Production of a Series of Long-Chain Isomaltooligosaccharides from Maltose by Bacillus subtilis AP-1 and Associated Prebiotic Properties

Bacillus subtilis strain AP-1, which produces a-glucosidase with transglucosidase activity, was used to produce a series of long-chain isomaltooligosaccharides (IMOs) with degree of polymerization (DP) ranging from 2 to 14 by direct fermentation of maltose. A total IMOs yield of 36.33 g/L without contabacillusmination from glucose and maltose was achieved at 36 h of cultivation using 50 g/L of maltose, with a yield of 72.7%. IMOs were purified by size exclusion chromatography with a Superdex 30 Increase column. The molecular mass and DP of IMOs were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Subsequently, linkages in produced oligosaccharides were verified by enzymatic hydrolysis with a-amylase and oligo-a-1,6-glucosidase. These IMOs showed prebiotic properties, namely tolerance to acidic conditions and digestive enzymes of the gastrointestinal tract, stimulation of probiotic bacteria growth to produce short-chain fatty acids and no stimulating effect on pathogenic bacteria growth. Moreover, these IMOs were not toxic to mammalian cells at up to 5 mg/mL, indicating their biocompatibility. Therefore, this research demonstrated a simple and economical method for producing IMOs with DP2-14 without additional operations; moreover, the excellent prebiotic properties of the IMOs offer great prospects for their application in functional foods.

Automated summary

Bacillus subtilis strain AP-1 was used to directly ferment maltose and produce long-chain isomaltooligosaccharides (IMOs) with a degree of polymerization (DP) ranging from 2 to 14. The yield of IMOs reached 36.33 g/L with a yield of 72.7% after 36 hours of cultivation using 50 g/L of maltose. These IMOs exhibited prebiotic properties, including tolerance to acidic conditions and digestive enzymes, stimulation of probiotic bacteria growth, and no stimulating effect on pathogenic bacteria growth. They were also found to be non-toxic to mammalian cells, indicating their biocompatibility. This research provides a simple and cost-effective method for producing IMOs and highlights their potential application in functional foods.