Fig. 2

Optimization of MBE production. E. coli RQ1 derivative strains harboring indicated plasmid(s) were grown in LB and, when culture reached OD₆₀₀ ~ 1 induction was carried out by the addition of 0.5-mM IPTG and 0.2 % l-Ara. Immediately after induction, cultures were supplemented with 20-mM propionate, 2-mM oleate, and 1-mM n-octanol, and were incubated at 22 °C for 24 h. After that, cells were harvested and total lipid were extracted and further processed as described in “Methods”. a MBE accumulation in response to variations in the gene expression system. b MBE production in RQ1/pMB07 derivatives strains where different genes were knocked out. As it is mentioned in the main text and described in “Methods”: RQ3 = RQ1 Δsbm; pMB20 = pCA30:T7-accA2-pccE-pccB; RQ4 = RQ1 ΔfadD; RQ5 = RQ1 ΔfadE. c MBE titers for RQ5/pMB07 cells containing indicated plasmids and expressing individual extra copies of papA5 (pMB04) or fadD28 (pMB05). Error bars represent the SD of three experiments conducted by triplicate. Stars mean significant differences respect to empty plasmid control strain (p < 0.05)