Synthesis of fructooligosaccharides and oligolevans by the combined use of levansucrase and endo-inulinase in one-step bi-enzymatic system

• Levansucrase/endoinulinase bienzymatic system was developed to produce scFOSs and oligolevans.
• Bi-enzymatic process showed higher yield and productivity than the current available ones.
• Contribution of endo-inulinase to the efficiency of bi-enzymatic system was higher.
• Production of intermediate levans with appropriate MW by levansucrase was a prerequisite.
• Use of immobilized levansucrase resulted in higher yield of levan as compared to free one.

Levansucrase from Bacillus amyloliquefaciens and endo-inulinase from Aspergillus niger were used in a one-step reaction to produce short chain fructooligosaccharides (scFOSs) and oligolevans from sucrose. Levansucrase catalyzed the synthesis of levan, while endo-inulinase regulated the product molecular size. The bi-enzymatic system showed higher yield and productivity (67% w/w; 96 g/L/h) than the levansucrase enzymatic system (3.0% w/w; 0.8 g/L/h) alone. The contribution of endo-inulinase to the formation of scFOSs and oligolevans through its hydrolytic activity was higher than that of levansucrase through its acceptor reaction; however, the production of intermediate levans with appropriate MW by levansucrase was prerequisite. The maximal concentration of scFOSs was higher as compared to that of oligolevans. Among scFOSs, 6-kestose was the most dominant product. The use of immobilized levansucrase resulted in a lower production of scFOSs and higher yield of levan. The current study is the first to highlight the potential of levansucrase/endo-inulinase bi-enzymatic system.Industrial relevanceFunctional food products are receiving a substantial amount of interest from consumers. Considering the size of this market, the food industry sector could benefit considerably from improvements in the functional ingredients used to support the development of these health promoting food products. In this context, fructooligosaccharides (FOSs), a class of ingredients whose potential health benefits in terms of supporting intestinal health and reducing the risk of cancers are increasingly being recognized. However, commercially available FOSs are exclusively β-(2→1)-inulin-type prebiotics with short chains, which are mainly absorbed in the small intestine. β-(2→6) and neolevan-type-FOSs have shown prebiotic activities that surpass the current β-(2→1)-FOSs generation.The development of innovative bi-enzymatic process for the production of FOSs and β-(2→6)-oligolevans in the present study is of high interest. The developed bienzymatic system showed high yield and productivity for the production of FOSs and oligolevans from sucrose as abundant starting materials. These products being of high-degree of polymerization are expected to exhibit an increased colonic prebiotic persistence and reach the distal intestinal region where most of the chronic diseases are originated.