Hello,

I need your support and suggestions. When I autoclave broth media and put them in my anaerobic cabinet to pre-reduce, the pH will drop of 0.5-1.0 (depending on the medium composition and its buffering capacity) due to the CO2 present in the gas mix that is dissolving and acidifying the media. What I've been doing so far is autoclave, then adjust the pH (as autoclaving can alter the pH too) in sterile conditions, considering the pH drop after pre-reduction with the CO2-containing gas mix. However, adjusting the pH in sterile conditions is not optimal as I need to open the bottle and take aliquots with the risk of contaminating my media. So the ideal would be to correct the pH before autoclaving, but I will need to take into consideration pH alteration by the sterilization cycle and pre-reduction.

Does any of you have any suggestion or tips to address this point?

Thank you very much!