Application of periodic backpulsing to reduce membrane fouling during ultrafiltration of plasmid DNA

Borujeni, Ehsan Espah; Liu, Ying; Zydney, Andrew L.

doi:10.1016/j.memsci.2014.08.059

Cited by 13 publications

(11 citation statements)

References 20 publications

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“…Because many of micro‐ or ultra‐filtration processes in the literature target separations involving biofunctional molecules from proteinaceous environments, maintaining the original characteristics of the target protein in these cases is crucial. Therefore, relatively mild conditions consisting of dipolar or hydrolphilic membranes, detergents, or back pressure have been used to mitigate membrane fouling while preserving the characteristics of the target proteins . Our work employed a unique approach for preventing fouling in a special situation, i.e., concentrating living microorganisms in the presence of enzyme hydrolyzed egg whites where the target is the microorganism rather than a protein.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, relatively mild conditions consisting of dipolar or hydrolphilic membranes, detergents, or back pressure have been used to mitigate membrane fouling while preserving the characteristics of the target proteins. [17][18][19][20] Our work employed a unique approach for preventing fouling in a special situation, i.e., concentrating living microorganisms in the presence of enzyme hydrolyzed egg whites where the target is the microorganism rather than a protein.…”

Section: Introductionmentioning

confidence: 99%

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Microfiltration of enzyme treated egg whites for accelerated detection of viable Salmonella

Ximenes

Kreke

et al. 2016

Biotechnology Progress

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We report detection of <13 CFU of Salmonella per 25 g egg white within 7 h by concentrating the bacteria using microfiltration through 0.2-μm cutoff polyethersulfone hollow fiber membranes. A combination of enzyme treatment, controlled cross-flow on both sides of the hollow fibers, and media selection were key to controlling membrane fouling so that rapid concentration and the subsequent detection of low numbers of microbial cells were achieved. We leveraged the protective effect of egg white proteins and peptone so that the proteolytic enzymes did not attack the living cells while hydrolyzing the egg white proteins responsible for fouling. The molecular weight of egg white proteins was reduced from about 70 kDa to 15 kDa during hydrolysis. This enabled a 50-fold concentration of the cells when a volume of 525 mL of peptone and egg white, containing 13 CFU of Salmonella, was decreased to a 10 mL volume in 50 min. A 10-min microcentrifugation step further concentrated the viable Salmonella cells by 10×. The final cell recovery exceeded 100%, indicating that microbial growth occurred during the 3-h processing time. The experiments leading to rapid concentration, recovery, and detection provided further insights on the nature of membrane fouling enabling fouling effects to be mitigated. Unlike most membrane processes where protein recovery is the goal, recovery of viable microorganisms for pathogen detection is the key measure of success, with modification of cell-free proteins being both acceptable and required to achieve rapid microfiltration of viable microorganisms. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1464-1471, 2016.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microfiltration of enzyme treated egg whites for accelerated detection of viable Salmonella

Ximenes

Kreke

et al. 2016

Biotechnology Progress

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“…Transmembrane pressure (TMP) and permeate flux are key indicators of microfiltration membrane fouling. In the presence of colloidal material and fouling components, the TMP increases across the filter module and flux gradually decreases . This is avoided by including a prefiltration step using a nylon filter.…”

Section: Resultsmentioning

confidence: 99%

Microbial enrichment and multiplexed microfiltration for accelerated detection of Salmonella in spinach

Ximenes

Kreke

et al. 2019

Biotechnology Progress

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To attain Salmonella detection thresholds in spinach suspensions using enrichment media requires at least 24 hr. Separation and concentration of selected microorganisms via microfiltration and microfugation reduce time for sample preparation, especially when working with large volumes of vegetable suspensions. This facilitates accelerated detection of Salmonella in spinach suspensions, and may contribute to effectively monitoring this pathogen before it reaches the consumer. We report a microfiltration‐based protocol for accelerated sample preparation to concentrate and recover ≤1 colony forming unit (CFU) Salmonella/g pathogen‐free spinach. Store‐bought samples of spinach and a spinach plant subjected to two environmental conditions (temperature and light exposure) during its production were tested. The overall procedure involves extraction with buffer, a short enrichment step, prefiltration using a nylon filter, crossflow hollow fiber microfiltration, and retentate centrifugation to bring microbial cells to detection levels. Based on 1 CFU Salmonella/g frozen spinach, and a Poisson distribution statistical analyses with 99% probability, we calculated that 3 hr of incubation, when followed by microfiltration, is sufficient to reach the 2 log concentration required for Salmonella detection within 7 hr. Longer enrichment times (5 hr or more) is needed for concentrations lower than 1 CFU Salmonella/g of ready to eat spinach. The recovered microbial cells were identified and confirmed as Salmonella using both polymerase chain reaction (PCR) and plating methods. Different environmental conditions tested during production did not affect Salmonella viability; this demonstrated the broad adaptability of Salmonella and emphasized the need for methods that enable efficient monitoring of production for the presence of this pathogen.

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“…In this section, we will try to relate the findings of the mathematical model presented in this paper to the following papers reporting the use of back-shocking in ultrafiltration [11,10,7,6,3,9,12,48].…”

Section: Relating the Results To The Literaturementioning

confidence: 99%

“…This is in reasonable agreement with the results presented in this model. In [48] ultrafiltration of plasmid DNA is performed under laminar conditions using a hollow fibre membrane with inner diameter of the hollow fibres of 0.5 mm and a length of 30 cm. The aim of this study was to collect the supercoiled plasmid in the permeate with membranes appropriate for removing cell debris and genomic DNA, the open-circular isoform, and any plasmid dimers or higher order oligamers.…”

Section: Relating the Results To The Literaturementioning

confidence: 99%

Predicting optimal back-shock times in ultrafiltration hollow fiber modules II: Effect of inlet flow and concentration dependent viscosity

Vinther¹,

Pinelo

Brøns

et al. 2015

Journal of Membrane Science

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Application of periodic backpulsing to reduce membrane fouling during ultrafiltration of plasmid DNA

Cited by 13 publications

References 20 publications

Microfiltration of enzyme treated egg whites for accelerated detection of viable Salmonella

Microfiltration of enzyme treated egg whites for accelerated detection of viable Salmonella

Microbial enrichment and multiplexed microfiltration for accelerated detection of Salmonella in spinach

Predicting optimal back-shock times in ultrafiltration hollow fiber modules II: Effect of inlet flow and concentration dependent viscosity

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