Low-calorie sugars produced by lactic acid bacteria

GINO VRANCKEN; TOM RIMAUX; LUC DE VUYST; FERNANDA MOZZI

Biotechnology of Lactic Acid Bacteria. Novel Applications

Wiley-Blackwell Publishing

Lugar: Ames, Iowa, USA; Año: 2010; p. 193 - 209

Mannitol, sorbitol, and erythritol are naturally occurring sugar alcohols. Mannitol is produced by bacteria, yeasts, fungi, algae, and several plants. This polyol might help these organisms to cope with different environmental stresses such as osmotic and oxidative stress. Sorbitol is produced by both a variety of plants and microorganisms. Erythritol production is usually associated with yeasts, but has also been reported for some lactic acid bacteria (LAB). All these polyols display beneficial human health properties, as they are non-metabolizable, insulin-independent sweeteners or low-calorie sugars, which make them applicable in dietetic and diabetic food products. In addition, mannitol is used in the pharmaceutical industry as a powerful osmotic diuretic agent and as an osmotic agent to decrease brain and cellular edema. Mannitol biosynthesis through bacterial fermentation has become an interesting alternative to the existing chemical production. Chemical synthesis using a nickel catalyst-assisted hydrogenation shows several economic disadvantages, such as high production costs and low product recovery. Furthermore, the capability of certain LAB, belonging to both homo- and heterofermentative species, to synthesize mannitol, offers the possibility of in situ mannitol production in foods. For this reason, different fermentation technology-based strategies for improving mannitol production by LAB have been reported. To date, achievements up to 93-97 mol% mannitol yields are reached using a bioprocess with a heterofermentative LAB strain. Moreover, metabolic engineering of food-grade lactate dehydrogenase-deficient mutants, has been reported, in particular for sorbitol production by LAB. This chapter deals with the state-of-the-art of sugar alcohol production by LAB (mannitol, sorbitol, and erythritol), as interesting low-calorie food ingredients. In addition, the strategies employed to increase their production and application in food and pharmaceutical products or to further design new functional foods, naturally enriched in mannitol, will be dealt with.