The differentiation and identification of pathogenic bacteria using FT-IR and multivariate statistical analysis

Correspondence analysis was used to classify the pattern-like FT-IR spectra of intact bacteria. The analysis was performed on a data set of approximately 80 normalized spectral derivatives of a selection of pathogenic bacteria. The correspondence analysis proved that the various different bacterial species were clustering in distinct regions of the correspondence maps suggesting that there do exist correlations between spectral data and biochemical/microbiological classification.     

Rapid characterization of Bacillus spores targeting species-unique peptides produced with an atmospheric pressure matrix-assisted laser desorption/ionization source

New and improved strategies are eagerly sought for the rapid identification of microorganisms, particularly in mixtures. Mass spectrometry remains a powerful tool for this purpose. Small acid-soluble proteins (SASPs), which are relatively abundant in Bacillus spores, represent potential biomarkers for species characterization. Despite sharing extensive sequence homology, these proteins differ sufficiently in sequence for discrimination between species. This work focuses on the differences in sequence between SASPs from various Bacillus species. Compilation of SASP sequences from protein database searches, followed by in silico trypsin digestion and analysis of the resulting fragments, identified several species-specific peptides that could be targeted for analysis using mass spectrometry. This strategy was tested and found to be successful in the characterization of Bacillus spores both from individual species and in mixtures. Analysis was performed using an ion trap mass spectrometer with an atmospheric pressure MALDI source. This instrumentation offers the advantage of increased speed of analysis and accurate precursor ion selection for tandem mass spectrometric analysis compared with vacuum matrix-assisted laser desorption/ionization and time-of-flight instruments. The identification and targeting of species-specific peptides using this type of instrumentation offers a rapid, efficient strategy for the identification of Bacillus spores and can potentially be applied to different microorganisms.     

Multiplex identification of bacteria in bacterial mixtures with surface‐enhanced Raman scattering

Surface‐enhanced Raman scattering (SERS) is a technique capable of identifying each component in a mixture because of its intrinsically narrow spectral bands. In a clinical setting, the identification of bacteria from its initial culture by collecting the colonies on the culture plate significantly decreases the analysis time and the cost. The identification of bacteria from their mixtures is attempted using SERS. A simple mixing procedure of bacterial samples and concentrated colloidal suspension is proven to be mostly satisfactory for the generation of the reproducible SERS spectra that can be used for bacterial identification. The mixture of three different but related bacterial species Shigella sonnei, Proteus vulgaris, and Erwinia amylovara and three Escherichia coli strains (BFK13, BHK7, DH5 α) are used as model systems to test the feasibility of the approach. The results indicate that it is possible to identify the composition of a bacterial mixture. This approach can easily be utilized for the bacteria originating from the same source with similar growth profiles. Copyright © 2009 John Wiley & Sons, Ltd.     

A novel method for urinary tract infection diagnosis and antibiogram using Raman spectroscopy

Urinary tract infection (UTI) diagnosis and antibiogram require a 48‐h waiting period using the standard conventional clinical methods. This long waiting period results in ineffective treatments, increased costs and, most importantly, in increased resistance to antibiotics. In this work, a novel method for classifying bacteria and determining their sensitivity to an antibiotic using Raman spectroscopy is described. Raman spectra belonging to three species of gram‐negative enterobacteria, which are most commonly responsible for UTIs, are classified with over 94% accuracy using novel feature extraction and discriminant analysis. Sensitivity to ciprofloxacin is also clearly evident as early as 2 h after treatment by differences in the Raman spectra of bacteria treated or not treated with this antibiotic. The proposed technique can become the basis for the development of new technology for UTI diagnosis and antibiogram with same day results, thus avoiding urine cultures and all undesirable consequences of current practice. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of Inoculated Lactic Acid Fermentation on the Fermentable Saccharides and Polyols,Polyphenols and Antioxidant Activity Changes in Wheat Sourdough

Inoculation of sourdough allows the fermentation medium to be dominated by desired microorganisms, which enables determining the kinetics of the conversion of chemical compounds by individual microorganisms. This knowledge may allow the design of functional food products with health features dedicated to consumers with special needs. The aim of the study was to assess the dynamics of transformations of fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) compounds from wheat flour as well as their antioxidant activity during inoculated and spontaneous sourdough fermentation. The FODMAP content in grain products was determined by the fructan content with negligible amounts of sugars and polyols. To produce a low-FODMAP cereal product, the fermentation time is essential. The 72 h fermentation time of L. plantarum-inoculated sourdough reduced the FODMAP content by 91%. The sourdough fermentation time of at least 72 h also positively influenced the content of polyphenols and antioxidant activity, regardless of the type of fermentation. The inoculation of both L. plantarum and L. casei contributed to a similar degree to the reduction in FODMAP in sourdough compared to spontaneous fermentation.     

