SOP For Growth Promotion Test of Biological Indicators


SOP for growth promotion test of biological indicators is described in this post which you can follow in the section of microbiological lab.


This procedure has been established for the growth promotion test of biological indicators.


This procedure is applicable to microbiology lab.




Quality Control Manager.            


For qualification of biological indicator i.e. (Geobacillus Stearothermophilus) take 10ml of nutrient broth and inoculate the spores from any one of the ampoule of indicator randomly followed by incubation period of 37ºC for 48 hrs. 

Transfer a loopful of the culture from pre-incubated culture in two Petri plates separately containing nutrient agar followed by incubation of  one Petri plate at 30ºC-35ºC and the other at 55ºC-60ºC for 24 hours. 

Culture or biological indicator will qualify if incubation at 55ºC to 60ºC shows microbial growth while no growth observed at 30ºC-35ºC incubation period.

Total Viable Count of Biological Indicator 

Select four different ampoules of biological indicator randomly by composite sampling from each lot.

Transfer the spores in 5ml of sterile purified water in a screw capped test tube and vortex for 4-7mints then add another 5ml of purified water and vortex again

 then from this suspension take 1ml of the vortex culture in a screw capped sterilized test tube having 9ml of sterile purified water and then place this solution containing culture suspension in a preheated water bath at 95ºC – 100ºC for 15±1 minutes. followed by rapidly moving in ice bath at (0ºC – 4ºC). after providing heat shock vortex the tube containing culture atleast for 10seconds and perform serial dilution to yield atleast 30-300 colonies. 

For each serial dilution prepare a separate plate of media and pour 1ml of the solution of dilution followed by 20-25ml of the nutrient agar in each plate and allow solidifying and the set the plate for incubation at a temperature of 

55º – 60ºC at the end  or completion of incubation period count the number of CFU. take the average number of CFU and the multiply by dilution factor to calculate the actual original count per plate. 

Record the activity in respective logbooks

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