Selective isolation of bacteria for metagenomic analysis: Impact of membrane characteristics on bacterial filterability

Nnadozie, Chika Felicitas; Lin, Johnson; Govinden, Roshini

doi:10.1002/btpr.2109

Cited by 18 publications

(13 citation statements)

References 133 publications

(275 reference statements)

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“…Confirming previous reports in the literature, the depth filter (glass microfiber membrane) is efficient in removing potential foulants, but retains significant numbers of microorganisms for reasons described by Nnadozie et al A 3‐h enrichment step was, therefore, added to precede the 10 min enzyme treatment and subsequent prefiltration. This approach increased the number of cells by a factor of 2 (from 35% to 70%).…”

Section: Resultssupporting

confidence: 76%

“…Protocols based on commercially available modules represent a critical step in enabling other laboratories to use an approach that combines enzyme treatment, cross‐flow HF microfiltration, and short enrichment times to recover high concentrations of viable bacteria. As reviewed by Nnadozie et al, complex interactions between sample and membrane surfaces require that the protocols for recovery of microorganisms from environmental samples be developed on a case‐by‐case basis.…”

Section: Introductionmentioning

confidence: 99%

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Accelerating sample preparation through enzyme‐assisted microfiltration of Salmonella in chicken extract

Vibbert

Luo

et al. 2015

Biotechnology Progress

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Microfiltration of chicken extracts has the potential to significantly decrease the time required to detect Salmonella, as long as the extract can be efficiently filtered and the pathogenic microorganisms kept in a viable state during this process. We present conditions that enable microfiltration by adding endopeptidase from Bacillus amyloliquefaciens to chicken extracts or chicken rinse, prior to microfiltration with fluid flow on both retentate and permeate sides of 0.2 μm cutoff polysulfone and polyethersulfone hollow fiber membranes. After treatment with this protease, the distribution of micron, submicron, and nanometer particles in chicken extracts changes so that the size of the remaining particles corresponds to 0.4-1 μm. Together with alteration of dissolved proteins, this change helps to explain how membrane fouling might be minimized because the potential foulants are significantly smaller or larger than the membrane pore size. At the same time, we found that the presence of protein protects Salmonella from protease action, thus maintaining cell viability. Concentration and recovery of 1-10 CFU Salmonella/mL from 400 mL chicken rinse is possible in less than 4 h, with the microfiltration step requiring less than 25 min at fluxes of 0.028-0.32 mL/cm(2) min. The entire procedure-from sample processing to detection by polymerase chain reaction-is completed in 8 h.

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Section: Resultssupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Accelerating sample preparation through enzyme‐assisted microfiltration of Salmonella in chicken extract

Vibbert

Luo

et al. 2015

Biotechnology Progress

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“…Multiple reports showed that foods could be filtered through membranes in quantities useful for conventional detection procedures (such as plating), although cross‐flow microfiltration or ultrafiltration of cells and proteins resulted in fouling of the membrane and limited the volume of sample that could be processed . We showed that endopeptidase treatment followed by hollow fiber microfiltration was effective in overcoming fouling of the hollow fiber membrane, while avoiding loss of viability of the Salmonella cells .…”

Section: Resultsmentioning

confidence: 84%

Protein particulate retention and microorganism recovery for rapid detection of Salmonella

Kreke

Ximenes

et al. 2017

Biotechnology Progress

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The rapid detection of Salmonella in ground meat requires that living microorganisms be brought to levels detectable by PCR, immunoassays, or similar techniques within 8 h. Previously, we employed microfiltration using hollow fiber membranes to rapidly process and concentrate viable bacteria in food extracts through a combination of enzyme treatment and prefiltration in order to prevent blockage or fouling of the hollow fiber membranes. However, scanning electron microscopy and particle size analysis of enzyme hydrolysates showed that enzyme treatment followed by filtration caused submicron particles to form and be trapped within the prefiltration media, which in turn, retained about 80% of the bacteria. Filtering prior to enzyme treatment resulted in formation of a filter cake consisting of protein particles retained on the surface of the filter, while facilitating passage of the much smaller microorganisms through the filter, separating them from particulates. Subsequent enzyme treatment of the filtrate resulted in an extract that was microfiltered in less than an hour, while concentrating viable microorganisms in the extract by 500×. An inoculum of Salmonella enterica cells into turkey burger containing of 1-20 CFU/mL, consisting of spiked cells plus cells already present in the turkey burger sample, was rapidly brought to levels detectable by conventional PCR and BAX PCR assays. The entire procedure from sample processing to detection of Salmonella enterica was achieved in less than 8 h. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:687-695, 2017.

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“…Living unicellular particles such as bacteria, yeasts, algae or red blood cells exhibit, in environmental conditions, a large variability of individual particle size, shape and envelope flexibility. Effectively, in the specific case of bacteria filtration, the cell size of the microorganisms is not the only parameter which determines the transfer through the membrane [10]. Recent works demonstrated that the shape of the bacteria cell [3] and the Gram type [7,8], which characterize the cell wall composition, are also important parameters that play a key role in the particle retention.…”

Section: Introductionmentioning

confidence: 99%

Bacteria transfer by deformation through microfiltration membrane

Gaveau

Coetsier

Roques

et al. 2017

Journal of Membrane Science

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Living particles such as bacteria are able to transfer through membrane pores that are smaller than cell size due to the specific stiffness of this type of microorganism. This phenomenon can lead to a significant loss of selectivity in the filtration process, which is a major cause of concern in the sterilizing filtration step. This study investigates the retention of three bacteria strains: Escherichia coli CIP 54124, Pseudomonas aeruginosa CIP 103467 and Staphylococcus aureus CIP 53154 by model porous membranes for various operating conditions (transmembrane pressure, feed concentration and the physicochemical composition of filtered media with antibacterial agent added at sublethal concentration). The first part of this study is dedicated to defining the size and the nanomechanical properties of the envelope of the studied bacteria by microscopic techniques (Transmission electron microscopy & Atomic-force microscopy), in order to then explore the role of these quantifiable characteristics on the cell transfer through the pores by deformation mechanisms. Our results lead to the development of a numerical model to connect the observed retention efficiency of the filtration experiment and the microscopic information about individual particles.

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Selective isolation of bacteria for metagenomic analysis: Impact of membrane characteristics on bacterial filterability

Cited by 18 publications

References 133 publications

Accelerating sample preparation through enzyme‐assisted microfiltration of Salmonella in chicken extract

Accelerating sample preparation through enzyme‐assisted microfiltration of Salmonella in chicken extract

Protein particulate retention and microorganism recovery for rapid detection of Salmonella

Bacteria transfer by deformation through microfiltration membrane

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