Biosynthesis and prebiotic activity of a linear levan from a new Paenibacillus isolate.

Levan, a type of β (2→6)-linked fructan, is a promising biopolymer with distinct properties and extensive applications in the fields of food, pharmaceutical, cosmetics, etc. However, the commercial availability of levan is still limited due to the relatively high production costs. Here, a new Paenibacillus sp. strain FP01 was isolated and identified as an efficient fructan producer with high yield (around 89.5 g/L fructan was obtained under 180 g/L sucrose) and conversation rate (49.7%). The fructan named Plev was structurally characterized as a linear levan-type fructan with a molecular mass of 3.11 × 106 Da. Aqueous solutions of Plev exhibited a non-Newtonian behavior at concentrations 3–5%. Heating and chilling had no obvious effects on apparent viscosities of Plev solutions. Plev also had good rheological stabilities toward pH (3–11) and metal salts (Na+, K+, Ca2+, Mg2+). Microbiome and metabolome analysis showed that Plev intervention increased the abundance of beneficial bacteria and elevated the levels of short-chain fatty acids (SCFAs) in feces of mice. Taken together, Plev could be considered a potential thickener and prebiotic supplement in food industry. Key points • Paenibacillus sp. strain FP01 was identified as a high-efficient levan producer. • The levan Plev from FP01 exhibited good rheological properties and stabilities. • The in vivo prebiotic activities of linear levan were revealed.