Screening of Probiotics for Promoting Mineral Absorption Based on In Vitro Fermentation and Cell Models

Bin Liu¹Yuejian Mao²Jing Yang²Linjun Wu³Xiaoqiong Li³Xiangyu Bian³Jian Kuang³Jianqiang Li³Fangshu Shi³Ying Luo⁴Peiqing Jiang⁴Jinjun Li^3*Haibiao Sun^4*

• ¹First Hospital of Shanxi Medical University, Taiyuan, China
• ²China Mengniu Dairy Company Limited, Hohhot, China
• ³Zhejiang Academy of Agricultural Sciences, Hangzhou, China
• ⁴Shanxi Medical University, Taiyuan, China

Mineral deficiency is a major nutritional issue that threatens human health. Probiotics, owing to their ability to enhance intestinal absorption, are regarded as potential nutritional modulators. In this study, multiple strains of Lactobacillus and Bifidobacterium were systematically evaluated for their in vitro fermentation metabolism and mineral absorption–promoting properties, to screen probiotic candidates possessing mineral uptake–enhancing potential. The results revealed significant strain-specific differences in acid production capacity, short-chain fatty acids (SCFAs) generation, and phytase activity. Strains L. paracasei PC-01, B. lactis Ca360, L. plantarum Fe-01, B. lactis MN16620, and L. brevis MN14440 exhibited pronounced acid-producing ability, as indicated by markedly decreased fermentation broth pH values. Strains L. reuteri MN11965, L. acidophilus MN06785, L. brevis MN06618, and L. rhamnosus MN08244 showed significantly higher L-lactic acid yields than the positive control. SCFAs profiling demonstrated that acetate was the predominant metabolite, followed by propionic and Butyric acids, with strains L. curvatus MN15933, B. lactis Ca360, and B. lactis MN16620 showing particularly strong butyrate production. Phytase activity assays revealed that both intracellular and extracellular enzyme activities of L. plantarum Fe-01 and B. lactis Ca360 were significantly higher than those of strain L. plantarum 299v. Based on multi-parameter screening, eight strains (L. plantarum MN05018, L. plantarum Fe-01, L. plantarum MN05347, L. brevis MN14440, B. lactis MN16620, B. lactis Ca360, L. fermentum MN00735, and L. paracasei PC-01) were selected for further evaluation of mineral absorption–promoting capacity using the Caco-2 cell model. All tested strains significantly increased calcium uptake, with L. plantarum Fe-01 and B. lactis Ca360 showing the highest transmembrane calcium transport efficiency. These two strains also markedly enhanced iron absorption, while B. lactis Ca360 exhibited zinc uptake and transport levels comparable to the positive control. Comprehensive analysis indicated that strain B. lactis Ca360 demonstrated the most prominent effect in promoting calcium, iron, and zinc absorption, likely through mechanisms involving acid production–induced pH reduction and phytate hydrolysis facilitation. This study provides systematic verification of the integrated mechanisms by which probiotics promote mineral absorption and offers both theoretical support and strain resources for the development of targeted probiotics aimed at improving mineral bioavailability.