Biotechnology Letters

, Volume 32, Issue 10, pp 1405–1412 | Cite as

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

  • Nichola H. Hancocks
  • Colin R. Thomas
  • Stuart M. Stocks
  • Christopher J. Hewitt
Original Research Paper


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 

List of symbols


Feed rate (l h−1)


Substrate concentration in the feed solution (g l−1)


Desired specific growth rate (h−1)


Maximum biomass yield with a limiting substrate (g/g)


Initial amount of cells at the start of feeding (g)


Maintenance coefficient (gg−1 h−1)


Time after feeding commences (h)


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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Nichola H. Hancocks
    • 1
  • Colin R. Thomas
    • 1
  • Stuart M. Stocks
    • 2
  • Christopher J. Hewitt
    • 3
  1. 1.School of Chemical EngineeringUniversity of BirminghamBirminghamUK
  2. 2.Novozymes A/SBagsværdDenmark
  3. 3.Department of Chemical Engineering, Centre for Biological EngineeringLoughborough UniversityLoughboroughUK

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