1,721,226 research outputs found
Field releases of genetically modified microorganisms used as PGPR: an experience of two decades.
No full textGrowth of Staphylococcus aureus and enterotoxin production in fresh egg pasta
No full textThis study investigated the growth of enterotoxin-producing Staphylococcus aureus and time–temperature combinations necessary for enterotoxin production in artificially and naturally contaminated fresh egg pasta. Egg pasta (35 ± 1 g) inoculated with three strains of enterotoxin-producing S. aureus at two different concentrations (103 CFU/g and 10 CFU/g) were incubated at 20 °C, 30 °C and 37 °C for 34 h. Industrial samples were S. aureus was naturally present at a concentration of 2.5 x 102 CFU/g were incubated under the same conditions. Enterotoxin was produced in all samples inoculated with the three strains of S. aureus incubated at 20 °C for 24 h or 30 °C for 10 h. No enterotoxin was produced in the naturally contaminated samples, even if the S. aureus concentration reached 106–107 CFU/g by the end of the experiment (34 h) indicating that the Staphylococci isolated in the production line were not enterotoxin-producing strains. Practical application: This research focused on the growth and enterotoxin production of Staphylococcus aureus naturally present on fresh egg pasta produced in an industrial line or artificially inoculated with three different strains of this bacterium. Our results confirmed that the staphylococci, naturally contaminating the fresh egg pasta during the production, were not enterotoxin-producing. However, the results obtained using enterotoxin producing strains show that this kind of product can support the development of theses bacteria and enterotoxin production. Therefore, these results should be useful to fresh pasta manufacturers and aid them in setting up their control measures in the Hazard Analysis and Critical Control Point in order to manage the microbial safety of the fresh egg pasta products
Le Biotecnologie Microbiche Ambientali Di Vecchia e Nuova Generazione: Principali Applicazioni e Problematiche.
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Innately robust yeast strains isolated from grape marc have a great potential for lignocellulosic ethanol production
Full text linkBioethanol from lignocellulose is an attractive alternative to fossil fuels, and Saccharomyces cerevisiae is the most important ethanol producer. However, yeast cells are challenged by various environmental stresses during ethanol production on an industrial scale, and robust strains with a high tolerance to inhibitors, temperature and osmolality are needed for the effective feasibility of lignocellulosic ethanol. To search for such innately more resistant yeast, we selected grape marc as an extreme environment due to limited nutrients, exposure to solar radiation, temperature fluctuations, weak acids and ethanol. Using a temperature of 40 A degrees C as the key selection criterion, we isolated 120 novel S. cerevisiae strains from grape marc and found high ethanol yields (up to 92 % of the theoretical maximum) when inoculated at 40 A degrees C in minimal media with a high sugar concentration. For the first time, this work assessed yeast tolerance to inhibitors at 40 A degrees C, and the newly isolated yeast strains displayed interesting abilities to withstand increasing levels of single inhibitors or cocktails containing a mixture of inhibitory compounds. The newly isolated strains showed significantly higher fermentative abilities and tolerance to inhibitors than the industrial and commercial benchmark S. cerevisiae strains. The strong physiological robustness and fitness of a few of these S. cerevisiae yeast strains support their potential industrial application and encourage further studies in genetic engineering to enhance their ethanol performance in terms of rate and yield through the co-fermentation of all available carbon sources
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