Limonene production in microalgal photoautotrophic cultivation / Produção de limoneno em cultivo fotoautotrófico microalgal

Abstract

There is a worldwide consensus in the food industry that aims to replace synthetic ingredients with natural ingredients for health promotion. The industrial relevance of microalgae as sources of extensive spectrum of bioproducts and as promising raw materials for the production of natural additives is constantly growing. Limonene, due to its proven safety, makes it widely exploitable in the food, cosmetics and pharmaceutical industries, for exhibiting vast biological activity, with beneficial effects on health. Some microalgae produce this biocompound from the isoprenoid pathway through the action of the enzyme limonene synthase (LMS) from geranyl-pyrophosphate (GPP). Therefore, the aim of the study was to investigate the formation of the volatile compound limonene, derived from six microalgae, from photoautotrophic cultivation, as well as to evaluate its odor properties. The experiment was carried out in a bioreactor with BG11 medium. The incubation conditions used were 25°C, photon flux density of 25 μmol.m -2 .s-1 , aeration of 1VVM (air volume per volume of medium per minute) and light cycle of 24:0h (bright:dark). Volatiles were isolated by headspace solid phase microextraction, separated by gas chromatography, identified by mass spectrometry (SPME-GC-MS) and their odor significance was evaluated based on the NIST spectrum library. Limonene was identified in the volatile fraction of the six microalgae, contributing positively to the aroma (citrus and mint), demonstrating high biotechnological capacity to obtain an alternative of this natural biocompound with commercial viability, with the microalgae Scenedesmus bijuga being the one with the greatest quantitative potential.