Investigation of microbial cell deformability by filter cake compressibility using ultrafiltration membranes

• Published in: Colloids and surfaces, B, Biointerfaces B, Biointerfaces, 2020-01, Vol.185, p.110626-110626, Article 110626
• Main Authors: Helling, Alexander, Fischer, Vivien, Eisfeld, Kristina, Schmid, Katharina, Polakovic, Milan, Thom, Volkmar
• Format: Article
• Language: English
• Subjects: Acholeplasma laidlawii; Bacteria; Bacteriophages; Brevundimonas diminuta; Cake filtration; compressibility; culture media; Deformation; filter cake; Filtration temperature; Gram-negative bacteria; Mycoplasma; peptidoglycans; polystyrenes; Pseudomonas aeruginosa; Staphylococcus epidermidis; temperature; Transmembrane pressure; ultrafiltration
• ISSN: 0927-7765; 1873-4367
• DOI: 10.1016/j.colsurfb.2019.110626

[Display omitted] •Study covers microbial cells incl. mycoplasma, common bacteria and bacteriophages.•Unified cake filtration method enabling a direct comparison of cake compressibility.•Simple SEM method to obtain the cake thickness at the initial status of the filter cake.•Mycoplasma are very susceptible to TMP and temperature changes in filtration.•Correlation of the obtained data to AFM and sterile filtration data from literature. This study presents the investigation of deformability of various microbial cells in terms of filter cake compressibility during cake filtration using ultrafiltration membranes in dead-end mode. The examined microbial cells include mycoplasma, Gram-positive and Gram-negative bacteria, and Pseudomonas aeruginosa phage PP7. Polystyrene particles were used as an incompressible reference. The compressibility results were correlated to the deformability of a microbial cell, induced by its cell envelope. To determine the deformability of the different microbial cells under different process conditions, their cake resistance was measured under varying pressures from 10 to 250 kPa and temperatures from 2 to 35 °C. In addition, the influence of different culture media on the cell properties of Acholeplasma laidlawii and its behavior under different pressure and temperature was determined. The results of the pressure and temperature experiments revealed that Gram-positive S. epidermidis was found to be relatively stiff due to the thickness of the peptidoglycan layer, under different pressure and temperature conditions. No significant increase of the specific cake resistance of S. epidermidis could be determined. B. diminuta however showed a high deformation tendency when the pressure was increased indicating relatively soft cells. Mycoplasma A. laidlawii cells cultivated in three different media showed a different, but significant, effect of pressure and temperature.