**5. Conclusions**

A new GAA-26-*O*-β-glucoside was produced from the *O*-glucosylation of GAA with recombinant BsGT110 isolated from *B. subtilis* ATCC 6633 under acidic conditions (pH 6). BsGT110 was the first GT identified as catalyzing the glycosylation of triterpenoid at the C-26 position. Moreover, the optimal reaction condition of BsGT110 was at pH 6, and it lost most of this activity at pH 8, implying that such GTs might only catalyze other triterpenoid substrates under acidic conditions.

**Supplementary Materials:** The following are available online. Table S1. NMR spectroscopic data for compound (**2**) in pyridine-d5 (600 MHz), Table S2. BsGT110 sequence comparison with candidate triterpenoid-catalyzing GTs and flavonoid-catalyzing GTs, Figure S1. The 1H-NMR (600 MHz) spectrum of compound (**2**) in pyridine-d5, Figure S2. The 13C-NMR (150 MHz) spectrum of compound (**2**) in pyridine-d5, Figure S3. The HSQC (600 MHz) spectrum of compound (**2**) in pyridine-d5, Figure S4. The HMBC (600 MHz) spectrum of compound (**2**) in pyridine-d5, Figure S5. Phylogenetic analysis using the Maximum Likelihood method.

**Author Contributions:** Conceptualization: T.-S.C. and T.-Y.W.; data curation: T.-S.C. and Y.-H.K.; methodology: Y.-H.K. and C.-M.C.; project administration: T.-S.C.; writing—original draft: T.-S.C., T.-Y.W., and C.-M.C.; writing—review and editing: T.-S.C., T.-Y.W., J.-Y.W., Y.-W.W., and C.-M.C.

**Funding:** This research was financially supported by grants from the Ministry of Science and Technology of Taiwan (Project No. MOST 108-2221-E-024-008-MY2).

**Conflicts of Interest:** The authors declare that they have no conflicts of interest.
