Batch, semi-continuous,
and continuous culture systems
Because microalgal culture produces high concentrations
of cells, most laboratories require only small
volumes of algae for food. These can be cultured in 4-L
containers or 20-L carboys using “batch” culture protocols.
Commercial hatcheries, which require much larger
volumes of algae, often use semi-continuous or continuous
culture systems.
Batch cultures are inoculated with the desired species
that will grow rapidly under optimal conditions until the
rate of cell division begins to decline, indicating the transition
from the exponential phase to the stationary phase.
At that point, the culture is completely harvested and the
container is washed, refilled (with sterilized, enriched medium),
and inoculated to begin a new culture. Batch culture
is generally used for delicate species or for rapidly growing
diatoms. Although batch culture is considered the least
efficient method of production, it is predictable, and contamination
is less likely than in semi-continuous cultures