Capillary Isoelectric Focusing and Fluorometric Detection of Proteins and Microorganisms Dynamically Modified by Poly(ethylene glycol) Pyrenebutanoate

Determination of Pathogens by Electrophoretic and Spectrometric Techniques

In modern medical diagnostics, where analytical chemistry plays a key role, fast and accurate identification of pathogens is becoming increasingly important. Infectious diseases pose a growing threat to public health due to population growth, international air travel, bacterial resistance to antibiotics, and other factors. For instance, the detection of SARS-CoV-2 in patient samples is a key tool to monitor the spread of the disease. While there are several techniques for identifying pathogens by their genetic code, most of these methods are too expensive or slow to effectively analyze clinical and environmental samples that may contain hundreds or even thousands of different microbes. Standard approaches (e.g., culture media and biochemical assays) are known to be very time- and labor-intensive. The purpose of this review paper is to highlight the problems associated with the analysis and identification of pathogens that cause many serious infections. Special attention was paid to the description of mechanisms and the explanation of the phenomena and processes occurring on the surface of pathogens as biocolloids (charge distribution). This review also highlights the importance of electromigration techniques and demonstrates their potential for pathogen pre-separation and fractionation and demonstrates the use of spectrometric methods, such as MALDI-TOF MS, for their detection and identification.

Antimicrobial resins with quaternary ammonium salts as a supplement to combat the antibiotic resistome in drinking water treatment plants

The increasing finding of pathogens and antibiotic resistance genes (ARGs) in drinking water has become one of the most challenging global health threats worldwide. However, conventional disinfection strategies in drinking water treatment plants (DWTPs) require further optimization in combating the antibiotic resistome. Here, we show that antimicrobial resins with quaternary ammonium salts (AMRs-QAS) exhibit great potentials in diminishing specific potential pathogens that relatively resist chlorine or UV disinfection in DWTPs, and comprehensive analyses using microscopy and fluorescence techniques revealed that the antimicrobial capacity of AMRs-QAS mainly proceed via the bacterial adsorption and cell membrane dissociation. Moreover, a total of 15 among 30 selected ARGs, as well as 4 selected potential pathogens including Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli and Staphylococcus aureus were all detected in the source water. Coupling the AMRs-QAS with 0.2 mg/L chlorine resulted in higher removal efficiencies than chlorination (2 mg/L) or UV disinfection (400 mJ cm^-2) for all the detected pathogens and ARGs in drinking water and significantly decreased the relative abundances of Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, as well as all the detected ARGs (p < 0.05). Co-occurrences of pathogens and ARGs were revealed by a correlation network and possibly accounts for the ARGs removal. This coupled disinfection strategy overcomes the limitations of individual disinfection methods, i.e. the enrichment of specific pathogens and ARGs among bacterial populations, and provides an alternative for minimizing health risks induced by the antibiotic resistome in DWTPs.

Microbial Analysis of Escherichia coli ATCC, Lactobacteria and Saccharomyces cerevisiae Using Capillary Electrophoresis Approach

Rapid detection and identification of microorganisms is a challenging and important aspect in many areas of our life, beginning with medicine, ending with industry. Unfortunately, classical methods of microorganisms identification are based on time-consuming and labor-intensive approaches. Screening techniques require rapid and cheap grouping of bacterial isolates; however, modern bioanalytics demands comprehensive bacterial studies on molecular level. The new approach to the rapid identification of bacteria is to use the electromigration techniques, especially capillary zone electrophoresis (CZE). CZE is an important technique used in the analysis of microorganisms. However, the analysis of microbial complexes using this technology still encounters several problems-uncontrolled aggregation and/or adhesion to the capillary surface. One way to resolve this issue is the CZE analysis of microbial cell with surface charge modification by bivalent metal ions (e.g., Ca(2+) aq, Zn aq). Under the above conditions, bacterial cells create compact aggregates, and fewer high-intensity signals are observed in electropherograms. The chapter presents the capillary electrophoresis of microbial aggregates approach with UV and one-dimensional intact cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (ICM MS) detection.

