Figure 7.

Bioassays with O. tauri RCC745 indicate B1 precursors are more abundant relative to B1 in coastal seawater from the northwestern Mediterranean Sea (SOLA site). Wild-type (Wt) and ΔThiM O. tauri RCC745 (ΔThiM) cells deprived of B1 for 7 days were inoculated (10 cells ml⁻¹) in filter-sterilized SOLA seawater from 3 m. After 7 days, maximum yields of the wild-type were significantly higher than those of the ΔThiM mutant; in contrast, yields of the wild-type and ΔThiM mutant grown on SOLA water supplemented with B1 were identical. The means and s.d. of biological triplicates are shown. Yields from negative control cultures (-Control), cells added to vitamin deplete medium, are also shown.