Physicochemical property and in vivo prebiotic function of α‐(1 → 2) and α‐(1 → 3)‐branched dextran derived from <i>Leuconostoc citreum</i> <scp>KD3</scp>

Abstract Background We isolated lactic acid bacteria (LAB) from Japanese traditional fermented foods and vegetables, and screened for exopolysaccharide (EPS)‐producing strains. The Leuconostoc citreum KD3 was isolated as a strain that produces an α‐glucan (KD3‐dextran) with α‐(1 → 6)‐linked main chain with a considerable amount of α‐(1 → 2) branches. This type of polysaccharide has not been well investigated for its in vivo health benefits. We therefore evaluated in vivo digestibility of KD3‐dextran and cecal short‐chain fatty acids (SCFA) property by conducting a mice study, as well as in vitro physical properties including molecular weight and viscosity. Results 1 H‐NMR analysis showed that KD3‐dextran is an α‐glucan with 84.3% of α‐(1 → 6) linkages, 13.1% of α‐(1 → 2) linkages and 2.5% of α‐(1 → 3) linkages. KD3‐dextran showed shear thinning viscosity comparable to hydroxypropyl methylcellulose at the same concentration at 25°C. Weight‐average molecular weight of KD3‐dextran was approximately 1,470,000. A single oral administration of KD3‐dextran to C57BL/6J mice revealed that KD3‐dextran undergoes slight digestion, similar to commercial dextran. Four‐week administration of KD3‐dextran to C57BL/6J mice increased cecal acetic (1.6‐fold) and propionic (2.0‐fold) acids. Conclusion We were the first to directly demonstrate in vivo that α‐1,2‐branched glucan enhances SCFA levels in the mouse cecum. These results revealed the industrially useful properties and functionality of KD3‐dextran and indicated that KD3‐dextran is a promising prebiotic ingredient.