Obligate anaerobic bacteria require an oxygen-free environment for growth, which can be achieved through methods like evacuation and replacement or chemical absorption. Common systems include the automated Anoxomat and the Gaspak system, both designed to create anaerobiosis efficiently. Other methods such as Genbag and Genbox facilitate anaerobic conditions for sample testing, while indicators like reduced methylene blue confirm the success of these methods.

1. DR.K.AARATHI

2.  Obligate anaerobic bacteria can grow only in the absence of
oxygen.
 Growth of such bacteria, anaerobic environment is needed.
 Methods used to create anaerobiosis are-
 Evacuation and Replacement
 This involves evacuation of the air from jar and replacement
with inert gas like hydrogen followed by removal of the
residual oxygen by use of a catalyst.
 It is carried out either by:™
™

3.  Manual method by
using McIntosh and
Filde’s anaerobic jar .
 Most popular method
for creating anaerobiosis
in the past,not using
presently.
 ™
™

4.  Automated system
(Anoxomat): It
automatically
 Evacuates air and replaces
by hydrogen gas from a
 cylinder.
 „
„
The catalyst used to
combust residual oxygen
is a sachet containing
aluminum pellets coated
with palladium.

5.  Absorption of Oxygen by Chemical
Methods-
 GasPak system
 Most commonly used method for
anaerobiosis, especially for laboratories
with less sample load.
 ™
™
Oxygen is removed by chemical
reactions.
 ™
™
It uses a sachet containing sodium
bicarbonate and sodium borohydride
which react chemically in presence
 of water, to produce hydrogen and CO2
gas.
 ™
™
The traces of oxygen is removed by
using the same catalyst used for
Anoxomat placed below the jar lid .
™
™

6.  GENbag
 Place the plates in the airtight bag.
 Open the protective aluminium foil
pouch.
 Remove the generator and
immediately place it into the bag.
 Do not add water or a catalyst.
 Place the clip seal on the bag,
immediately seal the pouch and
incubate.
 GENbag enables the incubation of 1
or to 2 plates, identification or
susceptibility testing strips, 1
microtitration plate.
 Bacterial growth can be observed
without opening, through the
transparent bag.
.

7.  GENbox
 Place the plates in the jar. For GENbox
 anaer, add the anaerobic indicator stick.
 Open the protective aluminium foil
pouch.
 Remove the generator and immediately
place 1 generator for GENbox jar 2.5L
or 3 for GENbox 7.0 L.
 Do not add water or a catalyst.
 Immediately seal the jar and incubate.
 Rectangular GENbox jars are compact
and easily stackable.
 The transparent cover and container
enable direct observation of cultures.

8.  Anaerobic Glove Box
and Anaerobic Work
Station:
 These systems provide
facility for easy
processing, incubation
and examination of the
specimens without
exposure to oxygen .
 ANAEROBIC GLOVE BOX

9.  Indicator of anaerobiosis: The effectiveness of
 anaerobiosis can be checked by:
 „
„Reduced methylene blue remains colorless in anaerobic
conditions, but turns blue on exposure to oxygen.
 „
„Pseudomonas : Absence of its growth indicates that complete
anaerobiosis has been achieved.It is used as biological indicator.