Digestion and bioconversion of microalgal galactolipids by direct action of lipolytic enzymes on Chlamydomonas reinhardtii biomass

Microalgae, like Chlamydomonas reinhardtii, are rich in polyunsaturated fatty acids (PUFAs) bound to galactolipids. Their bioaccessibility to digestive enzymes in whole cells was tested using guinea pig pancreatic lipase-related protein 2 (GPLRP2) and Fusarium solani cutinase, showing high lipolysis levels with total galactolipid fatty acid release of 93 % with GPLRP2. These enzymes also converted galactolipid fatty acids into ethyl esters with ethanol, what could facilitate PUFA recovery from microalgal biomass. In vitro digestion studies mimicking gastric and intestinal conditions revealed that human pancreatic galactolipases release α-linolenic acid (ALA) as the main free fatty acid (≥35 %). NMR analysis indicated PUFA oxidation when microalgal endogenous enzymes were not inactivated before digestion. ALA oxidation into phytoprostanes occurred, especially after lipolysis. Thus, C. reinhardtii galactolipids are bioaccessible to digestive enzymes, making them a valuable PUFA source, provided oxidation is controlled.