FIG. 2.

(A) Demethylation of SECO by the isolated strain P. productus SECO-Mt75m3. Incubation took place at 37°C in Mt-6 broth. Samples were collected at the times indicated on the chromatograms. Supernatants were analyzed by HPLC as described previously. The demethylation of SECO led to the formation of compound B (5.8 min) via compound A (6.7 min). The molecular weight of A was 348 g mol⁻¹, as determined by mass spectrometry. This weight corresponds to the molecular weight of SECO with one methyl group removed. Compound B was identified as 2,3-bis(3,4-dihydroxybenzyl)butene-1,4-diol by comparison with the retention time and spectrum of the standard. It lacks the two methyl groups of SECO. (B) Formation of ED from SECO by coculture of the isolated strains P. productus SECO-Mt75m3 and E. lenta SECO-Mt75m2. Incubation took place at 37°C in Mt-75 broth. The molecular weight of C (7.9 min) was 332 g mol⁻¹, as determined by mass spectrometry. This weight corresponds to the molecular weight of SECO with one methyl group and one hydroxyl group removed.