Abstract
There is growing interest in newly isolated lactic acid bacteria from natural sources and traditional food manufacturing and transformation. Streptococcus thermophilus is able to improve the safety of dairy products, showing antioxidant and antimicrobial properties and also to produce bioactive molecules, such as exopolysaccharides (EPSs), usable in foods applications. An integrated bioprocess development was performed using S.thermophilus D4, for the production of viable biomass and EPSs using a media optimized through design of experiments. Plackett-Burman screening method was used twice to optimize biomass and exopolysaccharide production. Different fermentation strategies (batch and fed-batch) were performed to increase yield and productivity. Fed-batch processes increased biomass production approximately 2.5- and 7.5-fold than batch processes with optimized and M17 media, respectively. Furthermore, a significant increase of 1.7- and 6-fold EPS biosynthesis was observed. Finally downstream processes based on membranes were conducted to purify bioactive molecules (EPSs) used on Caco-2 cells showing a significant effect in accelerating wound healing. Finally, purification and recovery of EPSs tested on Caco-2 cells. The results obtained confirm the potential of newly defined medium to replace M17, which has animal-derived nitrogen sources, for probiotic biomass and EPSs production with many applications in different fields.