Original Research Paper

Biotechnology Letters

, Volume 32, Issue 10, pp 1405-1412

First online:

An investigation into the preservation of microbial cell banks for α-amylase production during 5 l fed-batch Bacillus licheniformis fermentations

  • Nichola H. HancocksAffiliated withSchool of Chemical Engineering, University of Birmingham
  • , Colin R. ThomasAffiliated withSchool of Chemical Engineering, University of Birmingham
  • , Stuart M. StocksAffiliated withNovozymes A/S
  • , Christopher J. HewittAffiliated withDepartment of Chemical Engineering, Centre for Biological Engineering, Loughborough University Email author 

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Fluorescent staining techniques were used for a systematic examination of methods used to cryopreserve microbial cell banks. The aim of cryopreservation here is to ensure subsequent reproducible fermentation performance rather than just post thaw viability. Bacillus licheniformis cell physiology post-thaw is dependent on the cryopreservant (either Tween 80, glycerol or dimethyl sulphoxide) and whilst this had a profound effect on the length of the lag phase, during subsequent 5 l fed-batch fermentations, it had little effect on maximum specific growth rate, final biomass concentration or α-amylase activity. Tween 80 not only protected the cells during freezing but also helped them recover post-thaw resulting in shorter process times.


Bacteria Flow cytometry Membrane potential Membrane integrity Cryopreservation Fermentation Bacillus licheniformis