J Vives-Rego

Polytechnic University of Catalonia, Barcelona, Catalonia, Spain

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Publications (62)111.68 Total impact

  • X Portell, M Ginovart, R Carbó, J Vives-Rego
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    ABSTRACT: We applied electric particle analysis, light diffraction and flow cytometry to obtain information on the morphological changes during the stationary phase of Saccharomyces cerevisiae. The reported analyses of S. cerevisiae populations were obtained under two different conditions, aerobic and microaerophilic, at 27°C. The samples analysed were taken at between 20 and 50 h from the beginning of culture. To assist in the interpretation of the observed distributions a complexity index was used. The aerobically grown culture reached significantly greater cell density. Under these conditions, the cell density experienced a much lower reduction (3%) compared with the microaerophilic conditions (30%). Under aerobic conditions, the mean cell size determined by both electric particle analysis and light diffraction was lower and remained similar throughout the experiment. Under microaerophilic conditions, the mean cell size determined by electric particle analysis decreased slightly as the culture progressed through the stationary phase. Forward and side scatter distributions revealed two cell subpopulations under both growth conditions. However, in the aerobic growing culture the two subpopulations were more separated and hence easier to distinguish. The distributions obtained with the three experimental techniques were analysed using the complexity index. This analysis suggested that a complexity index is a good descriptor of the changes that take place in a yeast population in the stationary phase, and that it aids in the discussion and understanding of the implications of these distributions obtained by these experimental techniques.
    Journal of Industrial Microbiology 01/2011; 38(1):141-51. · 1.80 Impact Factor
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    ABSTRACT: Data from electric particle analysis, light diffraction and flow cytometry analysis provide information on changes in cell morphology. Here, we report analyses of Saccharomyces cerevisiae populations growing in a batch culture using these techniques. The size distributions were determined by electric particle analysis and by light diffraction in order to compare their outcomes. Flow cytometry parameters forward (related to cell size) and side (related to cell granularity) scatter were also determined to complement this information. These distributions of yeast properties were analysed statistically and by a complexity index. The cell size of Saccharomyces at the lag phase was smaller than that at the beginning of the exponential phase, whereas during the stationary phase, the cell size converged with the values observed during the lag phase. These experimental techniques, when used together, allow us to distinguish among and characterize the cell size, cell granularity and the structure of the yeast population through the three growth phases. Flow cytometry patterns are better than light diffraction and electric particle analysis in showing the existence of subpopulations during the different phases, especially during the stationary phase. The use of a complexity index in this context helped to differentiate these phases and confirmed the yeast cell heterogeneity.
    FEMS Yeast Research 09/2010; 11(1):18-28. · 2.46 Impact Factor
  • Josep Vives-Rego
    Environmental Forensics 08/2010; September 2004(Vol. 5):123-124. · 0.65 Impact Factor
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    ABSTRACT: Individual-based modelling (IbM) has become a fully incorporated part of predictive microbiology methodologies in the last decade. Previous studies of bacterial culture growth cycle with the IbM simulator INDISIM analysed the evolution of bacterial biomass distribution during the different phases of growth. The predicted forward shift during lag, stability during exponential and backward shift when entering the stationary phase have been experimentally observed in an Escherichia coli batch culture by means of flow cytometry and particle size analysis measurements. In addition, the experimental results were analysed using the product distance, a mathematical tool developed to assess the evolution of cell size distribution. These results confirmed the assumptions about the bacterial lag phase made by INDISIM. Moreover, flow cytometry and particle analysis methods were shown to be useful experimental techniques in combination with IbM simulations when studying the evolution of individual properties during the bacterial growth cycle. This is essential in order to provide a new and consistent interpretation of the dynamics and heterogeneity of cell biomass during the growth cycle.
