They are produced by oleaginous microorganisms, which is the term for those bacteria, molds, algae and yeast, which can accumulate 20% to 80% lipids of their biomass.
The most important source is some species of yeast, that are able to convert food into triglycerides and accumulate the produced lipids when fed carbohydrates.
[3] The microbial production of SCO can be conducted by submerged (SmF) or solid state fermentation (SSF).
The cultivation of M. alpina in a stirred tank reactor resulted in an increase of lipid accumulated in the cells compared to shaking flasks.
The cell are disintegrated by the impact of grinding beads and biomass as well as by compaction and shearing actions and the resulting energy transfer.
[8] Cell disruption by bead milling is simple, effective, and suitable for a wide range of microorganisms.
Ultrasound using frequencies around 25 kHz is another liquid-shear method which is frequently used in industries and found to be suitable for cell disruption.
The sample is dried, ground to a fine powder and placed on a porous thimble inside the extraction chamber.
The solvent is pumped into the extraction cell and remains a certain time, usually 5–10 min, under elevated pressure (10–20 MPa).
In supercritical state, substances have highly desirable properties making them suitable for extractions: they can penetrate into and effuse through solids like a gas, but dissolve lipids or any other analyte like a fluid.