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Evaluation of productive biofilms for continuous lactic acid production
Author(s) -
Cuny Laure,
Pfaff Daniel,
Luther Jonas,
Ranzinger Florian,
Ödman Peter,
Gescher Johannes,
Guthausen Gisela,
Horn Harald,
HilleReichel Andrea
Publication year - 2019
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.27080
Subject(s) - biofilm , lactic acid , continuous flow , food science , fermentation , bioreactor , bacteria , chemistry , yield (engineering) , biotransformation , lactobacillus , microbiology and biotechnology , productivity , biochemistry , biology , materials science , organic chemistry , biochemical engineering , genetics , macroeconomics , economics , engineering , metallurgy , enzyme
In white biotechnology research, the putative superiority of productive biofilms to conventional biotransformation processes based on planktonic cultures has been increasingly discussed in recent years. In the present study, we chose lactic acid production as a model application to evaluate biofilm potential. A pure culture of Lactobacillus bacteria was grown in a tubular biofilm reactor. The biofilm system was cultivated monoseptically in a continuous mode for more than 3 weeks. The higher cell densities that could be obtained in the continuous biofilm system compared with the planktonic culture led to a significantly increased space‐time yield. The productivity reached 80% of the maximum value 10 days after start‐up and no subsequent decline was observed, confirming the suitability of the system for long‐term fermentation. The analysis of biofilm performance revealed that productivity increases with the flow velocity. This is explained by the reduced retention time of the liquid phase in the reactor, and, thus, a minor pH drop caused by the released lactic acid. At low flow velocities, the pH drops to a value where growth and production are significantly inhibited. The biofilm was visualized by magnetic resonance imaging to analyze biofilm thickness. To deepen the understanding of the biofilm system, we used a simple model for cell growth and lactic acid production.