Extraction of fungal polyketide pigments using ionic liquids.
Résumé
Filamentous fungi have been widely recognized as promising sources of various types of
biomolecules and are therefore highly investigated. The production of fungal pigments is one
intensively studied domain in order to respond to the growing demand for natural colorants as
substitutes to synthetic dyes used in food, cosmetics, pharmaceutical and textile industries. Such
interest in the natural origins of the pigments is driving the search for new and greener extraction
systems. It is desired to develop extraction processes that would use less organic solvents and
milder conditions, allow higher and quicker extraction yields, as well as improved selectivity and
better recovery. Over the last two decades, ionic liquids (ILs) have caught attention as novel green
solvents, and have already been applied in various separation systems (membranes separation,
additives in mobile phase and surface-bonded stationary phases in chromatography) [1]. ILs are
molten salts that can display a vast variety of chemical properties based on the specific association
of a bulky and asymmetric organic cation with an organic or inorganic anion. The use of an
aqueous two-phase systems (ATPS) based on ionic liquids allows to tailor the extraction system to
the pigmented molecule of interest, here fungal pigmented polyketides. In this study, several ATPS
based on quaternary ammonium ([N4444]Br-) and immidazolium ([C4Mim]Cl- and [C4Mim]Br-)
ionic liquids were investigated for the efficient extraction and recovery of soluble polyketides
pigments from the fermented broth of four fungal strains: Talaromyces albobiverticillius,
Emericella purpurea, Penicillium marquandii, Trichoderma harzianum. These four families are
known to produce mainly polyketides pigments such as azaphilone and hydroxyanthraquinone
pigments, which are the main targets in the field of fungal pigments research [2,3]. The extraction
efficiency of red, orange and yellow hues was investigated with a particular focus on the soluble
red pigments extraction efficiency and recovery from the three different ATPS tested. The results
showed that extraction yields of extracellular pigments of all hues from all strains are greater than
80%, with [N4444]Br- and [C4Mim]Cl- reaching between 90 and 100% extraction efficiencies.
Moreover, these two IL-based ATPS tend to preferably isolate red pigments under alkaline
conditions, which is in agreement with previous studies [4]. The second step of this study, which
focused on the recovery of the different pigments from the ILs, remains under investigation as the
affinity of the IL for the pigmented molecules seems high and difficult to reverse.
Nevertheless, the initial results of this study bring novel strategies for the selective extraction of
extracellular fungal pigments. As a next step, further investigation would be required in
determining the specific solubility of azaphilones and hydroxyanthraquinones-like molecules in the
different ILs.
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2016 POSTER Ionic liquids & fungal pigments, Book of abstracts CONGRESS Pigments in Food.pdf (8.42 Mo)
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