Different feeding strategy for the production of biosurfactant from Pseudomonas aeruginosa USM AR2 in modified bioreactor

Salwa, M S; Asshifa, M.N. Nur; Amirul, Al-Ashraf Abdullah; Yahya, Ahmad Shukri

doi:10.1007/s12257-009-0086-z

Cited by 13 publications

(8 citation statements)

References 23 publications

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“…A stirred-tank bioreactor was retrofitted with a foam collector on its gas outlet. Foam, containing biosurfactants, was allowed to flow out of the bioreactor from the air outlet and left to collapse into liquid in a separate vessel, and pumped back into the fermentation vessel (Salwa et al 2010). The modified bioreactor was able to address the foaming problem without the addition of any antifoam agent.…”

Section: Methodsmentioning

confidence: 99%

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Enhanced rhamnolipid production by Pseudomonas aeruginosa USM-AR2 via fed-batch cultivation based on maximum substrate uptake rate

Noh

Salleh

Yahya

2014

Lett Appl Microbiol

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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. AbstractA fed-batch strategy was established based on the maximum substrate uptake rate (MSUR) of Pseudomonas aeruginosa USM-AR2 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-AR2, 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 0Á047 (g/g) in batch to 0Á110 (g/g) in pulse-pause fed-batch and 0Á123 (g/g) in MSUR fed-batch. Rhamnolipid yield on biomass was also improved from 0Á421 (g/g) in batch, 3Á098 (g/g) in pulse-pause fed-batch to 3Á471 (g/g) using MSUR-based strategy. Volumetric productivity increased from 0Á029 g l À1 h À1 in batch, 0Á054 g l À1 h À1 in pulse-pause fed-batch to 0Á076 g l À1 h À1 in MSUR fed-batch.

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Section: Methodsmentioning

confidence: 99%

“…Typically, foam production in Ps. aeruginosa USM-AR2 culture is extremely quick and severe, making antifoam addition ineffective (Nur Asshifa 2009;Salwa et al 2010).…”

Section: Methodsmentioning

confidence: 99%

Enhanced rhamnolipid production by Pseudomonas aeruginosa USM-AR2 via fed-batch cultivation based on maximum substrate uptake rate

Noh

Salleh

Yahya

2014

Lett Appl Microbiol

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“…Similar to other fermentations where the secreted metabolites with high surface activity (like biosurfactant, protein, etc.) cause severe foaming under aeration [18], the biosurfactant rhamnolipid has been accepted as the major component dominating the severe foaming during fermentation [19][20][21][22]. However, a recent study by Sodagari and Ju claimed that the hydrophobic cell could contribute more to the foaming than rhamnolipid itself in rhamnolipid fermentation [17].…”

Section: Introductionmentioning

confidence: 99%

Mechanism Study on the Severe Foaming of Rhamnolipid in Fermentation

Long

Sha

Meng

et al. 2016

J Surfact & Detergents

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Although the biosurfactant rhamnolipid has been previously characterized as having low foam ability, its fermentation is largely impeded by severe foaming. Hence, the investigation of this paradox is critically important for improving the mass production of rhamnolipid. Unexpectedly, the hydrophobic cell, instead of rhamnolipid, has been claimed to explain such severe foaming in rhamnolipid fermentation. This study tried to systematically investigate the severe foaming in fermentation, aiming to propose an effective strategy for foam control. The overflowing foam sustained a super high stability in terms of half‐time for over 30 min. The major product of rhamnolipid largely contributed to the severe foaming in the fermentation process whereas other products like cells elicited much more limited effects. Furthermore, the foam stability of the fermentation broth increased with rhamnolipid concentration and noticeably increased with agitation speed. In the classic Bikerman foam test system without stirring, rhamnolipid showed foam stability as low as Tween 20 which is well known for its poor foam stability. However, in a stirring Bikerman system, rhamnolipid exhibited a foam stability almost as high as sodium dodecyl sulfate (SDS) at 10 g/L and even surpassed SDS at a higher concentration of 20 g/L. Hence, the extraordinarily increased foam stability of rhamnolipid with both agitation and concentration could explain the severe foaming at its late‐stage fermentation when rhamnolipid‐rich solution is mechanically agitated.

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“…Biosurfactants are surface‐active molecules produced by microorganisms and characterized by lower toxicity, higher biodegradability and greater environmental compatibility compared with petroleum‐based surfactants 1, 2. Rhamnolipids produced by Pseudomonas aeruginosa are one of the most extensively studied biosurfactants,3 with one or two rhamnose molecules linked to fatty acids 4.…”

Section: Introductionmentioning

confidence: 99%

“…Normally, high aeration under intense agitation benefits microbial growth and production in aerobic fermentation by providing sufficient oxygen 1. However, they generate a severe foaming problem, particularly in the fermentation of highly foaming biosurfactants 2. The severe foaming inhibits cell growth by reducing the bioavailability of substrates as well as the transfer efficiency of oxygen into the liquid medium, and decreased the working efficiency of the bioreactor 5.…”

Section: Introductionmentioning

confidence: 99%