1,720,995 research outputs found
Direct spectroscopic (FTIR) detection of intra-specific binary contaminations in yeast cultures
No full textBiocidal and inhibitory activity screening of de novo synthesized surfactants against two eukaryotic and two prokaryotic microbial species
No full textThirty-six quaternary ammonium salts, of which 28 structurally different non-commercially available surfactants, were tested to screen their biocidal and inhibitory antimicrobial activity. Their activity was compared to commercially available amphiphiles as well as to non-amphiphilic quaternary ammonium salts. As target of these compounds four microbial species were employed of which two (Saccharomyces cerevisiae and Candida albicans) were important yeast in the food and clinical environment and the other two (Escherichia coli and Listeria innocua) represented the Gram negative and positive bacteria, respec- tively. The surfactants showed the ability to kill the microbial cells in water solution and to variably hamper their growth onto agar medium. The non-amphiphilic compounds (which represent analogues of some surfactants used in this study, since they have the same head group but no hydrophobic portion) had little effect in solution and no effect against the microbial growth on plate. Amphoteric and non- amphoteric zwitterionic surfactants showed reduced biocidal activity. The most active antimicrobial agent was N-tetradecyltropinium bromide (23S) surfactant. The presence of cells did not significantly affect the ability to form micelles, as demonstrated by comparative conductometric measurements
FTIR analysis of the metabolomic stress response induced by N-alkyltropinium bromide surfactants in the yeasts Saccharomyces cerevisiae and Candida albicans
No full textThe activity of surfactants against fungal cells has been studied less than against bacteria, although the medical and industrial importance of the former is of paramount importance. In this paper the surfactant biocidal effect was measured in the yeasts Saccharomyces cerevisiae and Candida albicans with a previously described FTIR bioassay which estimates the stress level as function of the FTIR spectra variation of the cells upon exposition to the chemicals. N-tetradecyltropinium bromide was chosen as stressing agent on the basis of previous preliminary study demonstrating its ability to kill prokaryotic and especially eukaryotic cells at concentration around or over the critical micellar concentration (c.m.c.). Here we show that this surfactant is able to inactivate S. cerevisiae cells at 0.4 mM and C. albicans cells at 0.6 mM after 1 h exposition. FTIR analysis revealed that the surfactant induced metabolomics reactions of S. cerevisiae cells in the regions of amides (W2) and fatty acids (W1). In the same way C. albicans cells showed the maximum stress response in amides (W2) and mixed (W3) regions. Variations of the hydrophobic tail of this surfactant produced a reduced level of cell stress with both the 12C and 16C variants; although these two compounds were more effective in inducing cell mortality in S. cerevisiae but not in C. albicans. In conclusion, this paper has shown that, for this surfactant, the n-alkyl chain must vary between 12C and 16C and that the hydrophilic head size is not as critical as the tail length
Direct spectroscopic (FTIR) detection of intra-specific binary contaminations in yeast cultures. FEMS Yeast Research.
