A Determination of the Optimal Conditions for the Purification and Recovery of Lactobionic acid from Whey

Abstract

This study explored the biotechnological production of lactobionic acid through the oxidation of whey, a by-product generated during milk and dairy processing, using the bacterium Gluconobacter frateurii. The bacterial strain used in the experiments was isolated from rotten apples. Identification was carried out by PCR amplification of the 16S rRNA gene, followed by nucleotide sequencing. Comparison of the obtained sequence with those in the NCBI GenBank database confirmed, with 99% similarity, that the isolated microorganism was Gluconobacter frateurii. The identified strain was cultivated in liquid whey-based media to assess its capacity for lactobionic acid production. Based on bacterial growth and cell count analysis, whey derived from industrial acid-treated curd was determined to be the most suitable substrate. The bacterium Gluconobacter frateurii was grown in pretreated whey medium, and lactose concentrations were monitored at 24, 36, 48, 60, 72, 84, 98, 115, and 154 hours after the onset of fermentation. The lowest lactose concentration, 1.18 g/L, was observed after 115 hours, indicating that a fermentation period of approximately four days is sufficient under liquid culture conditions. Following the completion of fermentation, the formation of lactobionic acid was confirmed using thin-layer chromatography (TLC). The product was then isolated through recrystallization, achieving a lactose conversion yield of 74%. The purified lactobionic acid was further analyzed to determine its physicochemical properties and biological activity. This research demonstrates that whey, commonly regarded as a waste product of dairy manufacturing, can be effectively utilized through biotechnological methods to produce lactobionic acid, a high-value compound with important applications in the pharmaceutical and cosmetic industries.