Succinic acid-producing biofilms of Actinobacillus succinogenes : reproducibility, stability and productivity
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Date
Authors
Maharaj, Karishma
Bradfield, M.F.A. (Michael Ford Alexander)
Nicol, Willie
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
Continuous anaerobic fermentations were performed
in a biofilm reactor packed with Poraver® beads.
Dilution rates (D) varied between 0.054 and 0.72 h−1, and
D-glucose and CO2 gas were used as carbon substrates.
Steady-state conditions were shown to be repeatable and
independent of the operational history. Production stability
was achieved over periods exceeding 80 h at values of D
below 0.32 h−1. In these situations, steady-state variation
(expressed as fluctuations in NaOH neutralisation flow
rates) exhibited a standard deviation of less than 5 % while
no indication of biofilm deactivation was detected. The
total biomass amount was found to be independent of the
dilution rate with an average dry concentration of 23.8±
2.9 g L−1 obtained for all runs. This suggests that the
attachment area controls the extent of biofilm accumulation.
Specific succinic acid (SA) productivities, based on the
total biomass amount, exhibited a substantial decrease with
decreasing D. An SA volumetric productivity of
10.8 g L−1 h−1 was obtained at D=0.7 h−1—the highest
value reported to date in Actinobacillus succinogenes fermentations.
SA yields on glucose increased with decreasing
D, with a yield of 0.90±0.01 g g−1 obtained at a D of
0.054 h−1. Production of formic acid approached zero with
decreasing D, while the succinic to acetic acid ratio increased
with decreasing D, resulting in an increasing SA
yield on glucose.
Description
Keywords
Actinobacillus succinogenes, Biofilm reactor, Continuous fermentation, Productivity, Stability, Succinic acid
Sustainable Development Goals
Citation
Maharaj, K, Bradfield, MFA & Nicol, W 2014, 'Succinic acid-producing biofilms of Actinobacillus succinogenes : reproducibility, stability and productivity', Applied Microbiology and Biotechnology, vol. 98, no.17, pp. 7379-7386.