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Increased Rhamnolipid Concentration and Productivity Achieved with Advanced Process Design
Author(s) -
Invally Krutika,
Ju LuKwang
Publication year - 2020
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1002/jsde.12457
Subject(s) - rhamnolipid , chemistry , growth rate , productivity , stationary phase , phase (matter) , production rate , fermentation , nitrogen , food science , chromatography , bacteria , mathematics , organic chemistry , biology , process engineering , genetics , geometry , macroeconomics , engineering , economics , pseudomonas aeruginosa
Rhamnolipids are biosurfactants having several applications. A major limitation in rhamnolipid production is low productivity, which decreases significantly during stationary‐phase production. In this study, fermentations were first made with nitrogen‐limited stationary phase. Long‐term rhamnolipid production (up to 505 h) could be maintained with low‐rate N‐source addition but the intermittent cell growth led to lower productivity (q p ), particularly apparent at the highest addition rate. Four fermentations were next made under non‐N‐limited stationary phase without and with N‐source supplementation; q p could be much higher at 24–26 mg g −1 h −1 . Three final fermentations were designed to build the maximum cell concentration to 30 g L −1 in two growth phases where the growth rate in the second phase was regulated by N‐addition to control foaming. Cultures then entered non‐N‐limited stationary phase and were N‐supplemented. At an optimal rate of 15% growth‐N per 24 h to maintain cell activity, a highest rhamnolipid concentration of 120 g L −1 was obtained after 144 h with overall productivity of 839 mg L −1 h −1 .