    African journal of microbiology research 04/2010; 4:400-407. · 0.54 Impact Factor
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    ABSTRACT: We report a skew-Laplace statistical analysis of both flow cytometry scatters and cell size from microbial strains primarily grown in batch cultures, others in chemostat cultures and bacterial aquatic populations. Cytometry scatters best fit the skew-Laplace distribution while cell size as assessed by an electronic particle analyzer exhibited a moderate fitting. Unlike the cultures, the aquatic bacterial communities clearly do not fit to a skew-Laplace distribution. Due to its versatile nature, the skew-Laplace distribution approach offers an easy, efficient, and powerful tool for distribution of frequency analysis in tandem with the flow cytometric cell sorting.
    International Journal of Microbiology 01/2010; 2010:191585.
  • J. Martínez, J. Vives-Rego, Y. Soto, M. Bianchi
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    ABSTRACT: The toxicity of Cu++, Ni++, and linear alkylbenzene sulfonate to the bacterioplankton in the Rhóne River plume (Mediterranean Sea) was assessed by [3H]thymidine incorporation into trichloroacetic acid-insoluble material. This method proved useful to evaluate the toxic effect of three common pollutants to the natural bacterial population in a system with permanent mixtures of fresh and sea water. An important variability in the toxicity has been detected irrespective of bacterial density or activity. The variations in toxicity were associated with the changes of salinity, particulate matter, and nutrients in the river plume.
    Environmental Toxicology and Chemistry 10/2009; 10(5):641 - 647. · 2.62 Impact Factor
  • Jordi Ferrer, Clara Prats, Daniel López, Josep Vives-Rego
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    ABSTRACT: Predictive microbiology is the area of food microbiology that attempts to forecast the quantitative evolution of microbial populations over time. This is achieved to a great extent through models that include the mechanisms governing population dynamics. Traditionally, the models used in predictive microbiology are whole-system continuous models that describe population dynamics by means of equations applied to extensive or averaged variables of the whole system. Many existing models can be classified by specific criteria. We can distinguish between survival and growth models by seeing whether they tackle mortality or cell duplication. We can distinguish between empirical (phenomenological) models, which mathematically describe specific behaviour, and theoretical (mechanistic) models with a biological basis, which search for the underlying mechanisms driving already observed phenomena. We can also distinguish between primary, secondary and tertiary models, by examining their treatment of the effects of external factors and constraints on the microbial community. Recently, the use of spatially explicit Individual-based Models (IbMs) has spread through predictive microbiology, due to the current technological capacity of performing measurements on single individual cells and thanks to the consolidation of computational modelling. Spatially explicit IbMs are bottom-up approaches to microbial communities that build bridges between the description of micro-organisms at the cell level and macroscopic observations at the population level. They provide greater insight into the mesoscale phenomena that link unicellular and population levels. Every model is built in response to a particular question and with different aims. Even so, in this research we conducted a SWOT (Strength, Weaknesses, Opportunities and Threats) analysis of the different approaches (population continuous modelling and Individual-based Modelling), which we hope will be helpful for current and future researchers.
    International journal of food microbiology 02/2009; 134(1-2):2-8. · 3.01 Impact Factor
  • J. MARTINEZ, J. GARCIA, J. VIVES-REGO
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    ABSTRACT: In the terminal part of the Ebro river, bacterial production and mortality have been studied. Bacterial production was estimated by the thymidine incorporation method and from estimates of growth rate. Bacterial mortality and grazing were studied using differential filtration of a 3H-labelled population. Production was estimated as about 0.15 times 109 bacteria/l/h and total mortality was about 0.016/h. Grazing accounted for about 56% of the total mortality processes.
