Abstract:
:The growth and product formation of a Savinase-producing Bacillus clausii were investigated in high-cell-density fed-batch cultivations with both linear and exponential feed profiles. The highest specific productivity of Savinase was observed shortly after the end of the initial batch phase for all feed profiles applied and, in addition, there was a time-dependent decrease in specific productivity. The specific glucose uptake rate increased with time for constant specific growth rate indicating that the maintenance requirements increased with time, possibly due to a decreasing K(+) concentration. The physiological state of the cells was monitored during the cultivations using a flow cytometry assay based on the permeability of the cell membrane to propidium iodide. In the latter parts of the fed-batch cultures with a linear feed profile, a large portion of the cell population was found to have a permeable membrane, indicating a large percentage of dead cells. By assuming that only cells with a nonpermeable membrane contributed to growth and product formation, the physiological properties of this subpopulation were calculated.
journal_name
Biotechnol Bioengjournal_title
Biotechnology and bioengineeringauthors
Christiansen T,Michaelsen S,Wümpelmann M,Nielsen Jdoi
10.1002/bit.10675subject
Has Abstractpub_date
2003-08-05 00:00:00pages
344-52issue
3eissn
0006-3592issn
1097-0290journal_volume
83pub_type
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journal_title:Biotechnology and bioengineering
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