Effect of Nutrients on the Growth of Selenium-Enriched <i>Lacticaseibacillus rhamnosus</i> L20

Abstract Selenium-rich probiotics have the dual role of selenium and probiotics, and show great development potential in dairy products. Using Lacticaseibacillus rhamnosus L20 as the experimental strain, the effects of sodium selenite concentration and fermentation time on the growth and selenium conversion rate of L. rhamnosus L20, as well as the effects of carbon and nitrogen sources, prebiotics and inorganic salts on its growth were studied. The results showed that the appropriate sodium selenite concentration and fermentation time were 20 μg/mL and 16 h, and its selenium conversion rate and viable count were 88.83% and 2.34×10 8 CFU/mL, respectively. Carbon sources (glucose and lactose), organic nitrogen sources (soy peptone and beef extract), inorganic nitrogen sources (urea and Triammonium citrate), prebiotics (galactooligosaccharides and inulin) and inorganic salts (dipotassium hydrogen phosphate and sodium acetate) were beneficial to the growth of L. rhamnosus L20, and its dry weight was greater than 1.95 g/L, which provides a reference for further optimization of the proliferation culture medium of L. rhamnosus L20.