Engineering Zymomonas mobilis to produce tailor-made fructooligosaccharides

Abstract

[Excerpt] Background: Fructooligosaccharides (FOS) are promising prebiotics in the increasing market of functional food. Industrially, these compounds are produced from sucrose using fructosyltransferase (Ftase) or β-fructofuranosidase enzymes (Ffase) [1]. Although it is known that these compounds may have a great impact in health, it has also been described that the beneficial effects may depend on the relative FOS composition. Therefore, to obtain a product with high market value it is necessary to optimize not only the FOS yield, but also the composition of the mixture. The search for novel microbial strains that have high transfructosylation and/or produce FOS with different patterns is currently being investigated [2]. The generally regarded as safe (GRAS) bacterium Zymomonas mobilis represents an excellent recombinant expression system to produce FOS, since it contains native enzymes able to convert the non-prebiotic sugars (glucose and fructose) into added-value products, such as levan, sorbitol and ethanol [3,4]. This microorganism contains an extracellular sucrase/invertase (SacC) and an extracellular levansucrase enzyme (SacB) that converts sucrose into levan and FOS [5,6]. Although the heterologous production of FOS by different organisms has proven to be a successful strategy to optimize and change the FOS composition [7,8], there are no reports regarding the heterologous production of FOS by Z. mobilis. [...]