Optimally lyophilized Lactobacillus plantarum SNUG 12071 survival under storage and gastrointestinal conditions

Abstract

A sufficient amount of viable probiotic bacteria must be delivered to the gut in order to exert beneficial health effects. Lyophilization in protective carrier materials can enhance probiotic viability in a strain-specific manner. We investigated the effects and interactions of three cryoprotective agents (CPA) (skim milk, sucrose, and sorbitol) in their ability to improve survival of a novel probiotic strain, Lactobacillus plantarum SNUG 12071, during the harsh lyophilization process using a 3-factor rotatable central composite design (CCD) and response surface methodology (RSM). After CCD-RSM analysis and validation, the stationary point of the response surface, 11.0% skim milk, 4.3% sucrose, and 5.7% sorbitol, was determined to be the optimal CPA formulation to maintain L. plantarum. The stationary point CPA formulation achieved 81.9% L. plantarum survival during 48 h lyophilization. In contrast, cells lyophilized with no CPA maintained only 22.3% survival, leading to an almost 60% increase in lyophilization survival. Storage stability of optimally lyophilized L. plantarum was assessed for 6 months at room temperature (25°C) and refrigerated (4°C) conditions. Viability decreased by 0.0 and 0.4-log cfu (colony forming units)·mL-1 in refrigerated and room temperature conditions, respectively, after 6-months of storage, showing successful stability in both storage conditions. Lyophilization with protective agents also showed significant promise in improving L. plantarum survival in gastrointestinal conditions. Lyophilization mitigated 86.2% of the 1.6-log cfu·mL-1 viability decrease observed in unprotected cells in 2.0% bile acid conditions. Lyophilized cells also minimized 98.4% of the dramatic 3.4-log cfu·mL-1 viability decrease experienced by naked L. plantarum in pH 2.0 conditions. The results of this study provided a novel CPA formulation and demonstrated the benefits of optimizing lyophilization conditions in order to improve probiotic viability during lyophilization, storage, and gastrointestinal conditions.