## 3 Results
### Identification of Lutein of Sphingomonas morindae sp. NBD5 and Sphingopyxis sp. USTB-05  
Under the applied chromatographic conditions, the retention time of standard lutein was at 5.5 min on LC-Q-TOF/MS (Figure S6a). A peak in the extract of _Sphingomonas morindae_ sp. NBD5 also arose at the same retention time (Figure S6b). Furthermore, the scanning profiles from 350 nm to 550 nm between lutein peak and a peak in the extract of _Sphingomonas morindae_ sp. NBD5 at same retention time were almost same each other and the maximum absorbance were all at 446 nm or so (Figure S6). The mass spectral analysis of standard lutein (Figure S7a) and a peak at same retention time in the extract of _Sphingomonas morindae_ sp. NBD5 (Figure S7b) revealed a major ion at _m_/z 568.4289, corresponding to the [M+H]\({}^{+}\) protonated molecular ion, which all accorded with the lutein molecular weight [21; 22; 23]. The _m_/z 568.4289 was selected as the parent ion, and the secondary scan was performed. In the detection of standard lutein and the extract of _Sphingomonas morindae_ sp. NBD5, the parent ion _m_/z 568.4283 was subjected to a collision cracking of 15 eV in the collision cell, where in the main ions were _m_/z 476.3656 [M+H-92]\({}^{+}\), _m_/z 458.3542 [M+H-92-18]\({}^{+}\) and _m_/z 430.3239 [M+H-92-18-28]\({}^{+}\) (Figure S8). Among them, _m_/z 476.3656 is formed when the molecular ion peak loses the carotenoid characteristic group of _m_/z 92 [22]. Corresponding with the data in the report, the molecular formula of _m_/z 476.3656 characteristic ion fragment is C\({}_{33}\)H\({}_{48}\)O\({}_{2}\), which is formed by the loss of C\({}_{7}\)H\({}_{8}\) molecule by the parent ion _m_/z 568.4280 [21], which completely confirmed that lutein could be produced by _Sphingomonas morindae_ sp. NBD5. The streak plate colonies of _Sphingomonas morindae_ sp. NBD5 grew on solid medium at five days. The yellow color of _Sphingomonas morindae_ sp. NBD5 colonies is similar to that of lutein (Figure 5a). In conclusion, genomic annotation, mass spectrometry identification, and appearance comparison showed that strains of _Sphingomonas morindae_ sp. NBD5 produced lutein. Similarly, the genomic annotation and appearance comparison of _Sphingopyxis_ sp. USTB-05 showed that _Sphingopyxis_ sp. USTB-05 produced lutein or zeaxanthin (Figures 4 and 5b). \begin{table}
\begin{tabular}{c c c c c} \hline
**Pathway** & **Genes** & **Coded Protein/Enzyme** & **Catalytic Substrate** & **Catalytic Product** \\ \hline \multirow{6}{*}{
\begin{tabular}{} \end{tabular} } & _crtB_ & 15-cis-phytoene synthase & Geranyl-gearanyl-PP & Prephytoene-PP \\  & _crtE_ & Phytone desaturase & 15-cis-phytoene & All-trans-neuroporene \\  & _crtI_ & Phytone desaturase & Phytonee & Lycopene \\ biosynthesis & _crtQ_ & Phytoe desaturase & 15-cis-phytoene & All-trans-lycopene \\  & _crtL_ & Lycopene \(\beta\)-cyclase & Lycopene & \(\gamma\)-Carotene \\  & _crtR_ & \(\beta\)-carotene 3-hydroxyase & \(\beta\)-Carotene & Zeaaxanthin \\ \hline \end{tabular}  
* The bold fonts indicate that these genes are only present in _Sphingomonas morindae_ sp. NBD5 genome, but not in _Sphingopyxis_ sp. USTB-05.
* The bold fonts indicate that these genes are only present in _Sphingopyxis_ sp. USTB-05 genome, but not in _Sphingopyxis_ sp. USTB-05 showed that _Sphingopyxis_ sp. USTB-05 produced lutein (Figures 4 and 5b).  
\end{table} 
Table 2: _Cont._Figure 4: The proposed biosynthetic pathway of MP of _Sphingomonas morindae_ sp. NBD5 and _Sphingopyxis_ sp. USTB-05.