2.5 Metabolite analysis
After centrifuging the sample, the supernatant was obtained through a
0.22 μM filter and then analyzed. All metabolites were analyzed by HPLC
equipment (Agilent, Waldbronn, Germany) with the HPX-87H column
(Bio-Rad, CA, USA). The different detectors (refractive index and
ultraviolet) were used at the same time and the ultraviolet wavelength
was controlled at 210 nm. The
30 mM H2SO4 at 0.3 mL/min at 42 °C was
used in the detect process(Babu et al.,
2015; Zhao, Li, & Deng, 2018).