The consumers' demand for natural flavour and fragrances rises. To be natural, compounds have to result from the extraction of natural materials and/or to be transformed by natural means such as the use of enzymes or whole cells. Fungi are able to transform some fatty acids into lactones that can thus be natural. Although some parts of this subject have been reviewed several times, the present article proposes to review the different pathways utilised, the metabolic engineering strategies and some current concerns on the reactor application of the transformation including scaling up data. The main enzymatic steps are hydroxylation and β-oxidation in the traditional way, and lactone desaturation or Baeyer-Villiger oxidation. Although the pathway to produce γ-decalactone is rather well known, metabolic engineering strategies may result in significant improvements in the productivity. For the production of other lactones, a key step is the hydroxylation of fatty acids. Beside the biotransformation, increasing the production of the various lactones requires from biotechnologists to solve two main problems which are the toxicity of lactones toward the producing cell and the aeration of the emulsified reactor as the biochemical pathway is very sensitive to the level of available oxygen. The strategies employed to resolve these problems will be presented.

The plastidial methylerythritol phosphate (MEP) pathway is an essential route for plants as the source of precursors for all plastidial isoprenoids, many of which are of medical and biotechnological importance. The MEP pathway is highly sensitive to environmental cues as many of these compounds are linked to photosynthesis and growth and light is one of the main regulatory factors. However, the mechanisms coordinating the MEP pathway with light cues are not fully understood. Here we demonstrate that by a differential direct transcriptional modulation, via the key-master integrators of light signal transduction HY5 and PIFs which target the genes that encode the rate-controlling DXS1, DXR and HDR enzymes, light imposes a direct, rapid and potentially multi-faceted response that leads to unique protein dynamics of this pathway, resulting in a significant difference in the protein levels. For DXS1, PIF1/HY5 act as a direct activation/suppression module. In contrast, DXR accumulation in response to light results from HY5 induction with minor contribution of de-repression by PIF1. Finally, HDR transcription increases in the light exclusively by suppression of the PIFs repression. This is an example of how light signaling components can differentially multi-target the initial steps of a pathway whose products branch downstream to all chloroplastic isoprenoids. These findings demonstrate the diversity and flexibility of light signaling components that optimize key biochemical pathways essential for plant growth.

From the first observation about 40 years ago that yeast cells were interesting protective structures that could be used in several industrial applications, processes have been developed enabling technologists to incorporate several compounds possessing different physico-chemical (hydrophobic/hydrophilic) properties. Technologists screened yeast diversity to choose strains possessing the best potential and modified their physiological state to increase the uptake capability and the envelope plasticity, for instance by increasing the amount of lipids. Physico-chemical treatments were also used to improve the uptake and decrease the yeast natural material impact on the final products. For example, yeast cells could be "emptied" of their plasmic material. Yeast cells can also be coated with an additional polymeric material to increase resistance to heat treatment or decrease material liberation.These capsules can be used for several applications including carbonless paper, perfuming tissues and drug targeting, but the main industrial application deals currently with flavour encapsulation, although encapsulation in yeast is also interesting for the global food industry trend for health products.This paper proposes to review the use of yeast as an encapsulation structure focusing particularly on the properties of the yeast capsule and their impact on loading, protection, targeting and release.