DMOA-based meroterpenoids with diverse scaffolds from the sponge-associated fungus Penicillium brasilianum

Bioinformatics analysis of the synthetic gene clusters in association with the qRT-PCR detection led to speculate a marine derived fungus, Penicillium brasilianum WZXY-m122-9, to be potential to produce meroterpenoids. Chromatographic separation of the EtOAc extract of this fungal strain on a large-scale fermentation resulted in the isolation of six new DMOA-related meroterpenoids, namely brasilianoids G?L (1–6), together with nine known meroterpenes. Their structures were determined by extensive analyses of spectroscopic data, including the X-ray diffraction and the ECD data for configurational assignment. Brasilianoid G is characterized by the presence of an unprecedented scaffold bearing a 6/6/5/5/5 pentacyclic nucleus, while brasilianoid K possessing a 7/6/6/6/5 pentacyclic system is uncommonly found from nature. The biogenetic relationship among the isolated compounds was postulated based on the comparative analyses of gene clusters. Brasilianoid L (6), austinol (12), and dehydroaustin (14) exhibited significant inhibition against bacteria invasion into host cells, that was suggested to be mediated by preventing the polymerization of actin in the host cells.     

Novel rearranged acetophenone derivatives possessing diverse architectures from the leaves of Melicope ptelefolia

Melicolones C–K (1–9), nine acetophenone derivatives with three unprecedented architectures, were characterized from the leaves of Melicope ptelefolia. Among them, melicolone C (1) was a novel acetophenone analogue possessing a highly rearranged spiro skeleton. Melicolones D-F (2–4) were three novel acetophenone congeners bearing unusual octalactone ring. Melicolones G-K (5–9) were five new prenylated acetophenone derivatives featuring a 9-oxatricyclo [3.2.1.13, 8]nonane core. Their structures were established by extensive spectroscopic analysis and ECD spectra. These different structures were presumably derived from the same precursor via three major biosynthetic pathways. Compounds 5–9 exerted moderate effects to reverse multidrug-resistance in MCF-7/ADR cells with reversal fold values ranging from 6.2 to 13.3.     

Sulfonium,an Underestimated Moiety for Structural Modification,Alters the Antibacterial Profile of Vancomycin Against Multidrug‐Resistant Bacteria

In the antibiotics arsenal, vancomycin is a last resort for the treatment of intractable infections. However, this situation is under threat because of the increasing appearance of vancomycin‐resistant bacteria (VRB). Herein, we report a series of novel vancomycin derivatives carrying a sulfonium moiety. The sulfonium–vancomycin derivatives exhibited enhanced antibacterial activity against VRB both in vitro and in vivo. These derivatives also exhibited activity against some Gram‐negative bacteria. The sulfonium modification enhanced the interaction of vancomycin with the bacterial cell membrane and disrupts membrane integrity. Furthermore, the in vivo pharmacokinetic profile, stability, and toxicity of these derivatives demonstrated good druggability of the sulfonium–vancomycin analogues. This work provides a promising strategy for combating drug‐resistant bacterial infection, and advances the knowledge on sulfonium derivatives for structural optimization and drug development.     

Synthesis,characterization and antimicrobial study via new heterocyclic derivatives of trimethoprim

New compounds of trimethoprim heterocyclic derivatives were synthesized. These compounds were synthesized through the condensation reaction between trimethoprim with bromoacetic acid to yield compound 1. Several Schiff bases 2–7 have been synthesized by the condensation different aromatic aldehydes with compound 1. Compound 8 were formed from the reaction of sodium nitrite and acetyl acetone in presence of conc. hydrogen chloride to obtain the hydrazono derivative; then, Cyclocondensation of compound 8 with hydrazine hydrate, phenyl hydrazine and dinitrophenyl hydrazine respectively to yield compounds 9–11 in ethanol affording the pyrazoline derivatives. This work involves the synthesis of some 1,2,3-Triazoles derived from compound 1 by the action of sodium azide on the diazonium chloride salt to yield 5-azido-8-(3,4,5-trimethoxybenzyl)imidazo[1,2-c]pyrimidin-3(2H)-one 12. Finally, by reaction of 12 with acetyl acetone and ethyacetoacetate; respectively in sodium ethoxide/ethanol as a solvent to form compounds 13, 14. The structures of the compounds 1–14 were characterized by elemental analysis, spectral data and antimicrobial evaluation of the some newly synthesized compounds and found that the synthesized compounds are active against tested Gram positive and Gram negative bacteria like Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Proteus.     

Electron holography of biological samples

In this paper, we summarise the development of off-axis electron holography on biological samples starting in 1986 with the first results on ferritin from the group of Tonomura. In the middle of the 1990s strong interest was evoked, but then stagnation took place because the results obtained at that stage did not reach the contrast and the resolution achieved by conventional electron microscopy.

To date, there exist only a few (12) publications on electron holography of biological objects, thus this topic is quite small and concise. The reason for this could be that holography is mostly established in materials science by physicists. Therefore, applications for off-axis holography were powerfully pushed forward in the area of imaging, e.g. electric or magnetic micro- and nanofields. Unstained biological systems investigated by means of off-axis electron holography up to now are ferritin, tobacco mosaic virus, a bacterial flagellum, T5 bacteriophage virus, hexagonal packed intermediate layer of bacteria and the Semliki Forest virus. New results of the authors on collagen fibres and surface layer of bacteria, the so-called S-layer 2D crystal lattice are presented in this review. For the sake of completeness, we will shortly discuss in-line holography of biological samples and off-axis holography of materials related to biological systems, such as biomaterial composites or magnetotactic bacteria.