Non‐sterile cultivation of Yarrowia lipolytica in fed‐batch mode for the production of lipids and biomass

Abstract A reduction in the cost of production and energy requirement is necessary for developing sustainable commercial bioprocesses. Bypassing sterilization, which is an energy and cost‐intensive part of bioprocesses could be a way to achieve this. In this study, nonsterile cultivation of Yarrowia lipolytica was done on a synthetic medium containing acetic acid as the sole carbon source using two different strategies in the fed‐batch mode. The contamination percentages throughout the process were measured using flow cytometry and complemented using brightfield microscopy. Maximum biomass and lipid yields of 0.57 (g biomass/g substrate) and 0.17 (g lipids/g substrate), respectively, and maximum biomass and lipid productivities of 0.085 and 0.023 g/L/h, respectively, were obtained in different fed‐batch strategies. Feeding at the point of stationary phase resulted in better biomass yield and productivity with less than 2% contamination till 48 h. Feeding to maintain a minimum acetic level resulted in better lipid yield and productivity with less than 2% contamination during the complete process. The results of this study demonstrate the potential for cultivating Y. lipolytica in nonsterile conditions and monitoring the contamination throughout the process using flow cytometry.