Effect of antifoam agents on the medium and microbial cell properties and process performance in small and large reactors

Koch, Volker; Rüffer, H. M.; Schügerl, K.; Innertsberger, Ernst; Menzel, Hartmut; Weis, Johan Ek

doi:10.1016/0032-9592(94)00029-8

Cited by 32 publications

(22 citation statements)

References 22 publications

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“…Improved antifoam efficiency will contribute to fermentation productivity and will ease downstream processing. Improved longevity of antifoam may reduce the need for repeated dosing of antifoam often needed during the later stages of fermentation [11].…”

Section: Introductionmentioning

confidence: 99%

Silicone antifoam performance enhancement by nonionic surfactants in potato medium

Christiano

Fey

2003

J IND MICROBIOL BIOTECHNOL

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The ability of a silicone antifoam to retard foaming in a liquor prepared from potatoes is enhanced by the addition of ethoxylated nonionic surfactants. The enhancement is non-linear for surfactant concentration, with all 12 surfactants tested possessing a concentration at which foam heights strongly diminish, referred to as the surfactant critical antifoaming concentration (SCAFC). SCAFCs vary between surfactants, with lower values indicating better mass efficiency of antifoaming enhancement. SCAFCs decrease with degree of ethoxylation and decrease with the hydrophilic-lipophilic balance for ethoxylated nonionic surfactants. Surfactant addition produces a mixed water-surface layer containing surfactant and surface-active components in the potato medium. Surface tension reduction does not correlate well with antifoam performance enhancement. A model is proposed where surfactant adsorption promotes desorption of surface-active potato medium components from the water surface. At the SCAFC, desorption is not complete, yet the rate of bubble rupture is sufficiently enhanced to provide excellent foam control.

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Section: Introductionmentioning

confidence: 99%

Silicone antifoam performance enhancement by nonionic surfactants in potato medium

Christiano

Fey

2003

J IND MICROBIOL BIOTECHNOL

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“…It is necessary to operate bioreactors with an excess headspace and to suppress foam by the addition of chemical antifoams. This raises the costs of the bioprocess and lowers the productivity of the system due to reduced oxygen‐transfer rates and possible adverse effects on cell physiology 12…”

Section: Introductionmentioning

confidence: 99%

Continuous rhamnolipid production with integrated product removal by foam fractionation and magnetic separation of immobilized Pseudomonas aeruginosa

Heyd

Franzreb

Berensmeier

2011

Biotechnology Progress

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Increasing interest in biological surfactants has led to intensified research directed at more cost-efficient production of biosurfactants, relative to traditional surface-active components based on petrochemical feedstocks. This publication will focus on a new integrated process for continuous rhamnolipid (RL) production. RL was synthesized by Pseudomonas aeruginosa DSM 2874 and was continuously removed in situ by foam fractionation. To prevent loss of the biocatalyst through foaming, bacteria were entrapped in magnetic alginate beads. Immobilizates were retained from the foam by high-gradient magnetic separation and back-flushed in the bioreactor at constant intervals. It was demonstrated that continuous RL production in a 10-L bioreactor over several cycles with intermediate growth periods is feasible. Complete separation of RLs from the production medium with an average enrichment ratio of 15 in the collapsed foam was demonstrated, yielding a final RL amount of 70 g after four production cycles.

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“…More precisely, a decrease of biomass concentration has been observed after 32 h and can be related to the removal of microbial cells from the medium and their accumulation in the foam phase. As stated above, it is generally recognized that physical defoaming methods are more suited because they do not modify the physicochemical properties of the broth [18]. This is not entirely true in the case of intensive foaming because the distance between the liquid surface and the foamdisk leads to the formation of a persistent layer of foam (Fig.…”

Section: Resultsmentioning

confidence: 93%

Physical and physiological impacts of different foam control strategies during a process involving hydrophobic substrate for the lipase production by Yarrowia lipolytica

Kar

Destain

Thonart

et al. 2011

Bioprocess Biosyst Eng

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The potentialities for the intensification of the process of lipase production by the yeast Yarrowia lipolytica on a renewable hydrophobic substrate (methyl oleate) have to be investigated. The key factor governing the lipase yield is the intensification of the oxygen transfer rate, considering the fact that Y. lipolytica is a strict aerobe. However, considering the nature of the substrate and the capacity for protein excretion and biosurfactant production of Y. lipolytica, intensification of oxygen transfer rate is accompanied by an excessive formation of foam. Two different foam control strategies have thus been implemented: a classical chemical foam control strategy and a mechanical foam control (MFM) based on the Stirring As Foam Disruption principle. The second strategy allows foam control without any modifications of the physico-chemical properties of the broth. However, the MFM system design induced the formation of a persistent foam layer in the bioreactor. This phenomenon has led to the segregation of microbial cells between the foam phase and the liquid phase in the case of the bioreactors operated with MFM control, and induced a reduction at the level of the lipase yield. More interestingly, flow cytometry experiments have shown that the residence time of microbial cells in the foam phase tends to induce a dimorphic transition which could potentially explain the reduction of lipase excretion.

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Effect of antifoam agents on the medium and microbial cell properties and process performance in small and large reactors

Cited by 32 publications

References 22 publications

Silicone antifoam performance enhancement by nonionic surfactants in potato medium

Silicone antifoam performance enhancement by nonionic surfactants in potato medium

Continuous rhamnolipid production with integrated product removal by foam fractionation and magnetic separation of immobilized Pseudomonas aeruginosa

Physical and physiological impacts of different foam control strategies during a process involving hydrophobic substrate for the lipase production by Yarrowia lipolytica

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