Effects of different stress conditions on the production, bioactivities, physicochemical and structural characteristics of exopolysaccharides synthetized by Schleiferilactobacillus harbinensis Z171

This study systematically investigated the effects of stress conditions including temperature, pH, H2O2, NaCl, antibiotics on the production and in vitro cholesterol-lowering activity of the exopolysaccharide (EPS) synthetized by Schleiferilactobacillus harbinensis Z171. Additionally, the influences of the optimal stress condition combined with different carbon sources on EPS production were examined, shedding light on the structural characteristics, physicochemical properties and bioactivities of EPSs. The results demonstrated that the EPS produced under H2O2 stress was optimal and presented excellent resistance to simulated gastric juice and α-amylase. Three main fractions, denoted as G-EPS1, F-EPS1 and S-EPS1, were isolated by cellulose DEAE-52 chromatography from crude EPSs synthetized using glucose, fructose and sucrose as carbon sources, respectively. Among them, F-EPS1 possessed the highest cholesterol-lowering, antioxidant and hypoglycemic activities, with the highest molecular weight 91.03 kDa, largest particle size 40.14 nm and apparent viscosity 288.2 mPa·s. Three EPSs exhibited irregular sheet-like and granular structures with good thermal stability. Structural characterization of F-EPS1a (a purified fraction from F-EPS1) revealed that it was a mannan mainly composed of →2)-α-D-Manp-(1→, →3)-α-Manp-(1→ and →2,6)-α-D-Manp-(1→ with branch chains containing α-D-Manp-(1→. F-EPS1a has more potential to be a natural cholesterol-lowering, hypoglycemic and antioxidant supplements in the food industry.

Optimization of bioprocess of Schleiferilactobacillus harbinensis Ca12 and its viability in frozen Brazilian berries (Açai, Euterpe oleracea Mart.)

Amazonian palm berries (açaí, Euterpe oleracea Mart.) are fruits with high nutritional value and antioxidant activity and have aroused the interest of consumers, popularizing fruit pulps enriched with probiotics. Amazonian palm berries (açaí, Euterpe oleracea Mart.) are fruits with high nutritional potential, providing a source of carbohydrates, fibers, proteins, lipids, vitamins, and minerals. Furthermore, açai provides several health benefits, including antioxidant activity. Nutritionally enhanced foods have aroused the interest of consumers, popularizing fruit pulps enriched with probiotics. Probiotics are dietary supplements consisting of live, beneficial microorganisms in the host which improve the intestinal microbiota. The objective of this study was to isolate, identify, and characterize the probiotic potential of an isolated Schleiferilactobacillus harbinensis strain (dubbed Ca12) and provide an optimized bioprocess for its production, using the complete factorial and central rotational compound design to supplement the frozen açai pulp. The isolated strain S. harbinensis Ca12 presented adequate resistance to gastric juice and bile salts, microbial activity against different Candida strains, self-aggregation and coaggregation properties, high adhesion in HT-29 cells, and 35% inhibition of Salmonella in HT-29 cells. When optimized, the cellular biomass production of the S. harbinensis Ca12 strain was approximately 600% higher than the unsupplemented whey, with a production of 3.6 × 1010 CFU mL^-1. The S. harbinensis Ca12 strain's viability in the creamy and traditional frozen açai pulp was shown to be stable for up to 6 months at 20 °C. The impact of this study involved for the first time the S. harbinensis Ca12 described in the Brazilian cocoa pulp with activity against Candida albicans of clinical importance, creating the potential of a new functional food with important benefits to human health as prevention for candidiasis.