Physiology of the polyextremophile Natranaerobaculum magadiense

Concrete is a strong, durable and cheap material. Its main problem is cracking, inducing to major problems like sulphate and chloride attacks, carbonation and decalcification. Repairing concrete can be very costly. The solution is the Self Healing Concrete. A sustainable, reliable, economical, in long term, and stable concept. Based on an aerobic spore-forming bacteria introduced in concrete and whenever there was a crack and water came in, the bacteria would start precipitating CaCO3. Concrete can be found also in oil wells. Due to high temperatures and pressures, suffers a lot of stresses and tensions. In Aarhus University, researchers decided to apply the Self Healing Cement in this anaerobic environment. A proper bacteria needed to be found to handle such conditions. Natranaerobaculum magadiense (N. magadiense) was the bacteria to be studied. The project is centred on the precipitation of CaCO3 induced by N. magadiense. The main goal of this work was to study the physiology of N. magadiense at different conditions. It was investigated its behaviour in terms of extreme conditions, since it is a polyextremophile. The project tests involved a reduction of carbonate (HCO –3 ) from the optimum media, that conflict with microbial CaCO3 precipitation. N. magadiense’s behaviour when the pH was changed. A carbon source replacement to measure the CO2=CO 2–3 production and extreme conditions were applied and the results were evaluated. We proved that N. magadiense cannot grow without carbonates. It was not found a good replacement carbon source. [HCO –3 ] cannot be reduced a lot, and [NaCl] cannot be a replacement compound, since [Cl– ] inhibited the cells, and it is not recommended to change the pH. The iron reduction process is more noticeable at lower temperatures and the fermentative process is at higher temperatures. In conclusion, N. magadiense is a good candidate to be used in the oil industry but more research is needed to move to its application