Enhanced valorization of industrial wastes for biodiesel feedstocks and biocatalyst by lipolytic oleaginous yeast and biosurfactant-producing bacteria

The lipolytic oleaginous yeast Yarrowia lipolytica and biosurfactant-producing bacteria Bacillus subtilis were used to improve the valorization of palm oil industrial wastes for lipids and lipases. Biosurfactant likely enhanced the performance of the yeast by modifying hydrophobic substrates and cell membrane permeability leading to an increase in substrate entry and also secretion of lipases. The secreted lipases and biosurfactant also synergistically enhanced the biodegradation of the wastes, especially the removal of hydrophobic compounds. The COD and oil removal were improved by 1.47 folds and 2.33 folds, respectively. Consequently, the yeast could grow better on the wastes and accumulate higher lipid content by 1.3-1.5 folds. The biosurfactant also positively affected saturated fatty acid contents in the yeast lipids which make them more suitable as biodiesel feedstocks with higher cetane number and better oxidative stability. This biological process not only improves the biodegradation of environmental pollution from industrial wastes but also lowers the production costs of lipids as biodiesel feedstocks and lipases as biocatalyst.