Shellab BACTRONEZ - Manual (Page 22)

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OPERATION
T HEORY OF O PERATION AND M AJOR C OMPONENT F UNCTIONS
Achieving Anaerobic Conditions
No
Oxygen
Hydrogen
Positive
Pressure Active
Catalyst
Figure 6: Atmosphere Control Measures
The BACTRONEZ workstation is designed to establish and maintain a strict anaerobic environment
suitable for the cultivation of clinical anaerobic bacteria. This is achieved through injections of an
anaerobic mixed gas (AMG) with a 5% hydrogen concentration, and a subsequent catalytic reaction
between the hydrogen, free oxygen in the air, and the activated palladium of the workstation’s
catalyst scrubber. This results in the oxygen being captured in the formation of water vapor.
A palladium catalyst must be kept clean and active by baking the catalyst cartridge at 200°C after
each 24 hours of usage.
A mild chamber overpressure is maintained using a workspace pressure switch sensor, AMG, and
a gas injection solenoid to help prevent infiltration by outside atmosphere.
The presence of oxygen in the workstation can be detected through the use of color-changing
Oxoid brand indicator strips. Microbiological controls such as, Clostridium novyi or Pseudomonas
aeruginosa, may also be used to indicate anaerobic or aerobic conditions. Use of an activated
charcoal scrubber in the chamber can help absorb volatile fatty acids and hydrogen sulfides
generated by cultivation processes or applications.
Condensation Management
Sample media evaporation from petri dishes and water vapor from the oxygen-capturing catalytic
reaction is trapped on the cold plate of a Peltier-effect condensate chiller located behind catalyst
cartridge. Condensed moisture is then channeled into a drain tube that empties into a receptacle
placed in the workspace chamber by the end-user. The receptacle must be drained regularly. The
Peltier condensate chiller eliminates the need to use chemical desiccants to control humidity levels
inside the chamber, which can retain condensate and dry out culture media.