No full textNovel zwitterionic deep eutectic solvents from trimethylglycine and carboxylic acids: characterization of their properties and their toxicity
No full textWe report the preparation and the study of the properties of novel deep eutectic solvents (DESs) formed by zwitterionic trimethylglicine and high melting point carboxylic acids. These zwitterionic DESs are liquid at room temperature or at temperatures lower than 70 C and do not have chloride or any metal ions in their composition. These media were characterized in terms of their viscosity, conductivity, density, ionicity (via Walden plots), surface tension and thermal stability. The values observed are similar to other typical DESs, and the mixtures resulted in “poor ionic liquids” in the Walden plot. The values obtained could be correlated to the carboxylic acids' structures. The toxicity of the pure mixtures was evaluated via an FTIR-bioassay on Saccharomyces cerevisiae cells. This method allowed us to define the action of these media as dehydrating agents on eukaryotic model cells, with a mechanism highly correlated with CaCl2, a well-known dehydrating agent. The Glycolic acid/Trimethylglicine eutectic system can be considered a NADES (Natural Deep Eutectic Solvent) and resulted as the est in our set for many reasons. It is formed by natural, renewable, eco-compatible and cheap compounds (both the molecules can be derived from sugar beet) and it can be used in many applications because it has a low melting point (36 C) and it is colorless, and therefore suitable for spectroscopic measurements. For these reasons, the solubility of some alfa-L-amino acids was investigated in this DES, showing a good solubility for aromatic amino acids, which are normally scarcely soluble in water
Room temperature deep eutectic solvents of (1S)-(+)-10-camphorsulfonic acid and sulfobetaines: hydrogen bond-based mixtures with low ionicity and structure-dependent toxicity
No full textTwelve novel deep eutectic solvents (DESs) were prepared and characterized in this work. They are mixtures of (1S)-(+)-10-camphorsulfonic acid (CSA) and differently structured sulfobetaines (SBs) with aliphatic, aromatic and amphiphilic moieties. They are liquids at room temperature, their melting points span, in fact, from 5 to 19 C, so we can name these mixtures RTDESs (room temperature deep eutectic solvents). These zwitterionic DESs were characterized in terms of their viscosity, conductivity (and therefore ionicity via Walden plots), density, surface tension and toxicity on eukaryotic model cells. The collected data suggest that the interaction between CSA and the SBs can be ascribed as a hydrogen bond instead of a proton transfer, therefore they are not ionic liquids. To our knowledge, their position
on the Walden plot, in the left portion close to the diagonal, has not yet been observed for other DESs or ionic liquid systems and indicates the low ionicity of these mixtures. A FTIR-based bioassay was performed to determine the toxicity of these mixtures on eukaryotic model cells (Saccharomyces cerevisiae). The DESs showed merely a dehydrating effect on the cells, similar to that produced by CaCl2, a low cell toxicity salt. This supports these DESs as promising green media. Amphiphilic SBs DESs showed a stronger effect on the cells and a structure-activity trend can be described for this class. A preliminary study on the use of these novel DESs as Brønsted catalyst media was accomplished by the use of one of them in chalcone synthesis, which showed promising catalytic and recycling capabilities
Influence of cell parameters in Fourier transform infrared spectroscopy analysis of whole yeast cells
No full textSearching for Related Descriptors Among Different Datasets: A New Strategy Implemented by the R Package “Dadi”
No full textCentrality of Objects in a Multidimensional Space and its Effects on Distance-Based Biological Classifications
No full textTypology is bases on the concept that one individual (the type) can represent the whole group. In yeast taxonomy the type strain is the representative of the whole species and is considered an important tool for classification. Although the evolutionary, phylogenetic and biological species concept are in contrast with this approach, the International Codes of nomenclature still use typology, which remains one of the most operative systems. These incongruities demand a multidisciplinary investigation on the nature of the type, its characteristics and the possibility of the type to be defined on the basis of a shareable criterion. In this paper we present an approach to the problem of type centrality based on mathematical demonstrations and numerical examples. This paper intended to show the possibilities offered to bioinformatics research by the implementation of multidisciplinary approaches in biology and in proposing a general approach to the definition of the type representing any sort of set, described with multiple descriptors
Phenotypic and molecular diversity of Meyerozyma guilliermondii strains isolated from food and other environmental niches, hints for an incipient speciation
No full textMeyerozyma guilliermondii is a yeast species widely isolated from several natural environments and from fruit; in medical microbiology it is known as the teleomorph of the opportunistic pathogen Candida guilliermondii, which causes about 2% of the human blood infections. This yeast is also promising in a variety of biotechnological applications as vitamins production and post-harvest control. The question if isolates from different sources are physiologically and genetically similar, or if the various environments induced significant differences, is crucial for the understanding of this species structure and to select strains appropriate for each application. This question was addressed using LSU and ITS sequencing for taxonomic assignment, i-SSR (GACA4) for the molecular characterization and FTIR for the metabolomic fingerprint. All data showed that fruit and environmental isolates cluster separately with a general good agreement between metabolomics and molecular analysis. An additional RAPD analysis was able to discriminate strains according to the isolation position within the pineapple fruit. Although all strains are members of the M. guilliermondii species according to the current standards, the distribution of large variability detected suggests that some specialization occurred in the niches inhabited by this yeast and that food related strains can be differentiated from the medical isolates
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