In Situ Detoxification of the Fermentation Medium during γ-Decalactone Production with the Yeast Sporidiobolus salmonicolor

Abstract

gamma-Decalactone (gamma-C10) is known to be highly toxic for the microorganims used for its production. In this work, three techniques were studied in order to overcome this toxicity during a bioconversion process using ricinoleic acid as precursor of the lactone: in situ trapping in oily phases, in porous hydrophobic sorbents and in beta-cyclodextrins. Oily phases added to the media (olive, Miglyol, tributyrin, and paraffin) had a protective effect on Sp. salmonicolor, and they improved the lactone production. beta-cyclodextrins, which have a hydrophobic cavity that can trap molecules such as gamma-C10, have been used to protect the yeasts. The results showed insufficient preservation of cell viability. Some sorbents (activated carbon and polystyrene-based sorbents) were successfully tested during bioconversion. In all cases viability exceeded the reference one. Nevertheless the aroma production was 30% lower than the reference. All of these solutions led to some enhancement of the cell viability during bioconversion of methyl ricinoleate to gamma-C10. For improvement of the lactone production, the oil trapping method seemed to be the best with the experimental conditions tested.

Catabolism of hydroxyacids and biotechnological production of lactones by Yarrowia lipolytica

“…The decline in cell viability has been clearly associated with the increase in lactone concentration within culture media during biotransformation DufossØ et al 1999). Moreover, the antimicrobial properties of some (Nago et al 1993).…”

“…Some strategies have been developed to reduce lactone toxicity within the fermentation medium, as for example the addition into the culture media of inert oils (hydrogenated coconut oil or a mixture of tripalmitine, tristearine, triolein) or hydrophobic porous sorbents (DufossØ et al , 1999Souchon et al 1998). Such techniques enable the improvement of yeast viability, by trapping the hydrophobic lactones and so by decreasing their concentration within the aqueous phase.…”

The use of Macronet resins to recover γ-decalactone produced by Rhodotorula aurantiaca from the culture broth

“…Previous studies reported the adsorption of -decalactone onto activated carbon and hydrophobic resins (Porapak Q, Chromosorb 105 and SM4) by online extraction. However, while they limited the toxicity of the lactone towards the yeast, their presence in the bioconversion medium also decreased the production of -decalactone [8,9].…”

Production of Dicarboxylic Acids and Flagrances by Yarrowia lipolytica

“…The fact that a γ-hydroxy acid tends to lactonise readily is important to explain the production, but it does not prevent the cyclised lactone from re-entering β-oxidation. This degradation possibility is a major problem encountered by biotechnologists, and several works have been carried out to extract γ-decalactone during production (Druaux et al 1995;Dufossé et al 1997Dufossé et al , 1999Souchon et al 1998). Indeed, the strategy consisting in modifying the strain to avoid degradation is usually impossible as β-oxidation is a pathway in which the same enzymes are active from C18 to C4 and deleting the gene coding for one β-oxidation enzyme would simply stop the pathway at the C18 level (as done for the production of dicarboxylic acids).…”