Figure 1
Phosphorus starvation induces alkaline phosphatase activity, plcP expression (a–c) and membrane lipid remodelling (d–f) in representative marine bacterial heterotrophs. RT-PCR results show plcP is transcribed under P-deplete conditions and repressed shortly (2 h) after P is added back to the media (P re-fed). rplU or 16S rRNA transcript levels were used as control for cDNA synthesis. Line graph (g) shows the accumulation of DGTS in Phaeobacter sp. MED193 over time in P-deplete (solid line) but not in P-replete (dashed line) media. DGTS synthesis is observed in wild type (Wt) but not in a plcP deletion mutant (ΔplcP) (h). Complementation with plcP from MED193 (ΔplcPMED193) or from SAR11 (ΔplcPSAR11) is sufficient to restore DGTS synthesis. Error bars represent the s.d. of three independent replicates. phoX: Alkaline phosphatase PhoX gene, DNA: PCR positive control, NT: no template control, APA: alkaline phosphatase activity, PA: phosphatidic acid, OL: ornithine lipid, GL: glutamine lipid, BLL: an uncharacterized betaine lipid, AAL2, AAL3, AAL4: uncharacterized aminolipids, OL-OH: a hydroxylated ornithine lipid.
