Metabolomics and Transcriptomics Analyses Reveal the Mechanisms of Sulforaphane Conversion and Adaptive Strategies in the Absence of Glucose by <i>Lactiplantibacillus plantarum</i>

Sulforaphane is a beneficial but unstable bioactive compound that can be converted from glucoraphanin by <i>Lactiplantibacillus plantarum</i>. However, the sulforaphane conversion rate is low, and the conversion mechanism of <i>L. plantarum</i> remains unclear. This research utilized the adaptive laboratory evolution technology to enhance the sulforaphane conversion rate of <i>L. plantarum</i>. The results showed that an increase in the glucose replacement ratio significantly downregulated carbohydrate metabolism and upregulated amino acid metabolism. Transcriptomic analysis showed that the ALE-adapted strain significantly upregulated carbohydrate metabolism and amino acid metabolism. In the conversion pathway, glucoraphanin is imported into <i>L. plantarum</i> cells, and its glucose moiety is phosphorylated by bglF (the phosphate group may be derived from phosphoenolpyruvate via the phosphotransferase system). Subsequently, the S-glycosidic bond of phosphorylated glucoraphanin is hydrolyzed by bglA (6-phospho-β-glucosidase), followed by nonenzymatic rearrangement and sulfate elimination, ultimately yielding sulforaphane. This research can contribute to revealing the interaction mechanism between microorganisms and natural active substances.