Inoculums expansion

Unit operations for biological products obtained from fermentation or cell culture can largely be subdivided into four parts medium preparation, inoculums expansion, bioreactor, and harvest operations. 

One consideration to bear in mind during the design of inoculums expansion is to demonstrate the genetic stability of the cell line beyond the expected number of generations required to operate at large-scale. This is usually accomplished by conducting measurements of product expression and genetic markers in cells from an extended cell bank (ECB). 

For the cultivation of animal cells, inoculum expansions have traditionally been conducted in T-flasks, shake flasks, spinner flasks, or roller bottles. Typi-... 

Cryotube Expansion in stationary flasks Propagation in stirred flasks Inoculum bioreactor Production bioreactor... 

Preparation of inoculum by the expansion of mycelial mass on enriched agar media and then on grain. Implantation of grain spawn into composted and uncomposted substrates or the use of grain as a fruiting substrate. 

The use of perfusion bioreactors, in which the medium is pumped through the culture vessel, has also been reported (Oh et al., 2005) for the expansion of mouse ESC lines on Petriperm (a Petri dish with a gas-permeable base). The cell densities obtained were 64-fold greater compared to Petri dish controls which only originate a nine-fold increase compared to the initial inoculum, over 6 days. The mESCs that were expanded retained pluripotency markers, had the ability to form derivatives of the three embryonic germ layers in teratomas, and maintained karyotypic stability. Perfusion cultures with cell retention ensure homogeneity of nutrient supplementation, inhibition of waste accumulation, and improved process reproducibility (Thomson, 2007). However, these cultures are still at a small-scale. 

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