The extraction of a microbial or single cell oil, for example comprising
one or more polyunsaturated fatty acids (PUFAs), directly from microbial
cells is disclosed which avoids the need for solvents. After
fermentation, the microbial cells are pasteurised, washed and the cell
walls lysed or disrupted by a mechanical (e.g. homogenisation), physical
(boiling or drying), chemical (solvents) or enzymatic (cell wall
degrading enzymes) technique. The oil (containing the PUFA) is then
separated from the resulting cell wall debris. This is achieved by
centrifugation, which results in an oily phase (top layer) that contains
the oil which that can be separated from an aqueous phase (containing the
cell wall debris). The oil can then be extracted and if necessary the
PUFA can be purified or isolated from the oil.