Influence of acid depolymerization parameters on levan molar mass distribution and its utilization by bacteria

摘要

Levan is a fructan composed of beta-(2, 6) linkages in its main chain. Its health properties, especially its prebiotic potential can be partially modified by changing its molar mass distribution. Given that native levan is rarely fermented by probiotic bacteria, especially lactic acid bacteria (LAB), levanoligosaccharides (LOS) were produced by mild acid hydrolysis. The response surface methodology (RSM) was applied to determine the optimum parameters for depolyrnerization. Gel permeation chromatography (GPC) was used to characterize the LOS produced and to show the differences between inulin and levan. The prebiotic potential of four fractions of LOS with different molar mass distributions was investigated. MRS (Mann Rogosa Sharpe) medium supplemented with the LOS were inoculated with bacterial strains and growth was monitored by measuring the turbidity of the cultures. The utilization of oligofructans was also confirmed by RP-UHPLC-UV-ESI-MS (liquid chromatography coupled with mass spectrometry) measurements of LOS derivatized with 1-phenyl-3-methyl-5-pyrazolone (PMP). It was observed that the degree of polymerization of LOS has an influence on the growth of the tested bacteria.