Evaluation of cell disruption methods in the oleaginous yeasts Yarrowia lipolytica QU21 and Meyerozyma guilliermondii BI281A for microbial oil extraction

Abstract

The interest for oleaginous yeasts has grown significantly in the last three decades, mainly due to their potential use as a renewable source of microbial oil or single cell oils (SCOs). However, the methodologies for cell disruption to obtain the microbial oil are considered critical and determinant for a large-scale production.Therefore, this work aimed to evaluate different methods for cell wall disruption for the lipid extraction of Yarrowia lipolytica QU21 and Meyerozyma guilliermondii BI281A.The two strains were separately cultivated in 5 L batch fermenters for 120 hours, at 26 ºC and 400 rpm. Three different lipid extraction processes using Turrax homogenizer, Ultrasonicator and Braun homogenizer combined with bead milling were applied in wet, oven-dried, and freeze-dried biomass of both strains. The treatment with the highest percentage of disrupted cells and highest oil yield was the ultrasonication of oven-dried biomass (37-40% lipid content for both strains). The fact that our results point to one best extraction strategy for two different yeast strains, belonging to different species, is a great news towards the development of a unified technique that could be applied at industrial plants.

Nutritional and Medicinal Properties of Microbial Oil

“…The reality of using SCOs is far from being achieved, due to the high cost of their recovery from biomass. The costs can be lowered by the usage of a waste carbon source in the culture medium and by a reduction in the operational costs of SCO extraction, which may be accomplished by mechanical methods, chemical and enzymatic methods, or a combination of them [46,47]. Based on the current literature, there is no extraction method that is 100% effective in yielding oils derived from microorganisms.…”

“…These methods can help to make the lipid structure more accessible to the solvents, thereby reducing the biggest limitation of the process-the diffusion of the solvent into the raw material [54]. Timotheo et al [47] evaluated liquid nitrogen pre-treated biomass and maceration, followed by ultrasonication extraction, as the treatment with the highest percentage of disrupted cells and the highest oil yield of Y. lipolytica QU21 and Meyerozyma guilliermondii BI281A. Some investigations point out that the lipid yield decreased with increasing pressure, and low pressure (200 MPa) collapsed the cells, while high pressure (400 MPa) created protrusions on the cell wall and the cell fragments spread into the environment [55].…”