The application of novel emulsification technologies in oxytetracycline fermentations by Streptomyces rimosus

The application of novel emulsification technologies was investigated in order to improve the utilisation of oil, the production of oxytetracycline and the viscosity during industrial and non-industrial Streptomyces rimosus fermentations. Emulsifiers (Mergital Q3V® and Agnique RSO 10®) mixed with rapeseed oil were fed to industrial S. rimosus fermentations. In addition, the Phase Inversion Temperature technology (PIT rapeseed and sunflower oil emulsions) was applied on both industrial and non-industrial S. rimosus fermentations. Similarly, the Self-Emulsifying technology was used for the production of a rapeseed oil feed (Agnique RSO 3®) which contained a hydrophilic group and was fed to S. rimosus industrial and non-industrial fermentations. Increased oil utilisation was recorded in the above processes. A very significant decrease (55-65%) in the final concentration of residual oil was achieved when PIT and self-emulsifying technologies were used. A significant decrease (50-75%) in the viscosity was also observed in the self-emulsifying process. It was concluded that the increase in the utilisation of oil was due to the smaller and stable oil droplet size offered by such technologies and/or the lower viscosity which increased the mass transfer from the complex fermentation medium to the cells. The final antibiotic (oxytetracycline) concentration did not significantly increase in any of the industrial and non-industrial fermentations. However, the microorganisms was able to produce oxytetracycline after oil feed termination when oil emulsions were used to contrast to normal rapeseed oil where no production was observed. Morphological analysis of the dispersed mycelia was carried out providing information on the length and number of tips of the free mycelia. When oil was utilised at higher rates, the microorganisms showed higher metabolic activity which led to longer filaments. This was probably due to better carbon availability increasing production rate of elongation precursors inside the mycelia.EThOS - Electronic Theses Online ServiceGBUnited Kingdo