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Abstract

AbstractBiotechnology of flavonoidsVerveridis et al., Biotechnol. J. 2007, 2, 1214–1234Plant natural products derived from phenylalanine and phenylpropanoid are important in plant growth, development, and responses to environmental stresses, and thus can have large impacts on agricultural productivity. While plant‐based medicines containing these components have long been used by humans, the benefits of specific flavonoids to human health have only been recognized more recently. Researchers from Heraklion (Crete, Greece) provide a review in two parts, where they discuss the diversity, biosynthetic origins and activities of phenylpropanoids and flavonoids, referring to their effects on human health and physiology, and their roles as plant defense and antimicrobial compounds. In part II they discuss the use of biotechnological tools targeting the rational reconstruction of multienzyme pathways in order to modify the production of such compounds in plants and model microbial systems for the benefit of agriculture and forestry.Microbial production of natural raspberry ketoneBeekwilder et al., Biotechnol. J. 2007, 2, 1270–1279Raspberry ketone is frequently used in soft drinks, sweets, puddings and ice creams. Researchers from Wageningen (The Netherlands) have now isolated candidate genes potentially linked to raspberry ketone synthesis and introduced them into bacterial and yeast expression systems. Conditions have been determined that result in significant levels of raspberry ketone, up to 5 mg/L. These results therefore lay a strong foundation for a potentially renewable source of “natural” flavour compounds making use of plant genes. Future efforts will be focused on expression of this plant‐specific pathway in food‐grade micro‐organisms, such as Lactococcus lactis.Yeast oxidase effecting lactone productionGarcía et al., Biotechnol. J. 2007, 2, 1280–1285β‐Oxidation is a cyclic pathway involved in the degradation of lipids. In yeast, it occurs in peroxisomes and the first step is catalyzed by an acyl‐CoA oxidase (Aoxp). The yeast Yarrowia lipolytica possesses several genes (POX) coding for Aoxps. This study by French researchers is based on the factorial analysis of results obtained with existing POX derivative strains. The effect of interactions between Aoxps on the acyl‐CoA oxidase (Aox) activity is important even at the second order. Aox activity is correlated with acidification of the medium by cells and with cellular growth but not with lactone production, although Aox activity on short chains is inversely correlated with lactone accumulation.