Capillary isoelectric focusing of probiotic bacteria from cow's milk in tapered fused silica capillary with off-line matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identification

In this study, combination of capillary isoelectric focusing (CIEF) in tapered fused silica (FS) capillary with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is presented as an efficient approach for unambiguous identification of probiotic bacteria in real sample. For this purpose, bacteria within genus Lactobacillus were selected as model bioanalytes and cow's milk was selected as a biological sample. CIEF analysis of both the cultivated bacteria and the bacteria in the milk was optimized and isoelectric points characterizing the examined bacteria were subsequently determined independently of the bacterial sample origin. The use of tapered FS capillary significantly enhanced the separation capacity and efficiency of the CIEF analyses performed. In addition, the cell number injected into the tapered FS capillary was quantified and an excellent linearity of the calibration curves was achieved which enabled quantitative analysis of the bacteria by CIEF with UV detection. The minimum detectable number of bacterial cells was 2×10(6) mL(-1). Finally, cow's milk spiked with the selected bacterium was analyzed by CIEF in tapered FS capillary, the focused and detected bacterial cells were collected from the capillary, deposited onto the cultivation medium, and identified using MALDI-TOF MS afterward. Our results have revealed that the proposed procedure can be advantageously used for unambiguous identification of probiotic bacteria in a real sample.

Recent developments in capillary and chip electrophoresis of bioparticles: Viruses, organelles, and cells

In appropriate aqueous buffer solutions, biological particles usually exhibit a particular electric surface charge due to exposed charged or chargeable functional groups (amino acid residues, acidic carbohydrate moieties, etc.). Consequently, these bioparticles can migrate in solution under the influence of an electric field allowing separation according to their electrophoretic mobilities or their pI values. Based on these properties, electromigration methods are of eminent interest for the characterization, separation, and detection of such particles. The present review discusses the research papers published between 2008 and 2010 dealing with isoelectric focusing and zone electrophoresis of viruses, organelles and microorganisms (bacteria and yeast cells) in the capillary and the chip format.

Capillary isoelectric focusing with pH 9.7 cathode for the analysis of gastric biopsies

Capillary isoelectric focusing tends to suffer from poor reproducibility, particularly for the analysis of complex protein samples from cellular or tissue homogenates. This poor reproducibility appears to be associated with erratic variations in electroosmotic flow. One cause of electroosmotic flow variation is degradation of the capillary coating caused by the extremely basic solution commonly used during mobilization and focusing; this degradation of the capillary coating can be reduced by employing a CAPS mobilization buffer at pH 9. Another cause of variation is protein adsorption to the capillary wall, which causes an increase in electroosmotic flow. The effects of protein adsorption can be reduced by use of surfactants in the buffer and by employing an extremely low sample loading. We report the use of CAPS mobilization buffer in combination with an ultrasensitive laser-induced fluorescence detector for the reproducible analysis of ∼2 ng of protein from a Barrett's esophagus biopsy.

Capillary isoelectric focusing of individual mitochondria

Mitochondria are highly heterogeneous organelles that likely have unique isoelectric points (pI), which are related to their surface compositions and could be exploited in their purification and isolation. Previous methods to determine pI of mitochondria report an average pI. This article is the first report of the determination of the isoelectric points of individual mitochondria by capillary isoelectric focusing (cIEF). In this method, mitochondria labeled with the mitochondrial-specific probe 10-N-nonyl acridine orange (NAO) are injected into a fused-silica capillary in a solution of carrier ampholytes at physiological pH and osmolarity, where they are focused then chemically mobilized and detected by laser-induced fluorescence (LIF). Fluorescein-derived pI markers are used as internal standards to assign a pI value to each individually detected mitochondrial event, and a mitochondrial pI distribution is determined. This method provides reproducible distributions of individual mitochondrial pI, accurate determination of the pI of individual mitochondria by the use of internal standards, and resolution of 0.03 pH units between individual mitochondria. This method could also be applied to investigate or design separations of organelle subtypes (e.g., subsarcolemmal and interfibrillar skeletal muscle mitochondria) and to determine the pIs of other biological or nonbiological particles.

