TABLE 1.
Analysis of carotenoids accumulated in E. coli transformants carrying various combinations of crt genes from E. uredovora and Bradyrhizobium sp. strain ORS278a
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E. coli host strain characteristics
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E. coli transformant characteristics after complementation
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|---|---|---|---|
| Plasmid (crt genes of E. uredovora carried) | Carotenoid accumulatedc | Plasmid introducedd (crt genes of ORS278 carried) | Carotenoid accumulatedef |
| None | −g | pSTM73 (crtE crtY crtI crtB crtW) | − |
| None | − | pSTM78 (crtE crtY crtI crtB crtW) | − |
| pACCRT-Eb (crtE) | GGPP | pSTM78 (crtE crtY crtI crtB crtW) | Canthaxanthin (100%) [95.4] |
| pSTM420 (crtI crtB crtY) | − | pSTM462 (crtE) | β-Carotene (98%), nich (2%) |
| pACCRT-Eb (crtE) | GGPP | pSTM107 (crtI crtB) | Lycopene (100%) |
| pACCRT-EBb (crtE crtB) | Phytoene | pSTM107 (crtI crtB) | Lycopene (100%) |
| pACCRT-EIBb (crtE crtI crtB) | Lycopene | pSTM108 (crtY) | β-Carotene (100%) |
| pACCRT-EIBYb (crtE crtI crtB crtY) | β-Carotene | pSTM51 (crtW) | Canthaxanthin (90%) [800], echinenone (2%), nic (8%) |
Transformants were grown in Luria-Bertani medium for 36 h in the presence of ampicillin (50 μg/ml), chloramphenicol (30 μg/ml), and 0.125 mM isopropyl-1-thio-β-d-galactopyranoside. The carotenoids were extracted according to the method of Lorquin et al. (12).
The plasmids used were described by Misawa et al. (15). Plasmid pSTM420 was obtained after deletion by SalI digestion of the crtE gene from the plasmid pACCRT-EIBY.
The carotenoids found in E. coli host strains are in accordance with the findings of Misawa et al. (15).
Details on insertion of the various constructed plasmids are presented in Fig. 2.
The percentage of the accumulated carotenoid of the total carotenoid content is indicated in parentheses.
In square brackets, total (cis plus trans) canthaxanthin level is indicated in micrograms per gram of dry cell weight.
−, carotenoids not detected.
nic, nonidentified compound.