zhang22

Hello everyone, this is my first post here. I'm a graduate researcher in environmental engineering, and my project requires quite a bit of microbiological work. Unfortunately, I'm not very familiar with the associated techniques. I need to grow anaerobic metal reducing bacteria on acetate and nitrate, and currently buffer them in a bicarbonate/CO2 system. This works well, except for the fact that the CO2 wreaks havoc in my microfluidic reactors. These reactors are 3 microliters or less in volume, and one single bubble will ruin an experiment. I can sonicate and degas my media before injecting it into my reactor to make it bubble free, but that would alter the pH by the removal of CO2.

So, I'm looking into HEPES and MOPS as alternative buffers because I think they can be used without CO2, or any dissolved gases for that matter. I have HEPES and I have MOPS, but I don't know how to use them. For example, I see papers where people add 10 mM HEPES and get a pH of around 7.2-7.4, which is what I want. Do these people just add HEPES to this concentration, or do they add it and then adjust the pH? If they adjust the pH, what chemicals do they use to do this? So far I'm under the impression that I just need to add the buffers directly to the media at certain concentrations, and I'm ready to go. For example, I never need to add acid or base to my previous bicarbonate and CO2 buffered media. Any help would be very much appreciated because I'm so confused at the moment. Also, any information on MOPS concentration would be useful as well!