a helical ridge, called a ''male thread'' (external thread). Screws and bolts are used to fa ...

going through a curved metal strip to secure and hold the lid in place #A

thermometer A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...

to measuring the internal temperature #A

pressure gauge Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressur ...

to measuring the internal pressure (or a side tube is attached to a manometer) # Another side tube for evacuation and introduction of

gases Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

(to a gas cylinder or a

vacuum pump A vacuum pump is a device that draws gas molecules from a sealed volume in order to leave behind a partial vacuum. The job of a vacuum pump is to generate a relative vacuum within a capacity. The first vacuum pump was invented in 1650 by Otto v ...

) #A wire cage hanging from the lid to hold a

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

that makes hydrogen react to oxygen without the need of any

ignition Ignition may refer to: Science and technology * Firelighting, the human act of creating a fire for warmth, cooking and other uses * Combustion, an exothermic chemical reaction between a fuel and an oxidant * Fusion ignition, the point at which a ...

source

Method of use

*First: #The culture: The

culture media A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Different ...

are placed inside the jar, stacked up one on the other, and #

Indicator Indicator may refer to: Biology * Environmental indicator of environmental health (pressures, conditions and responses) * Ecological indicator of ecosystem health (ecological processes) * Health indicator, which is used to describe the health o ...

system: ''

Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common encapsulated, gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, ''P. aerugi ...

'', inoculated on to a nutrient agar plate is kept inside the jar along with the other plates. This bacteria need oxygen to grow (''

aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cellu ...

''). A growth free culture plate at the end of the process indicates a successful anaerobiosis. However, ''P. aeruginosa'' possesses a denitrification pathway. If nitrate is present in the media, ''P. aeruginosa'' may still grow under anaerobic conditions. *Second: ⁶/₇^ths of the air inside is pumped out and replaced with either unmixed Hydrogen or as a 10%CO₂+90%H₂ mixture. The catalyst (

Palladium Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself na ...

) acts and the oxygen is used up in forming

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

with the hydrogen. The

manometer Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressur ...

registers this as a fall in the internal pressure of the jar. *Third: Hydrogen is pumped in to fill up the jar so that the pressure inside equals

atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 7 ...

. The jar is now incubated at desired temperature settings.

References

{{Clinical microbiology techniques Laboratory equipment Microbiology terms Microbiology equipment