The high leaching efficiency observed from cultures preserved
using cold storage may also be explained by differing rates of cell
growth recovery (Fig. 2). Cold storage slows, but does not stop cell
metabolism, allowing more efficient growth recovery in comparison
to cryopreservation or liquid-drying. Failure to achieve a
growth recovery after revival from cryopreservation may have
resulted in longer lag phases and delays in leaching of up to
35 days in similar studies of bioleaching extremophiles (Zeng
et al., 2010). Thus, consideration of culture growth recovery time
after revival from preservation before application for research,
commercial or industrial applications is recommended to ensure
cultures have consistent and efficient rates of growth.