Production and Optimization of Hyaluronic Acid Extracted from Streptococcus thermophilus Isolates

Biopolymers, particularly exopolysaccharides produced by microorganisms such as bacteria, yeasts, and algae, have gained popularity in recent years due to their physical, chemical, and functional properties that are widely useful in food, industrial, cosmetic, and pharmaceutical systems. Hyaluronic acid is one type of these polysaccharide. This study investigated the optimal conditions for producing hyaluronic acid from the Streptococcus thermophilus bacterial strain. The isolated Streptococcus thermophilus were cultured on MRS broth, Skim milk, and M۱۷ broth with an addition of ۱% lactose. The diagnosed bacterial strains were grown in ۱۰۰ ml of culture media, placed in volumetric flasks of ۲۵۰ ml capacity, and incubated at ۴۲˚C for ۲۴ hours, pH ۶.۸, inoculum volume ۱%, and a vibrating incubator at ۱۵۰ rpm. After the end of the fermentation period, the isolation and purification of HA have performed accordingly: proteins were removed using ۱% trichloroacetic acid (TCA), and HA in the supernatant was collected by isopropanol precipitation. The collected HA was dialyzed against ultrapure water and lyophilized. The amount of acid produced was estimated. The results show that the best production of hyaluronic acid was from the S. thermophilus bacterial strain grown on the alternative medium containing whey at a ratio of ۴۵۰ ml/L and۷.۵ g/L yeast extract at ۴۰ ˚C, with a ۳% of inoculum volume and ۱۰۲×۱۰۸ colony-forming units/ml of bacterial cells, in pH ۶.۸ and agitation speed of ۱۵۰ rpm for ۱۸ h, which had the most significant effect on the fermentation process and gave the highest value of HA production of ۰.۵۹۸ g/L and biomass of ۶.۰۸ g/L. These results showed the best production method for HA to achieve maximal production yelled.

Keywords:

Hyaluronic acid , optimal conditions , S. thermophilus Bacteria Strain