After some months of inactivity I moved from protein expression and purification in Oncology to protein expression at high scale in fermenters in the area of nitrogen fixation. This is my first contribution asking for some aid.
Some of the strains , which I use are grown in aerobic conditions until ammonia depletion and the induction of the nitrogen fixation complex take place. In some strains this induction is better in anaerobiosis, so after grow in normal aireation conditions, the sole gas introduced in the fermenter is nitrogen. At the beginning of anaerobiosis the dissolved oxigen drops to zero but few minutes after it¨s observed that dissolved oxigen starts to increase to 10% as maximun depending of conditions. After the maximun it could be mantained or decrease in some cases. At the begining, I thougth that the probe was bad calibrated, but I check good calibration in some of posterior processes and this release continues. Moreover, after harvesting I fill the fermenter with water and passing nitrogen, the dissolved oxigen is zero. I have search in publications about this phenomenon and few information in this field has been published. If it´s difficult find well described fermentation procedures, in anaerobiosis it seems impossible. Does anybody have any explanation for this process?
In any case, thanks for your time. Cheers
protolderMember Since 25 Aug 2010
Offline Last Active May 07 2013 04:06 AM
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My research interests
proteins in general, expression purification assay scaling up