A New Approach to Producing High Yields of Pulcherrimin from Metschnikowia Yeasts

Abstract

Pulcherrimin, a red iron chelate, is produced by some yeasts and bacteria. It plays important ecological roles in many ecosystems, including growth control, biofilm inhibition and photoprotection. In this study, fifteen yeast strains of the genus Metschnikowia were characterized based on their production of pulcherrimin. Yeast pulcherrimin was isolated and its purity assessed using 1H nuclear magnetic resonance spectroscopy. Under experimental conditions, pulcherrimin formation varied depending on both the tested strains and culture media. The best producers formed up to 240 mg/L of pulcherrimin in minimal medium with glucose as the carbon source, supplemented with 0.05% FeCl3 and 0.1% Tween 80. This study presents a new approach to producing high yields of pulcherrimin from yeasts.

Biological Activity of Pulcherrimin from the Meschnikowia pulcherrima Clade

“…Three Metschnikowia strains with different levels of pulcherrimin productivity were selected for this study [ 6 ]. In the absence of Fe(III) ions, the survival of the yeasts after UV treatment was very low and did not exceed 10%.…”

“…The iron-binding molecule pulcherrimin was described a century ago, but it is still not known which genes are responsible for its production [ 17 ]. The production of pulcherrimin is strongly dependent on the composition of culture media and other culture cultivation factors [ 6 , 14 , 18 , 19 ].…”

“…Chemically, pulcherrimin is a ferric chelate or salt of pulcherriminic acid (2,5-diisobutyl-3,6-dihydroxypyrazine-1,4-dioxide), or a tautomeric form of that compound [ 5 , 6 ]. Pulcherrimin is very slightly soluble in water and insoluble in all organic solvents.…”

“…It has been noted that the depletion of iron by pulcherriminic acid and the formation of insoluble pulcherrimin pigment are important action mechanisms of biocontrol [ 4 , 8 , 9 , 10 ]. Pulcherrimin-producing yeast species of genera: Metschnikowia , Lipomyces , Kluyveromyces , and Dipodascopsis are considered effective antimicrobial agents against various microorganisms, with great potential for biocontrol applications—particularly in the phyllosphere, where these yeasts are frequently found [ 3 , 4 , 6 ].…”

“…Over the last decade, there have been numerous studies on the biocontrol ability and action mechanisms of large numbers of strains belonging to the M. pulcherrima clade, isolated from various substrates [ 11 , 12 , 13 ]. It has also been observed that the amount of pulcherrimin formed varies considerably within strains and may be a function of environmental conditions [ 2 , 6 , 14 , 15 ]. The strong antagonistic properties of pulcherrimin-producing strains have encouraged research into the other possible roles of this metabolite in natural habitats.…”