Tailoring fructooligosaccharides composition with engineered Zymomonas mobilis ZM4

Abstract

Zymomonas mobilis ZM4 is an attractive host for the development of microbial cell factories to synthesize high-value compounds, including prebiotics. In this study, a straightforward process to produce fructooligosaccharides (FOS) from sucrose was established. To control the relative FOS composition, recombinant Z. mobilis strains secreting a native levansucrase (encoded by sacB) or a mutated β-fructofuranosidase (Ffase-Leu196) from Schwanniomyces occidentalis were constructed. Both strains were able to produce a FOS mixture with high concentration of 6-kestose. The best results were obtained with Z. mobilis ZM4 pB1-sacB that was able to produce 73.4 ± 1.6 g L^-1 of FOS, with a productivity of 1.53 ± 0.03 g L^-1 h^-1 and a yield of 0.31 ± 0.03 g_FOS g_sucrose^-1. This is the first report on the FOS production using a mutant Z. mobilis ZM4 strain in a one-step process. KEY POINTS: • Zymomonas mobilis was engineered to produce FOS in a one-step fermentation process. • Mutant strains produced FOS mixtures with high concentration of 6-kestose. • A new route to produce tailor-made FOS mixtures was presented.

Keywords: 6-kestose; Fructooligosaccharides (FOS); Levansucrase (sacB); One-step fermentation; Schwanniomyces occidentalis (Ffase-Leu196); Zymomonas mobilis.