Distribution of Cells between Solid/Liquid and Liquid/Liquid Interfaces

Abstract

The use of aqueous two-phase systems (ATPSs) and each system's individual phase-forming species to prevent Streptococcus sanguis attachment onto hydroxyapatite discs was explored. The strategy that we followed was to attach the cells to a solid surface in the presence of an additional interface. Conditions under which, simultaneously, the phase-forming species form two phases and the cells proliferate were identified. Growth curves were constructed in the presence of various polymers and salts commonly used to prepare ATPSs. Several aqueous two-phase systems were selected such that bacterial growth was comparable to that observed in pure medium. Cells were allowed to attach to hydroxyapatite discs for 7 days in the presence of varying concentrations of media, media with polymer, media with salt, and media with ATPS. Streptococcus sanguis attachment to the disks was evaluated by scanning electron microscopy. The addition of a PEG/Na(2)SO(4) ATPS to high concentrations of yeast-tryptone (YT) media (>65%) and of a PEG/MgSO(4) ATPS to nutrient-limited media reduces surface coverage of S. sanguis to less than 10%. Comparison of the attachment levels for the systems containing PEG/Na(2)SO(4) to media containing the individual phase-forming species and to the YT reference systems indicated that nutrient availability did not affect attachment.

Unique Phase Behaviors in the Gemini Surfactant/EAN Binary System: The Role of the Hydroxyl Group

“…ASTPs have therefore received much attention for the applications in separation and purification. 54,55 In our system, the two coexisting phases started at C 12-3OH-12 a little larger than CMC and ended at about C 12-3OH-12 of 55%. Considering the relatively larger density of EAN (1.2 g•cm −3 ) than 12-3OH-12 (1.1 g•cm −3 ), the UP was supposed to be a surfactant rich phase and the LP was a solvent rich phase.…”

Improving reliability of live/dead cell counting through automated image mosaicing

“…However, they all work in the same way: the counting chamber is delineated by a grid (impressed or painted) containing a fixed sample volume. The operator counts the cells inside the grid where the dead ones are typically highlighted using Trypan Blue [54]. The number of live and dead cells present in the whole culture is finally obtained by multiplying the number of counted cells by the dilution factor used.…”

The Interphase Electric Properties of SDS/n‐C5H11OH/L‐Phenylalanine/H2O System

“…Determination of the Distribution of L-phe in the Upper and Lower Phases in SDS/n-C 5 H 11 OH/L-phe/H 2 …”