The Use of Emulsification Technologies to Enhance Rapeseed Oil Consumption During Industrial Streptomyces rimosus Fed-batch Fermentations

Phase inversion temperature (PIT) and self-emulsification (SE) technologies were used to produce novel forms of oil feed for fed-batch fermentations. These novel forms were supplied with the aim of improving both oil utilisation and product titre whilst reducing fermentation broth viscosity. The study involved industrial Streptomyces rimosus fermentations fed with rapeseed oil (RSO) for the production of oxytetracycline. In all cases, oil utilisation increased when compared to the control process. Additionally, a very significant decrease (∼50%) in the final concentration of residual oil was also achieved when either the PIT or self-emulsifying technologies were used. Further, a significant decrease (∼75%) in the culture broth viscosity was also measured when using the self-emulsifying method. It was concluded that the measurable increase in the utilization of oil was due to the formation of smaller and more stable oil droplets when using such technologies and/or the lower broth viscosity, which increased the mass transfer from the complex fermentation medium to the cells. In all cases, the final oxytetracycline concentration and time of attenuation was not significantly different for any of the fermentation processes.