Bacteria transfer by deformation through microfiltration membrane

Abstract

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.

Removal of Bacterial Contamination from Bioethanol Fermentation System Using Membrane Bioreactor

“…This indicates that bacteria could not be readily washed out across the membrane pores and their deposition on membrane surface and pores caused pore clogging and/or membrane fouling, as evidenced by the increased TMP. While it has been reported that the flexibility of the peptidoglycan cell wall of Gram-negative bacteria (e.g., E. cloacae) may allow deformation and penetration across the membrane to some extent [28,29], the results of our tests proved otherwise. In contrast, with the membrane of 2.4 µm pore size, a noticeable decreasing and increasing trend in the concentration of bacteria in the reactor medium and permeate was observed, respectively.…”

Removal of antibiotic resistance genes in an anaerobic membrane bioreactor treating primary clarifier effluent at 20 °C

“…[80][81][82] The bacterial cell wall can be elastic and deform under pressure or become less rigid dependent on the environment, such as the presence of antibiotics. [83][84][85] The presence of foulant is known to improve the removal of extracellular DNA containing ARGs and ARB, 49 which most likely led to the variability of the microbial community and differential removal of ARGs found in the final filtrate. Optimization of the control of the level of foulant could improve ARB and ARG removal.…”

Colloid Transport in Porous Media: A Review of Classical Mechanisms and Emerging Topics

“…In porous media, the flow and shear rate distribution will yield a complex combination of the behaviours discussed above. Bacteria are capable of moving through pores sizes smaller than their body size [295]. Magnetotactic bacteria are able to travel effectively through heterogeneous porous media and overcome relatively high pore water velocities (~250µm/s) via magnetotaxis [296].…”