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Enhanced rhamnolipid production by P seudomonas aeruginosa USM ‐ AR 2 via fed‐batch cultivation based on maximum substrate uptake rate
Author(s) -
Md Noh N.A.,
Mohd Salleh S.,
Yahya A.R.M.
Publication year - 2014
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12236
Subject(s) - rhamnolipid , substrate (aquarium) , biomass (ecology) , batch reactor , yield (engineering) , fed batch culture , fermentation , bioreactor , batch processing , chemistry , food science , chromatography , pulp and paper industry , pseudomonas aeruginosa , materials science , biology , bacteria , biochemistry , catalysis , organic chemistry , agronomy , ecology , genetics , computer science , metallurgy , programming language , engineering
A fed‐batch strategy was established based on the maximum substrate uptake rate ( MSUR ) of P seudomonas aeruginosa USM ‐ AR 2 grown in diesel to produce rhamnolipid. This strategy matches the substrate feed rates with the substrate demand based on the real‐time measurements of dissolved oxygen ( DO ). The MSUR was estimated by determining the time required for consumption of a known amount of diesel. The MSUR trend paralleled the biomass profile of Ps. aeruginosa USM ‐ AR 2, where the MSUR increased throughout the exponential phase indicating active substrate utilization and then decreased when cells entered stationary phase. Rhamnolipid yield on diesel was enhanced from 0·047 (g/g) in batch to 0·110 (g/g) in pulse‐pause fed‐batch and 0·123 (g/g) in MSUR fed‐batch. Rhamnolipid yield on biomass was also improved from 0·421 (g/g) in batch, 3·098 (g/g) in pulse‐pause fed‐batch to 3·471 (g/g) using MSUR ‐based strategy. Volumetric productivity increased from 0·029 g l −1 h −1 in batch, 0·054 g l −1 h −1 in pulse‐pause fed‐batch to 0·076 g l −1 h −1 in MSUR fed‐batch. Significance and Impact of the Study This study highlights the significance of an effective fed‐batch strategy for rhamnolipid production in a submerged fermentation using a water‐immiscible substrate, based on maximum substrate uptake rate. The impact of this strategy ensured that the substrate was supplied at the rate matching the maximum substrate utilization by the cells without excess feeding, leading to increased rhamnolipid production, yield and productivity.