Production of "natural" aromas by filamentous fungi

Many micro-organisms, whether bacteria, yeasts or filamentous fungi, have long been known to produce particular odors, pleasant or unpleasant, when cultured.

The existence of species names such as "suaveolens", "fragrans" or "putrefaciens" clearly illustrates these odoriferous properties. These observations gave rise to the idea of producing flavors by biotechnological means, a promising alternative to chemical synthesis and extraction from plant raw materials, enabling us to obtain molecules with the "natural" label.

The principle of microbial flavor production is as follows: after being cultivated on a sweet nutrient medium, microorganisms are able to synthesize flavor "de novo" or by biotransformation of a substrate (containing flavor precursors) added to the culture medium. The odorant molecules are then recovered by distillation or solvent extraction.

Among micro-organisms, filamentous fungi, and in particular white wood-rot fungi (the only organisms capable of completely degrading lignin), are capable of synthesizing a broad spectrum of aromas very similar to those found in plants, and very varied: aliphatic aromas (alcohols, aldehydes, ketones), benzene-ring aromas (such as vanillin or benzaldehyde) or terpenoids (such as linalool or citronellol).