Improving fermentation consistency through better inoculum preparation

Substantial losses occur in the fermentation industry each year due to variability in yields and productivity. As the first stage in the process, inoculum consistency, in terms of size and quality, is clearly important. Yet, despite this, most inoculum development processes involve at least one highly variable transfer step, usually by wire loop, from a culture grown on a solid (agar) substrate. It is likely, then, that at least some of the variability in the production process can be attributed to a poorly controlled initial inoculation process.Experiments to determine the inherent variability of the conventional loop transfer technique showed a 12-fold variation in inoculum size. Although this can be improved by adopting a more rigid protocol, consistency is still poor. A simple alternative system, based on liquid transfers, leads to substantial improvements in the reproducibility of inoculum size and quality.