Abstract
Carbon balancing of microbial fermentations is a valuable tool for the
evaluation of the process performance and to identify the presence of
undesired by-products. In this study, we demonstrate the relevance of
total carbon (TC) analysis for carbon balancing in fermentations with
the wild-type of Corynebacterium glutamicum by (i) quantifying
significant amounts of dissolved inorganic carbonic species (TIC) in the
culture medium and (ii) determining the effective (mass) carbon content
of the biomass fraction (M-C,M-X). In principle, TC based carbon
balancing yielded at fully matching carbon balances. Thus, the
application of our TC approach for the accurate detection of TIC and
M-C,M-X increased the total carbon recovery in standard batch
fermentations with C. glutamicum on glucose from about 76\% to carbon
closures of 94-100\% in contrast to conventional approaches. Besides,
the origin of the missing 6\%-gap could be attributed to incomplete
quantification of all carbon sources in the liquid phase. To conclude
this study, the concept of TC-based balancing was transferred to an
L-lysine production process, successfully quantifying relevant system
carbon fractions, which resulted in matched carbon recoveries. (C) 2014
Elsevier B.V. All rights reserved.
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