Thank you so much for your time and advice regarding my research! Just a quick side note, Im not sure if this discussion widget allows you to make comments without signing in, so I have copied and pasted your comment as well as my response into the widget that is at the top of the page (it displays a previous judge’s question as well).
My decision to use Sodium Hydroxide in the collection apparatus was backed by research published by Mark Gomelsky. As the bacteria ferment the lignocellulosic material or LCM, the bacteria not only produce hydrogen at a high percentage (93%), but also produce small amounts of carbon dioxide (6%) (as was found through Gas Chromatography done by Dr. Gomelsky’s team). When implemented in a large scale setting, this carbon dioxide production would add up, and its production would be magnified. To solve this problem, sodium hydroxide was used in the apparatus instead of water. While being displaced by the gas accumulated at the top of the tube, sodium hydroxide absorbs any excess carbon dioxide, essentially leaving behind pure hydrogen and making the process even more environmentally favorable.
The muconic acid tests were run by using the ”spent” media, already enriched with organic acids from one type of fermentation process, to boost the other. In the case of my study, I used “spent” media from P. putida (which produced muconic acid) to fuel hydrogen production. This transfer of media, enriched with organics, not only supplies the “hydrogen bacteria“ with more organic substrate, but also acts as a way to remove inhibitory buildup from the muconic acid producing bacteria. The muconic acid was detected using HPLC from a local environmental lab, but was never actually extracted. PHB was used in the study as an example of the vast range of metabolites that could be produced due to genetic engineering of the bacteria. In the actual study, the production of hydrogen and muconic acid (as a value added product), was targeted through a genetic engineering approach that targeted specific hydrogen and muconic acid related genes (in their respective bacteria). However, the production of other useful metabolites (PHB) probably also occurred as part of their innate pathways. Both hydrogen production and muconic acid production were part of prior actual lab experiments.
The ideas and research for this project happened in the beginning of the year, around February, but actual experimentation started in the summer and ended towards the end of fall, so approximately 1.5 semesters. Once again, thank you for your time in reviewing my work, and I hope I could answer all of your questions!
Ryu, M.-H., Hull, N. C., & Gomelsky, M. (2014, February 26). Metabolic engineering of Rhodobacter sphaeroides for improved hydrogen production. Retrieved from https://www.sciencedirect.com/science/article/pii/S0360319914003814