    Letters in Applied Microbiology 06/2008; 4(6):145 - 147. · 1.63 Impact Factor
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    ABSTRACT: The lag phase is the initial phase of a culture that precedes exponential growth and occurs when the conditions of the culture medium differ from the pre-inoculation conditions. It is usually defined by means of cell density because the number of individuals remains approximately constant or slowly increases, and it is quantified with the lag parameter lambda. The lag phase has been studied through mathematical modelling and by means of specific experiments. In recent years, Individual-based Modelling (IbM) has provided helpful insights into lag phase studies. In this paper, the definition of lag phase is thoroughly examined. Evolution of the total biomass and the total number of bacteria during lag phase is tackled separately. The lag phase lasts until the culture reaches a maximum growth rate both in biomass and cell density. Once in the exponential phase, both rates are constant over time and equal to each other. Both evolutions are split into an initial phase and a transition phase, according to their growth rates. A population-level mathematical model is presented to describe the transitional phase in cell density. INDividual DIScrete SIMulation (INDISIM) is used to check the outcomes of this analysis. Simulations allow the separate study of the evolution of cell density and total biomass in a batch culture, they provide a depiction of different observed cases in lag evolution at the individual-cell level, and are used to test the population-level model. The results show that the geometrical lag parameter lambda is not appropriate as a universal definition for the lag phase. Moreover, the lag phase cannot be characterized by a single parameter. For the studied cases, the lag phases of both the total biomass and the population are required to fully characterize the evolution of bacterial cultures. The results presented prove once more that the lag phase is a complex process that requires a more complete definition. This will be possible only after the phenomena governing the population dynamics at an individual level of description, and occurring during the lag and exponential growth phases, are well understood.
    Journal of Theoretical Biology 06/2008; 252(1):56-68. · 2.35 Impact Factor
  • J. Martinez, M. Riera, J. Lalucat, J. Vives-Rego
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    ABSTRACT: The incorporation of tritiated ([3H]-) thymidine into DNA by axenic laboratory cultures of a common marine blue-green algae and two marine eukaryotic algae was measured. Tritiated thymidine was incorporated into the cold TCA fraction of the cyanobacterium and eukaryote algae. However, only in the culture of cyanobacterium was the thymidine consistently incorporated into DNA. Considering the usual algal densities in natural habitats, thymidine concentrations and incubation times, our data do not preclude the use of thymidine incorporation in bacterial production studies in marine environments.
    Letters in Applied Microbiology 03/2008; 8(4):135 - 138. · 1.63 Impact Factor
  • J. Vives-Rego, R. López-Amorós, J. Comas
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    ABSTRACT: Flow cytometry was used to study starvation of Escherichia coli in artificial sea water. Flow cytometric narrow-angle light scatter was compared and assessed in relation to the cell sizes obtained by scanning electron microscopy at low temperature, and by image analysis. A correlation between narrow-angle light scatter and cell size was not observed, although an acceptable correlation (γ= -0.845) between narrow-angle light scatter and the starvation period was observed. On the other hand, the distribution of narrow-angle light scatter at any given moment of culture is asymmetric and may be associated with the cell size distribution at the specific moment of starvation.
    Letters in Applied Microbiology 03/2008; 19(5):374 - 376. · 1.63 Impact Factor
  • J. Martínez, J. Vives-Rego
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    ABSTRACT: The impact of urban and industrial wastes on marine bacteria was assessed by thymidine incorporation and bacterial mortality. The results indicate that heavy metals are highly toxic to the marine bacteria, while alkyl benzene sulfonate exhibits a moderate biotoxicity. The lyophilized wastes are, however, only mildly toxic to the marine bacteria. In general, the bacterial mortality rate is increased with the industrial waste loading.
    Environmental Toxicology and Water Quality 06/2006; 3(1):33 - 40.
  • I Barcina, P Lebaron, J Vives-Rego
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    ABSTRACT: The survival of allochthonous bacteria in aquatic systems is affected by biotic and abiotic environmental factors. Grazing by protozoa is one of the main biological processes that control allochthonous bacterial density. Its extent depends on the concentration of bacteria and the digestion capacity of the grazer. The physiological state of bacteria is affected by multiple physicochemical stresses, to which they respond by entering a dormant, viable but non-culturable state. Starved bacteria show a tendency to shrink, and a generally enhanced resistance to heat, oxidative and osmotic shock is observed. Nutrient scarcity, temperature, osmotic stress and visible light seem to be the abiotic factors that most negatively influence survival. The negative effect of light upon the culturability of enterobacteria in aquatic systems has long been recognized. In relation to the influence of plasmids on bacterial survival, heterogeneous and contradictory results have been reported. Some authors reported that plasmid-bearing strains can survive as well as their wild-type counterparts or even better, whereas in other reports the effects of various plasmids on the survival of their hosts were very variable. Plasmid transfer could be affected by the physiological status of donors and recipients during survival. Flow cytometry is a recent approach with great potential, especially for assessing the heterogeneity of cell size, metabolic state and molecular content in the population.
