**Appendix A**

**Figure A1.** Iron chelating CAS assay after 5 days' growth. Zones of activity are separated into 4 groups based on range of colour change, as indicated in red by each strain name.

**Figure A2.** Variant metal(loid) CAS assay after 5 days' growth for strains P4 and KR99. Growth on RO without CAS was compared to those CAS plates supplemented with Mg, V, Mn, Fe, Co, Ni, Cu, Zn, Se, or Te.


**Table A1.** Freshwater and saline AAP chosen for siderophore testing.


**Table A2.** Meromictic lake and biological soil crust AAP chosen for siderophore testing.
