Db 1 capillary column

E. coli JM109 (Takara, Shiga, Japan) was used for sequencing analysis, and E. coli BL21(DE3) (Takara), pColdTF (Takara), and pColdI (Takara) were used to express BmeTC^X genes. NMR spectra were recorded using a Bruker DPX 400 spectrometer (Billerica, MA, USA) at 400 MHz for protons (¹H) and 100 MHz for carbon (¹³C). GC–MS was performed on a JMS-T100GCV spectrometer (JEOL, Tokyo, Japan) equipped with a DB-1 capillary column (30 m × 0.25 mm × 0.25 µm; J&W Scientific. Inc., Folsom, CA, USA), using the EI mode operated at 70 eV. GC analyses were performed using a Shimadzu GC-2014 chromatograph equipped with a flame ionization detector and using a DB-1 capillary column (30 m × 0.25 mm × 0.25 µm; J&W Scientific, Inc.). GC and GC–MS conditions for the BmeTC^X products were as follows: injection temperature = 300 °C, column temperature = 220–300 °C (1 °C min⁻¹). GC and GC–MS conditions for the volatile compounds were as follows: injection temperature = 200 °C, column temperature = 40–300 °C (5 °C min⁻¹) for GC and 30–300 °C (5 °C min^-1) for GC–MS. Compound 6 was purchased from Wako Pure Chemical Industries, Ltd. (Osaka, Japan). Two ambergris samples (NSMT M55020 and NSMT M55019; Supplementary Fig. 7) stored in the National Museum of Nature and Science (Japan) for more than 30 years were used for the analysis of volatile components.

The stems collected after incubation for 0 d, 7 d, 14 d, 21 d and 28 d were collected for determination of dendrobine content. After the stems of each treatment were dried at 55 °C, they were thoroughly mixed with a pestle and mortar and ground into a fine powder. The dendrobine standard and internal standard naphthalene used in the experiment were purchased from Sinopharm Chemical Reagent Co., Ltd. and China Food and Drug Control Institute respectively. The GC analysis samples were prepared in accordance with the Chinese Pharmacopoeia (2020). Chromatography was performed on an Agilent 6890 GC-FID, using an Agilent DB-1 capillary column (0.25 μm × 0.25 mm × 30 m) and nitrogen as the carrier gas.
The experimental sample was repeated at least three times. The samples were analyzed in random order. Each injection of 1 µL for analysis. The parameters and methods of gas chromatography analysis refer to the Chinese Pharmacopoeia (2020). The flame ionization detection was used to extract the components of the total ion chromatogram. The relative correction factor of naphthalene and dendrobine was obtained (f = 0.002734). The linear regression equation y = 0.1176x + 0.0907 (R² = 0.9991) proved that the concentration of dendrobine was linear, and the peak area is in the range of 4.6−23.0 mg·L⁻¹.

The GC–MS analyses of ASH extracts were performed using a Shimadzu QP2010 SE gas chromatography-mass spectrometer (Shimadzu, Kyoto, Japan) equipped with a DB-1 capillary column (25 m in length × 0.32 mm in diameter × 0.52 µm in thickness) (Agilent, USA). Helium was used as the carrier gas at a constant flow rate of 0.5 mL/min. For GC–MS spectral detection, an electron ionization energy method was adopted with a high ionization energy of 70 eV. The injector temperature was set to 250 °C. The temperature of the column was set at 40 °C for 4 min and increased by 10 °C per minute up to 240 °C. Based on a comparison of the retention time (min), peak area, peak height, and mass spectrum of the phytochemicals present in the test samples and the mass spectral library database, we identified the phytochemical contents of the test samples.