    FEMS Microbiology Ecology 01/2006; 23(1):1 - 9. · 3.56 Impact Factor
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    ABSTRACT: Viable, total and metabolically active bacteria were determined during linear alkylbenzene sulfonate degradation in coastal seawater. Viable bacteria were estimated by plate counts on marine agar media while the total and metabolically active bacteria were determined with the nucleic acid stain SYTO-13 and the tetrazolium salt 5-cyano-2,3-ditolyl tetrazolium chloride, respectively, in double stain procedures analyzed by flow cytometry. The double stain SYTO-13/5-cyano-2,3-ditolyl tetrazolium chloride is a rapid and simple method that discriminates bacterioplankton populations according to nucleic acid content and formazan formation. Linear alkylbenzene sulfonate degradation was monitored by high-performance liquid chromatography analysis. Bacterioplankton degraded linear alkylbenzene sulfonate by growing to communities with a high percentage of viable and metabolically active bacteria. The bacteria produced were rapidly grazed by protozoa; however, the grazing took place mostly on metabolically active cells, which were larger than the rest of the population.
    FEMS Microbiology Ecology 01/2006; 27(1):33 - 42. · 3.56 Impact Factor
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    Olga Julià, Josep Vives-Rego
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    ABSTRACT: The application of flow cytometry and skew-Laplace statistical analysis to assess cellular heterogeneity in Gram-negative axenic cultures is reported. In particular, fit to the log-skew-Laplace distribution for cellular side scatter or 'granulosity' is reported, and a number of theoretical and applied issues are considered in relation to the biological significance of this fit.
    Microbiology 04/2005; 151(Pt 3):749-55. · 2.85 Impact Factor
  • M Moragues, J Comas-Riu, J Vives-Rego
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    ABSTRACT: We report a novel application of calcein-acetomethyl ester in flow cytometry for rapid estimation of the number of G+-bacteria in rodent feces (Apodemus sylvaticus and Mus sp.f. muridae). We also use the combined application of flow cytometry and Syto-13 or Sypro Orange staining to count rapidly the total bacterial population and to describe bacterial subpopulations in the intestine.
    Folia Microbiologica 02/2004; 49(5):587-90. · 0.79 Impact Factor
  • J Vives-Rego, O Resina, J Comas, G Loren, O Julià
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    ABSTRACT: Histogram comparison and meaningful statistics in flow cytometry is probably the most widely encountered mathematical problem in flow cytometry. Ideally, a test for determining the statistical equality or difference of flow cytometric distributions will identify the significant differences or similarities of the obtained histograms. This situation is of particular interest when flow cytometry is used to study the heterogeneity of axenic bacterial populations. We have statistically measured the heterogeneity of successive cytometric measures, the modifications produced after 20 transfers from the same culture, and the differences between 20 subcultures of identical origin. The heterogeneity of the bacterial populations and the similarity of the obtained 360 histograms were analysed by standard statistical methods. We have studied bacterial axenic cultures in order to detect, quantify and interpret their cytometric heterogeneity, and to assess intrinsic differences and differences produced by laboratory manipulations. We concluded that the standard axenic cultures have a considerable intrinsic cellular and molecular heterogeneity. We suggest that the heterogeneity we have detected basically has two origins: cell size diversity and cell cycle variations.
    Journal of Microbiological Methods 05/2003; 53(1):43-50. · 2.16 Impact Factor
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    ABSTRACT: Abstract Methods that quickly assess microbial density and aggregation in soil and sediments are needed in environmental microbiology. We report a flow cytometry method that uses the green and orange emission of the fluorochrome SYTO-13 to discriminate between bacteria and clay-humic acid particles. This approach distinguishes single or clustered bacteria, and clusters of bacteria and abiotic particles during the growth of the biosurfactant-producing strain Pseudomonas aeruginosa 19SJ on solid phenanthrene in the presence of humic acid-clay complexes.
