Geobacillus 7349 – A new potential biosurfactant producing microorganism

Sammanfattning: The main aim of this master project is to find out whether strain Geobacillus 7349 can produce biosurfactant during their growth by extraction and characterization of the product. The other goal is to optimize the cultivation condition of the strain. This work presents an evaluation of batch and fed-batch cultivation techniques for production of Geobacillus 7349 in shake flask, using DRM medium. The growth condition of the strain was monitored by cell density (OD) measurement, cell dry weight measurement, along with glucose consumption characterized by HPAEC-PAD. Batch cultivation results in a high cell density (OD600 ≥ 5) after around 14 hours of cultivation and a high concentration of biosurfactant being produced. To extract the biosurfactant from the culture broth, liquid-liquid extraction is an effective method. In both batch and fed-batch cultivations, the production of biosurfactant was detectable in both exponential and stationary phase, by the usage of high-performance liquid chromatography (HPLC), which means the cells were active in producing biosurfactant during these phases. And the fed-batch cultivation supplemented with fresh feed solution containing MgCl2, NH4Cl, and NaCl can increase the cell density threshold and prolong the lifespan of cell generation. To conclude, the project demonstrates the production of biosurfactant from strain Geobacillus 7349 by fermentation and the importance of the process design and nutrient source for bacterial growth. Hopefully, these findings can be used to scale up the fermentation process of Geobacillus 7349 from lab scale to trial scale, in order to have a more substantial biosurfactant production.