Selenium-Enriched Akkermansia muciniphila: A Novel Probiotic Bacterium for Se Supplementation

Selenium (Se)-enriched probiotics have gained widespread application in the fields of food, nutraceuticals, and biomedicine due to their capacity to deliver organic Se with high nutritional value to their hosts. Here, the inorganic Se bioconcentration was employed to generate Se-enriched Akkermansia muciniphila (Se-AM), and we investigated its Se distribution, selenoprotein and selenoamino acid species, essential elements, and amino acid contents. Furthermore, the major probiotic properties of Se-AM were evaluated. The results showed that the Se-AM exhibited remarkable survival and Se enrichment levels. The organic Se content in Se-AM accounted for approximately 81.9%, predominantly composed of protein bound Se (44.3%), followed by nucleic acid bound Se (17.8%) and polysaccharide bound Se (17.4%). The Se element in Se-AM exhibits a preference for binding to proteins with medium molecular weight, predominantly forming selenoamino acids containing SeCys2 and SeMet. Moreover, the content of both individual and total amino acids is higher in Se-AM compared to AM. Furthermore, Se-AM demonstrates robust acid resistance and antioxidant activity along with enhanced adhesion to Caco-2 and HT-29 cells. It also possesses immune-stimulating properties by activating the TLR4/NF-κB signaling pathway in Raw 264.7 cells, leading to increased cytokine release. Transcriptomic analysis reveals elevated expression levels of key genes associated with potent antioxidants, strong cellular adhesion capabilities, and effective cancer cell eradication within Se-AM when compared to AM. Our findings indicated that the Se-AM holds promising potential as a novel probiotic formulation supplemented with Se for both its Se-enhancing properties and probiotic functionality.