Enhanced Viability of Probiotics against Gastric Acid by One-Step Coating Process with Poly-L-Lysine: In Vitro and In Vivo Evaluation

Due to their low acid tolerance, a majority of probiotics face difficulties with regard to surviving in the gastric environment long enough to reach the intestinal surfaces where they colonize and provide health benefits. We prepared a probiotic delivery system that can enhance their viability in acidic conditions by developing a one-step poly-L-lysine (PLL) coating process. We determined whether the coating process was successful by measuring the zeta potential and observing it with confocal scanning microscopy. PLL-coated L. plantarum (PLL-LP), incubated in a solution of pH 2 for 2 h, exhibited a higher viability (6.86 ± 0.12 log CFU/mL of viable cells) than non-coated L. plantarum (non-coated LP), which exhibited only 2.7 ± 1.23 log CFU/mL of viable cells. In addition, a higher amount of L. plantarum was detected in the feces of mice orally administered PLL-LP (6.2 ± 0.4 log CFU/g of feces) than in the feces of the control groups. In addition to enhancing probiotic viability in pH 2 solution, the PLL coating showed no effect on the probiotic growth pattern and the viability of either freeze-dried L. plantarum or L. plantarum, stored at −20 °C and 4 °C, respectively. Overall, these results indicated that the PLL coating is a promising potential probiotic delivery system.