Using iron magnetism to select for genetic variations in unicellular organisms
Nishida and Silver (2012) report, that model organism Saccharomyces cerevisiae becomes paramagnetic, when grown on iron citrate. Magnetism is enhanced upon a shift of cytoplasmatic redox state towards a more oxidized state, upon addition of human ferritin iron chelator and upon deletion of vacuolar iron importer.
Magnetism is proportional to Tco89 activity, which obviously shifts the cellular redox state towards a more oxidized state. Therefore oxidative stress is also expected to increase magnetism. Mitochondrial activity is known to excert oxidative stress, therefore magnetism can be used to separate metabolically active from inactive cells.
Such a procedure provides the advantage, that no antibiotics need to be applied. Mutant selection can therefore be carried out, without the need for common methods of molecular biology, allowing for culturing of genetic variations outside a genetics lab.