Foam and Its Mitigation in Fermentation Systems

Junker, Beth

doi:10.1021/bp070032r

Cited by 35 publications

(34 citation statements)

References 84 publications

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“…It had been reported that hydrophobic cells could concentrate at the gas/liquid interface and stabilize the foams [25]. In our previous study, the relative hydrophobicity of various bacterial cells was measured by the partitioning of cells to the water-hexadecane interface [24].…”

Section: Discussionmentioning

confidence: 99%

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Cells Were a More Important Foaming Factor than Free Rhamnolipids in Fermentation of Pseudomonasaeruginosa E03‐40 for High Rhamnolipid Production

Sodagari

2013

J Surfact & Detergents

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Rhamnolipids are among the best‐known biosurfactants. Severe foaming occurs in aerobic rhamnolipid fermentation and negatively affects operation and economics of the biosurfactant production. In this study the foaming properties were examined with samples taken along a Pseudomonas aeruginosa fermentation that produced 55 g l−1 rhamnolipids with a maximum volumetric productivity of 0.080 g l−1 h−1 and a maximum specific productivity of 0.013 g g−1 h−1. For a better understanding of the process, the broth samples were also centrifuged to prepare cell‐free supernatants and cell suspensions in water, and all samples were evaluated under fixed foaming conditions. In addition to the time profiles of foam rise, the initial foaming rates and maximum foam volumes were determined. Contrary to the general assumption, the cells, not rhamnolipids, were the main foaming agents in the fermentation. Soluble components including rhamnolipids had secondary roles. Supernatant foaming was higher after the culture entered the rhamnolipid‐producing stationary phase; however, the foaming appeared to decrease with increasing rhamnolipid concentrations at high concentrations (>15 g l−1). The pH effects on foaming of broths, supernatants, and cell suspensions were also studied. Broth foaming was 55 and 80 % less at pH 5.5 and 5.0, respectively, compared to that at pH 6.5. Cell growth and rhamnolipid production at lower pH should be included in future studies. In addition, strain selection or genetic engineering and medium modification to reduce cell hydrophobicity are suggested as useful strategies to address the foaming issue of rhamnolipid fermentation.

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Section: Discussionmentioning

confidence: 99%

“…Soybean oil content is expected to affect foaming. It is common to use oils to decrease the foam formation in fermentation processes [25,26]. According to Rols and Goma, the oils would increase the gas bubble size and make the foam less stable [27].…”

Section: Effects Of Soybean Oil Contentmentioning

confidence: 99%

Cells Were a More Important Foaming Factor than Free Rhamnolipids in Fermentation of Pseudomonasaeruginosa E03‐40 for High Rhamnolipid Production

Sodagari

2013

J Surfact & Detergents

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“…Foam stabilization due to presence of hydrophobic particles such as Norcadia cell solids has also been reported (Jenkins et al, 1993). Several foam mitigation strategies have been reported in literature and are clearly applicable to improve the productivity of our process, which we envision pursuing in the future (Junker, 2007).…”

Section: Discussionmentioning

confidence: 99%

L‐Tyrosine production by recombinant Escherichia coli: Fermentation optimization and recovery

Patnaik

Zolandz

Green

et al. 2008

Biotech & Bioengineering

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L-Tyrosine (L-tyr) overproducing Escherichia coli strain derived from an L-phenylalanine (L-phe) overproducing strain is characterized in 10 L and 200 L scale fermentations. Deletion of the chromosomal region encoding for the pheA gene, chorismate mutase/prephenate dehydratase, its leader peptide (pheL) and its associated promoter resulted in significant increase in L-tyr production (Olson et al., 2007. Appl Microbiol Biotechnol 74(5):1031-1040). Further increase in titer was achieved by overexpressing tyrA, encoding chorismate mutase/prephenate dehydrogenase, from a strong non-native trc promoter (Olson et al., 2007. Appl Microbiol Biotechnol 74(5):1031-1040). Fermentation optimization studies include media component selection; glucose feed optimization, antifoam agent selection, and understanding fermentation parameters affecting foaming. Generational stability of the strain was evaluated along with rate, titer, and yield of tyrosine formation from glucose. L-tyr titer of 55 g/L in 48 h was demonstrated in 200 L batches, is the highest titer published till date. We have also evaluated two primary separations schemes to isolate and purify L-tyr from the fermentation broth. Physical separation of L-tyr crystals from biomass using a decanter type centrifuge, based on the density difference between the solids, is compared and contrasted with a strategy where L-tyr is first dissolved at pH 11.5 and then acid precipitated from clarified supernatants following removal of biomass using membrane filtration. L-tyr product purity of 98% with yields ranging from 90% to 95% is demonstrated.

