Total lipids are composed of neutral lipid in the form of energy
reserve bodies, as well as glyco- and phospholipids in the
structural membranes. Neutral lipids are typically the major
constituents of algal lipid-oil in aging or stressed cultures,
mainly in the form of triacylglycerols (TAGs) [22e24]. Although
both polar and neutral lipids can be converted to biodiesel
[25,26], neutral lipid is the desirable fraction since TAGs are