The accumulation of organic selenium (Se) by lactic acid bacteria (LAB) showed excellent biosafety and absorption efficiency. Identification of Se-enriched strains and the production of Se-enriched products by fermentation are popular research areas. However, there are few studies that focus on the distribution characteristics of Se in cells. In this study, a Se-enriched dominant Lactobacillus Paracasei 20241 was selected to characterize the distribution of Se on the cell surface and inside the cell. The results showed that L. paracei can convert sodium selenite into zero-valent Se and organic Se. The former was then released outside the cell and the latter was combined with cell components. The content of organic Se in the cells was 2144.99 ± 123.16 μg/g, accounting for 52.73% of the total Se. Compared with cellular polysaccharide and nucleic acid, protein exhibited the highest Se binding ability of 864.03 ± 26.04 μg/g, indicating that the main form of organic Se was selenoprotein. Thus, Lactobacillus Paracasei 20241 is expected to be used as a dietary supplement for Se-enrich biomass probiotics.

乳酸菌（LAB）对有机硒（Se）的积累表现出优异的生物安全性和吸收效率。富硒菌株的鉴定和通过发酵生产富硒产品是热门的研究领域。然而，很少有研究关注硒在细胞中的分布特征。在这项研究中，选择了富硒的优势副干酪乳杆菌 20241来表征硒在细胞表面和细胞内部的分布。结果表明，L. paracei可将亚硒酸钠转化为零价硒和有机硒。前者然后释放到细胞外，后者与细胞成分结合。细胞内有机硒含量为2144.99±123.16 μg/g，占总硒的52.73%。与细胞多糖和核酸相比，蛋白质对硒的结合能力最高，为864.03±26.04 μg/g，表明有机硒的主要形式是硒蛋白。因此，Lactobacillus Paracasei 20241 有望用作富硒生物质益生菌的膳食补充剂。