Influencing factors and mechanisms of guanosine degradation by Lactiplantibacillus plantarum ST-11 from red sour soup

Using a guanosine-degrading strain ST-11 isolated from the naturally fermented red sour soup in Guizhou as the research object, the strain was identified through morphological observation and molecular biology techniques, and the degradation ability of the strain ST-11 to nucleosides and purine substances was determined by high performance liquid chromatography (HPLC). The different components of strain ST-11 (live cells, dead cells, and intracellular substances of the cells) were co-cultured with Caco-2 cells, and their effects on the guanosine degradation ability and the expression levels of related transport protein genes were investigated. The results indicated that the strain ST-11 was identified as Lactiplantibacillus plantarum, which could tolerate pH 2 and 0.3% bile salt conditions. The hydrophobic rate and self-aggregation rate were 53.22% and 82.94% respectively, and the adhesion rate to Caco-2 cells was 12%. The degradation rates of guanosine and inosine were 99.32% and 98.42% respectively, and the degradation of guanosine was mainly through intracellular absorption. Compared with the dead cells and intracellular substances of the cells, the live cells of strain ST-11 co-cultured with Caco-2 cells had the highest degradation rate of guanosine (99.65%). In addition, the live cells of strain ST-11 could inhibit the expression of messenger ribonucleic acid (mRNA) of glucose transporter 9 (GLUT9) and concentrated nucleotide transporter (CNT_S). In summary, L. plantarum ST-11 derived from red sour soup had the potential to lower uric acid.