Impact of surfactants on the biotransformation of methyl ricinoleate into γ-decalactone by Yarrowia lipolytica

Abstract

Surfactants play a key role in the biotechnological degradation of hydrophobic substrates, however this role is often misunderstood. During the biotransformation of methyl ricinoleate into the aroma compound ␥-decalactone by the yeast Yarrowia lipolytica, a direct contact occurs between the surface of the cells and the small droplets of substrate. The impact of a series of surfactants on this process was investigated. Both ionic surfactants tested were toxic towards the yeast. This effect may be linked to a decrease in the cell membrane integrity. The interfacial area of the emulsion varied according to the non-ionic surfactant used, and this factor was correlated with the productivity of the biotransformation. By evaluating the effect of surfactants on the capacity of the cells to adhere to decane (MATH test), it was shown that the adhesion of methyl ricinoleate on yeast surface is not a rate-limiting point for the process.

Surface properties of Yarrowia lipolytica and their relevance to ?-decalactone formation from methyl ricinoleate

“…The cells' surface characterization has often been done in a relative manner by determining the percentage of adherence of a whole cell population to hydrocarbons or solvents (Bellon-Fontaine et al 1996), as we also did in previous work: correlations between the lactone productivity (Aguedo et al 2004) or the growth lag phase of Y. lipolytica (Wache´et al 2000) and the interfacial surface of the substrate were evidenced. However, it was then hypothesized that the yeast assimilates the lipids through mechanisms requiring polar interactions, since an increase in the adhesion lipids/cells was associated mainly with an increase in Lewis acid-base interactions .…”

Application of a Novel Oscillatory Flow Micro-bioreactor to the Production of γ-decalactone in a Two Immiscible Liquid Phase Medium

“…Pre-cultured cells of Yarrowia lipolytica W29 (ATCC20460; CLIB89) in the late growth-phase (19 h) were washed (6000 g, 5 min) three times with water and transferred to the biotransformation medium, consisting of: 10 g methylricinoleate l )1 , 2.5 g NH 4 Cl l )1 , 6.7 g YNB l )1 and 1 g Tween80 l )1 (Aguedo et al 2004). Initial $1-2 Â 10 8 cells ml )1 was pumped to a SPC tube and the biotransformations were carried out in batch mode and controlled at 27°C.…”

“…As the substrate is emulsified, droplet size may exert a limitation in the biotransformation process, where the interfacial area between the organic and aqueous phases is important for mass transfer: not only to favour the access of yeast to substrate but also to extract the produced c-decalactone (Aguedo et al 2004).…”

“…The fluid was subjected to different oscillation conditions, as mentioned in Table 1. The concentration of c-decalactone was assessed by L-L extraction with diethyl ether followed by GC analysis (Aguedo et al 2004). Error bars correspond to standard deviation of samples during replicated GC assessment.…”

“…As a proof-of-concept, this reactor was applied to the biotechnological production of c-decalactone, which consists on the biotransformation of methyl ricinoleate by the yeast Yarrowia lipolytica (Aguedo et al 2004). c-Decalactone is a fruity (peach-like) aroma compound, thus of great interest for the flavour industry, as illustrated by the numerous existing patents (Fickers et al 2005).…”