Given the role of
bacteria in the supply of exogenous vitamins (Croft et al., 2005,
2006; Kazamia et al., 2012), the axenic nature of cultures was
important and was confirmed via inspection of cultures using
DNA-stained (DAPI) cell counts. Cultures were grown in sterilized,
1-L PyrexTM Erlenmeyer flasks and maintained at 21 8C on a 14:10
light:dark cycle in an incubator under 100 mmol quanta m2 s1.
Cultures were grown under vitamin B12 replete and depleted
conditions with vitamin concentrations in depleted cultures
diluted via successive transfers (Tang et al., 2010).