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“…[1][2][3][4][5] These factors include solution properties such as medium composition, cell density, cell viability, cell growth, and titer, in addition to bioreactor operating conditions such as gas flow rate, sparger orifice size, agitation rate, temperature, and vessel geometry. 3 While some foam can be tolerated, excessive foam accumulation can significantly lower operational efficiency and overall protein production. Uncontrolled foam proliferation has the potential to reduce the maximum working volume of culture, 1,3 deposit medium components and/or product on non-wetted surfaces, 3 hinder gas mass transfer, 1,3,5 and clog vent filters.…”

Section: Introductionmentioning

confidence: 99%

“…6 Surface-active antifoam globules enter foam films and cause film rupture via several possible mechanisms detailed elsewhere. 3,6 Raw material suppliers offer various types of water-dilutable, emulsion-based antifoams. 3 In biopharmaceutical processes, it is important to consider cost, usage requirements, antifoam efficiency, solubility in cell culture fluid, chemical properties, toxicity, mass transfer effects, downstream clearance, assay compatibility or interference (e.g., with pH or dissolved oxygen (DO) sensors), and sterilization options.…”

Section: Introductionmentioning

confidence: 99%

Endotoxin inactivation via steam‐heat treatment in dilute simethicone emulsions used in biopharmaceutical processes

Britt

Galvin

Gammell

et al. 2014

Biotechnology Progress

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Simethicone emulsion is used to regulate foaming in cell culture operations in biopharmaceutical processes. It is also a potential source of endotoxin contamination. The inactivation of endotoxins in dilute simethicone emulsions was assessed as a function of time at different steam temperatures using a Limulus amebocyte lysate kinetic chromogenic technique. Endotoxin inactivation from steam-heat treatment was fit to a four-parameter double exponential decay model, which indicated that endotoxin inactivation was biphasic, consisting of fast and slow regimes. In the fast regime, temperature-related effects were dominant. Transitioning into the slow regime, the observed temperature dependence diminished, and concentration-related effects became increasingly significant. The change in the Gibbs free energy moving through the transition state indicated that a large energy barrier must be overcome for endotoxin inactivation to occur. The corresponding Arrhenius pre-exponential factor was >>10(12) s(-1) suggesting that endotoxins in aqueous solution exist as aggregates. The disorder associated with the endotoxin inactivation reaction pathway was assessed via the change in entropy moving through the transition state. This quantity was positive indicating that endotoxin inactivation may result from hydrolysis of individual endotoxin molecules, which perturbs the conformation of endotoxin aggregates, thereby modulating the biological activity observed. Steam-heat treatment decreased endotoxin levels by 1-2 logarithm (log) reduction (LRV), which may be practically relevant depending on incoming raw material endotoxin levels. Antifoam efficiency and cell culture performance were negligibly impacted following steam-heat treatment. The results from this study show that steam-heat treatment is a viable endotoxin control strategy that can be implemented to support large-scale biopharmaceutical manufacturing.

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Foam and Its Mitigation in Fermentation Systems

Cited by 35 publications

References 84 publications

Cells Were a More Important Foaming Factor than Free Rhamnolipids in Fermentation of Pseudomonasaeruginosa E03‐40 for High Rhamnolipid Production

Cells Were a More Important Foaming Factor than Free Rhamnolipids in Fermentation of Pseudomonasaeruginosa E03‐40 for High Rhamnolipid Production

L‐Tyrosine production by recombinant Escherichia coli: Fermentation optimization and recovery

Endotoxin inactivation via steam‐heat treatment in dilute simethicone emulsions used in biopharmaceutical processes

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