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

Sulforaphane is a beneficial but unstable bioactive compound that can be converted from glucoraphanin by Lactiplantibacillus plantarum. However, the sulforaphane conversion rate is low, and the conversion mechanism of L. plantarum remains unclear. This research utilized the adaptive laboratory evolution technology to enhance the sulforaphane conversion rate of L. plantarum. 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 L. plantarum 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.