Separation of attogram terpenes by the capillary zone electrophoresis with fluorometric detection

An original method based on capillary zone electrophoresis with fluorimetric detection has been developed for the determination of terpenic compounds. The method is based on the separation of a terpenes dynamically labeled by the non-ionogenic tenside poly(ethylene glycol) pyrenebutanoate, which was used previously for the labeling of biopolymers. The background electrolytes were composed of taurine-Tris buffer (pH 8.4). In addition to the non-ionogenic tenside aceton and poly(ethylene glycol) were used as the additives. The capillary zone electrophoresis with fluorometric detection at the excitation wavelength 335 nm and the emission wavelength 463 nm was successfully applied to the analysis of tonalid, cholesterol, vitamin A, ergosterol, estrone and farnesol at level of 10(-17) mol L(-1). Farnesol, is produced by Candida albicans as an extracellular quorum-sensing molecule that influences expression of a number of virulence factors, especially morphogenesis and biofilm formation. It enables this yeast to cause serious nosocomial infections. The sensitivity of this method was demonstrated on the separation of farnesol directly from the cultivation medium.

Recent advances in the analysis of biological particles by capillary electrophoresis

This review covers research papers published in the years 2005-2007 that describe the application of capillary electrophoresis to the analysis of biological particles such as whole cells, subcellular organelles, viruses and microorganisms.

Separation of plant pathogens from different hosts and tissues by capillary electromigration techniques

In this contribution capillary isoelectric focusing and capillary zone electrophoresis were applied for the separation and detection of different plant pathogens including Pseudomonas syringae pv. syringae, P. syringae pv. lachrymans, Pseudomonas savastanoi pv. fraxinus, P. savastanoi pv. olea, Agrobacterium tumefaciens, A vitis, Xanthomonas arboricola pv. juglandis, X. campestris pv. zinniae, and Curtobacterium sp.. The UV detection and sensitive fluorescence detection of the native phytopathogens or those dynamically modified by the nonionogenic fluorescent tenside based on pyrenebutanoate were used. The isoelectric points of the labeled phytopathogens were found comparable with the pI of the native compounds. No influence of the hosts on pIs of the strains of the genus Pseudomonas was observed. The identification of plant pathogens by gas chromatographic analysis of fatty acid methyl esters was compared with results of capillary isoelectric focusing. Capillary electromigration was successfully applied for the separation of microbes directly from plant tissue suspensions.

CE separation of proteins and yeasts dynamically modified by PEG pyrenebutanoate with fluorescence detection

The optimized protocols of the bioanalytes separation, proteins and yeasts, dynamically modified by the nonionogenic tenside PEG pyrenebutanoate, were applied in CZE and CIEF with the acidic gradient in pH range 2-5.5, both with fluorescence detection. PEG pyrenebutanoate was used as a buffer additive for a dynamic modification of proteins and/or yeast samples. The narrow peaks of modified analytes were detected. The values of the pI's of the labeled proteins were calculated using new fluorescent pI markers in CIEF and they were found to be comparable with pI's of the native compounds. As an example of the possible use of the suggested CIEF technique, the mixed cultures of yeasts, Candida albicans, Candida glabrata, Candida kefyr, Candida krusei, Candida lusitaniae, Candida parapsilosis, Candida tropicalis, Candida zeylanoides, Geotrichum candidum, Saccharomyces cerevisiae, Trichosporon asahii and Yarrowia lipolytica, were reproducibly focused and separated with high sensitivity. Using UV excitation for the on-column fluorometric detection, the minimum detectable amounts of analytes, femtograms of proteins and down to ten cells injected on the separation capillary, were estimated.

Capillary isoelectric focusing of native and inactivated microorganisms

The research of microorganisms includes the development of methods for the inactivation of viruses and other microbes. It also means to efficiently eliminate the infectivity of microorganisms without damage of their integrity and structure. According to the results of the last 5 years the capillary electromigration techniques appear to be very perspective for the comparison of the methods applicable for inactivation in the diagnostics and study of the pathogens. In this paper we suggest the capillary isoelectric focusing of the model microorganisms, Escherichia coli, Staphylococcus epidermidis, Candida albicans and bacteriophage PhiX 174, native or inactivated by different procedures. UV detection and fluorometric detection for the dynamically modified microbes by pyrenebutanoate on the basis of the non-ionogenic tenside were used here. Isoelectric points of native and/or dynamically modified microorganisms and other properties were compared with those obtained after microorganisms inactivation. The segmental injection of the sample pulse enabled the reproducible and efficient capillary isoelectric focusing in different pH gradients. The low-molecular-weight pI markers were used for tracing of the pH gradient.