Tracing Lactobacillus plantarum within the intestinal tract of mice: green fluorescent protein‐based fluorescent tagging

Abstract Background Lactobacillus plantarum is an important probiotic with a variety of physiologic functions. Studies have focused on the effects of L. plantarum on host physiology and microbiota, but studies of the fate of strains after they enter the intestine are lacking. In this study, L. plantarum ST‐III was genetically engineered to express green fluorescent protein (GFP). Mice were administered ST‐III‐GFP, and fluorescence imaging was used to study the distribution, location and quantity of strains within 8 h after entry into the intestine. Results The results indicated that genetic modification did not affect the growth of ST‐III, tolerance to simulated gastric juice and intestinal fluid or tolerance to antibiotics (with the exception of chloramphenicol). Fluorescence imaging and colony counting indicated that ST‐III‐GFP can be detected in the small intestine 5 min after oral gavage. After 30 min, nearly all ST‐III‐GFP was located in the small intestine. After 1.5 h, ST‐III‐GFP was detected in both the cecum and large intestine. After 4 and 8 h, ST‐III‐GFP was mainly concentrated in the cecum and large intestine. Compared to the initial amount ingested, the survival rate of ST‐III‐GFP within the intestine of mice was 10% after 8 h. In addition, a strong linear relationship was found between the fluorescence intensity and the viable count of ST‐III‐GFP. Conclusions The obtained data indicate that the amount of ST‐III‐GFP can be estimated by measuring the fluorescence intensity of this novel strain within the intestinal tract. © 2020 Society of Chemical Industry