Cell rupture by high-speed homogenization and by cold plasma to produce microbial lipids

This study aimed to optimize two cell disruption methods, i.e., high-speed homogenization (Ultra-turrax) and cold plasma, to efficiently recover microbial lipids from Rhodotorula mucilaginosa CCT 7668. A previously optimized medium composed of agro-industrial byproducts (70 g/L sugarcane molasses and 3.4 g/L corn steep liquor) was used for producing lipids at 25 °C, 180 rpm for 144 h. Different pretreatments of biomass (wet, dry, and/or frozen) were evaluated; 7.0% of lipid content and 0.50 g/L total lipids resulted from the use of dry and frozen biomass. An experimental design methodology was applied to study the following variables: biomass:solvent ratio (0.3:100–1.2:100), operation time (0.6–7.4 min) and rotation speed (9280–22,720 rpm), when high-speed homogenization was used. Lipid contents ranged from 9.6 to 35.2% while total lipids ranged from 0.80 to 2.96 g/L. Regarding the cold plasma technology, biomass (0.5–0.7 g), operation time (20–40 min) and power (8–14 W) were evaluated. Lipid contents ranged from 20.6 to 34.9% while total lipids ranged from 1.81 to 3.06 g/L. Therefore, this study defined optimal conditions to efficiently produce microbial lipids with low toxicity, which represent potential sources that may be applied to food and pharmaceutical industries.