    FEMS Microbiology Ecology 03/2003; 43(1):55-61. · 3.56 Impact Factor
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    ABSTRACT: A flow cytometric protocol to detect and enumerate heterotrophic nanoflagellates (HNF) in enriched waters is reported. At present, the cytometric protocols that allow accurate quantification of bacterioplankton cannot be used to quantify protozoa for the following reasons: i) the background produced by the bacterial acquisitions does not allow the discrimination of protozoa at low abundance, ii) since the final protozoan fluorescence is much higher than the bacterioplankton fluorescence (more than 35 fold) the protozoa acquisitions lie outside the range. With an increase in the fluorescence threshold and a reduction of the fluorescence detector voltage, low fluorescence particles (bacteria) are beneath the detection limits and only higher fluorescence particles (most of them heterotrophic nanoflagellates) are detected. The main limitation for the application of the cytometric protocol developed is that a ratio of bacteria/HNF below 1000 is needed. At higher ratios, the background of larger cells of bacterioplankton makes it difficult to discriminate protozoa. The proposed protocol has been validated by epifluorescence microscopy analyzing both a mixed community and two single species of HFN: Rhynchomonas nasuta and Jakoba libera. Taking into account the required bacteria/HNF ratio cited above, the results provide evidence that the flow cytometric protocol reported here is valid for counting mixed communities of HNF in enriched seawater and in experimental micro or mesocosms. In the case of single species of HNF previous knowledge of the biological characteristics of the protist and how they can affect the effectiveness of the flow cytometric count is necessary.
    Systematic and Applied Microbiology 05/2002; 25(1):100-8. · 3.29 Impact Factor
  • J Comas-Riu, Josep Vives-Rego
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    ABSTRACT: Formation of bacterial endospores is a basic process in Gram-positive bacteria and has implications for health, industry and the environment. Flow cytometry offers a practical alternative for the rapid detection, enumeration and characterization of bacterial endospores. Paenibacillus polymyxa was chosen for this study because its spores cause sporangium deformation and have thick walls with a star-shaped section. Sporulating populations were analysed with a particle analyser and a flow cytometer after labelling with propidium iodide and Syto-13. Flow cytometric detection of single spores was confirmed by optical and scanning electron microscopy after cell sorting. Four cell sub-populations were cytometrically detected in P. polymyxa cultures grown in liquid sporulation medium. Two sub-populations consisted of vegetative cells differing in both morphology and viability; the other two sub-populations consisted of spores differing in their viability. This work has shown that flow cytometry is a simple and fast method (less than 15 minutes for sample preparation and analysis) for the study of the sporulation in P. polymyxa. The use of this technique allowed both detection and quantification of sporulation inside a culture, and distinguished cells that differed in viability despite being morphologically identical under microscopic observation. Flow cytometry has been proved to be a valuable tool for the analysis of sporulation in P. polymyxa cultures, with the unique capacity of distinguishing between endospores and vegetative cells, and between live and dead cells, in the same analysis. An important percentage of non-viable endospores has been found in aged cultures using this method.
    Journal of Applied Microbiology 02/2002; 92(3):475-81. · 2.20 Impact Factor

Publication Stats

1k Citations
111.68 Total Impact Points

Institutions

  • 2008–2011
    • Polytechnic University of Catalonia
      • • Department of Agri-Food Engineering and Biotechnology (DEAB)
      • • Department of Physics and Nuclear Engineering (FEN)
      Barcelona, Catalonia, Spain
  • 1986–2011
    • University of Barcelona
      • • Department of Microbiology
      • • Department of Probability, Logic and Statistics
      • • Departament d'Estadística
      • • Facultad de Biología
      Barcino, Catalonia, Spain
  • 2001
    • Spanish National Research Council
      • Department of Chemical and Surfactants Technology
      Madrid, Madrid, Spain
  • 1987
    • Université Libre de Bruxelles
      • Laboratory of Aquatic Systems Ecology
      Bruxelles, Brussels Capital Region, Belgium