The invention provides an isolated and purified lactic acid bacteria, which isLactobacillusparacaseiPS23 (PS23) and its applications in delaying aging process, improving immunomodulatory activity, reducing, preventing or treating allergic, reducing, preventing or treating inflammation, preventing or treating a chronic disorder and/or preventing and/or treating a mood disorder or a neurological condition.本發明提供經分離且經純化之乳酸菌，其為副乾酪乳桿菌(Lactobacillus paracasei) PS23 (PS23)，及其在以下方面中之應用：延遲衰老過程；增進免疫調節活性；減少、預防或治療過敏；減少、預防或治療發炎；預防或治療慢性病症；及/或預防及/或治療情緒障礙或神經病狀。
