Countercurrent Chromatographic Separation of Bacteria with Known Differences in Surface Lipopolysaccharide

Aqueous two-phase systems for biomolecule separation

Over the past thirty years, aqueous polymer two-phase technology has evolved, both experimentally and theoretically, into a separation science with many useful applications in biomolecule purification and bioconversion. This paper summarizes the developments in the applications of aqueous two-phase systems to biotechnology. The main topics to be considered are the phase diagram and its characteristics, fundamentals of biomolecule partition, large-scale and multi-stage aqueous two-phase biomolecule purification, and extractive bioconversions. The first topic involves a discussion of the thermodynamics of aqueous polymer two-phase formation and how it is influenced by such factors as polymer molecular weight and concentration, temperature, and salt type and concentration. Next, the theoretical and experimental aspects of biomolecule partition in aqueous two-phase systems will be discussed in light of the factors which influence biomolecule partition: polymer concentration and molecular weight; temperature; salt type and concentration; the addition of charged, hydrophobic and affinity derivatives. Having reviewed the fundamentals of phase diagram formation and biomolecule partition, the next two topics are applications of aqueous two-phase technology. The first set of applications involve the large-scale extraction of proteins using one to three equilibrium stages and multi-stage purifications using countercurrent distribution, liquid-liquid partition chromatography and continuous countercurrent chromatography. The second application, and very promising area for future aqueous two-phase technology, is the extractive bioconversion which permits the simultaneous production and purification of a biomolecule.

Protein separation by nonsynchronous coil planet centrifuge with aqueous-aqueous polymer phase systems

Counter-current chromatographic separation of proteins was performed using a rotary-seal-free nonsynchronous coil planet centrifuge (CPC) fabricated in our laboratory. This apparatus has a unique feature that allows a freely adjustable rotational rate of the coiled separation column at a given revolution speed. The separation was performed using a set of stable proteins including cytochrome c, myoglobin and lysozyme with two different types of aqueous-aqueous polymer phase systems, i.e., PEG (polyethylene glycol) 1000-dibasic potassium phosphate, and PEG 8000-dextran T500 in 5 mM potassium phosphate buffer. Using a set of multilayer coiled columns prepared from 0.8 mm I.D. PTFE tubing with different volumes (11, 24, 39 ml), the effect of the column capacity on the partition efficiency was investigated under a given set of experimental conditions. Among these experiments, the best separation of proteins was attained using the 39 ml capacity column with a 12.5% (w/w) PEG 1000-12.5% (w/w) dibasic potassium phosphate system at 10 rpm of coil rotation under 800 rpm. With lower phase mobile at 0.2 ml/min in the head-to-tail elution, the resolution between cytochrome c and myoglobin was 1.6 and that between myoglobin and lysozyme, 1.9. With upper phase mobile in the head-to-tail elution, the resolution between lysozyme and myoglobin peaks was 1.5. In these two separations, the stationary phase retention was 35.0 and 33.3%, respectively. Further studies were carried out using a pair of eccentric coil assemblies with 0.8 mm I.D. PTFE tubing at a total capacity of 20 ml. A comparable resolution was obtained using both lower and upper phases as a mobile phase in a head-to-tail elution. The results of our studies demonstrate that the nonsynchronous CPC is useful for protein separation with aqueous-aqueous polymer phase systems.

Recent advances in counter-current chromatography

During the past several years, counter-current chromatography (CCC) technology has been advanced to cover a broad spectrum of applications, from large-scale preparative to analytical-scale separations. These advances include liquid-liquid dual CCC, foam CCC and partition of macromolecules with aqueous-aqueous polymer phase systems. For these developments the synchronous coil planet centrifuge scheme has been used, which relies on a relatively simple mechanical design. Future developments in CCC may be focused on the improvement of the more intricate non-synchronous coil planet centrifuge scheme which has a greater potential for the separation of biopolymers and cell particles.

Counter-current chromatography. Applications to the separation of biopolymers, organelles and cells using either aqueous-organic or aqueous-aqueous phase systems

Counter-current chromatography is a form of liquid-liquid chromatography which uses low-speed centrifugation to hold one phase of an immiscible liquid pair stationary while the other is eluted through it. Two types of countercurrent chromatography are described: one suitable for preparative/analytical separation with aqueous-organic phase systems and the other for analytic fractionations using aqueous-aqueous phase systems. Applications of both processes are described, ranging from the purification of antibiotics, pesticides, and peptides to the fractionation of whole cells.

Pattern recognition analysis of in vivo enzyme-substrate fluorescence velocities in microorganism detection and identification

A spectrometric technique is presented that combines most of the important criteria necessary for efficient detection and identification of microorganisms. These criteria include simplicity of experimental design, various degrees of sensitivity and selectivity, convenience, and total reaction times of less than 15 min. The study takes advantage of the inherent extracellular enzymes present in living as opposed to dead, non-enzyme-producing organisms. Sequentially these are harnessed in in vivo reactions with a substrate containing a select organic functional group that is known to be cleaved or hydrolyzed by a certain enzyme. The substrate is tailored so that one of the products can be induced to fluoresce, and by using a conventional spectrofluorimeter the rate at which the fluorescence appears can be recorded. By subjecting the same bacterial sample to a number of different enzyme substrates, a pattern of fluorescence response rates emerges from a 7 by 7 microorganism-substrate matrix. Detection limits ranged from 3.6 X 10(2) to 3.5 X 10(8) cells per ml for the Bacillus globigii-indoxyl acetate and Escherichia coli-diacetylfluorescein pairs, respectively. The specificity and versatility of the method for bacterial determination is demonstrated in probing different bacterial enzymes through their spectrally active metabolic products.