Assessing the inhibitory activity of culture supernatants against foodborne pathogens of two psychrotrophic bacteria isolated from river trout.

There is a need for new natural products with antimicrobial activity to treat multidrug resistant bacteria that can cause human illness. Some of them are foodborne pathogens. Two different Gram-negative psychrotrophic strains were isolated from healthy trout river samples (Salmo trutta). Based on phenotypic characterization, proteomics, genotyping and phylogenetic analyses of 16 rRNA gene, strains TCPS12 and TCPS13 were identified as Shewanella baltica and Pseudomonas fragi, respectively. Both of them produced an exopolysaccharide that showed antimicrobial activity against four foodborne pathogens. P. fragi supernatant (AS13) showed higher antimicrobial activity than S. baltica supernatant (AS12) against all tested pathogens. The stability of the antimicrobial activity of AS13 was assessed against Enterococcus faecalis ATCC 29212 under different conditions. This solution was stable when exposed for 30 min to temperatures ranging from 40 to 100 °C. In addition, it retained its activity within a pH range of 2-8 during 2 h of incubation, showing higher activity at pH 6. Serine proteases and α-amylase inactivated significantly the antimicrobial activity of AS13, suggesting that the active molecule could most likely be a glycoprotein. These products are interesting for their possible application as biopreservatives in the food industry.

Exploration of the Drosophila buzzatii transposable element content suggests underestimation of repeats in Drosophila genomes.

BACKGROUND: Many new Drosophila genomes have been sequenced in recent years using new-generation sequencing platforms and assembly methods. Transposable elements (TEs), being repetitive sequences, are often misassembled, especially in the genomes sequenced with short reads. Consequently, the mobile fraction of many of the new genomes has not been analyzed in detail or compared with that of other genomes sequenced with different methods, which could shed light into the understanding of genome and TE evolution. Here we compare the TE content of three genomes: D. buzzatii st-1, j-19, and D. mojavensis. RESULTS: We have sequenced a new D. buzzatii genome (j-19) that complements the D. buzzatii reference genome (st-1) already published, and compared their TE contents with that of D. mojavensis. We found an underestimation of TE sequences in Drosophila genus NGS-genomes when compared to Sanger-genomes. To be able to compare genomes sequenced with different technologies, we developed a coverage-based method and applied it to the D. buzzatii st-1 and j-19 genome. Between 10.85 and 11.16 % of the D. buzzatii st-1 genome is made up of TEs, between 7 and 7,5 % of D. buzzatii j-19 genome, while TEs represent 15.35 % of the D. mojavensis genome. Helitrons are the most abundant order in the three genomes. CONCLUSIONS: TEs in D. buzzatii are less abundant than in D. mojavensis, as expected according to the genome size and TE content positive correlation. However, TEs alone do not explain the genome size difference. TEs accumulate in the dot chromosomes and proximal regions of D. buzzatii and D. mojavensis chromosomes. We also report a significantly higher TE density in D. buzzatii and D. mojavensis X chromosomes, which is not expected under the current models. Our easy-to-use correction method allowed us to identify recently active families in D. buzzatii st-1 belonging to the LTR-retrotransposon superfamily Gypsy.

Ultrastructural changes of sparkling wine lees during long-term aging in real enological conditions.

Ultrastructural changes of lees of three series of sparkling wines produced using the traditional method during long-term aging (4 years) were assessed by high-pressure freezing in combination with transmission electron microscopy. The stratified structure of the cell wall disappeared throughout aging. After 18 months, the microfibrous material of the cell wall appeared more diffuse and the amorphous midzone of the inner wall layer was progressively degraded. From 30 months onward, the cell wall consisted of a tangled structure of fibers. In spite of these changes, the cell wall of yeasts remained unbroken at 48 months of wine aging. Cell membrane breakage was observed for the first time in lees of Saccharomyces cerevisiae. An increase in the thickness of the periplasmic space owing to plasmolysis and of the number of cells with less cytoplasmic content was observed during aging. Morphological evidence of microautophagy was detected for the first time in S. cerevisiae in enological conditions.

Increase of burnout among emergency department professionals due to emotional exhaustion during the SARS-Cov2 pandemic: Evolution from 2016 to 2021.

The objective is to establish there have been any significant changes in the evolution of levels of burnout and empathy at the different Emergency Department in our region, bearing the severe acute respiratory syndrome coronavirus 2 pandemic. This cross-sectional observational study was conducted in a healthy region between November 2020 and January 2021. Lleida emergency care centers. All the doctors and nurses of the health were contacted by email. Empathy was measured using the Spanish version of the Jefferson scale of physician empathy. Burnout was measured using the Maslach Burnout Inventory (MBI) in the version validated in Spanish. Sociodemographic data were also recorded. We compared the data with 2016 results. A total of 159 professionals agreed to participate in this study. A significant increase in the MBI score was observed in the 2020 to 2021 sample (39.5 vs 49.7), mostly due to an increase in the MBI-EE (21.5 vs 28.5), as well as an increase in the Jefferson scale of physician empathy score (112 vs 116). (P = .039). There were no differences when analyzing the association between professions (nurses or doctors) or years worked, burnout, and empathy. For 2020 to 2021, the 41 to 50 years age group showed the highest burnout (MBI score). Emergency department practitioners suffered more burnout compared to 2016, especially due to emotional exhaustion (P < .001). Despite practitioners' improved degree of empathy, which had been described as being preventative against burnout, during the COVID-19 pandemic, over-involvement may have led to empathic stress and emotional exhaustion, giving rise to greater burnout.

Flow cytometry applications in the food industry.

Flow cytometry has become a valuable tool in food microbiology. By analysing large numbers of cells individually using light-scattering and fluorescence measurements, this technique reveals both cellular characteristics and the levels of cellular components. Flow cytometry has been developed to rapidly enumerate microorganisms; to distinguish between viable, metabolically active and dead cells, which is of great importance in food development and food spoilage; and to detect specific pathogenic microorganisms by conjugating antibodies with fluorochromes, which is of great use in the food industry. In addition, high-speed multiparametric data acquisition, analysis and cell sorting, which allow other characteristics of individual cells to be studied, have increased the interest of food microbiologists in this technique. This mini-review gives an overview of the principles of flow cytometry and examples of the application of this technique in the food industry.

Use of tocopherol extract and different nitrite sources and starter cultures in the production of organic botifarra catalana, a cooked cured sausage.

This research evaluates the effects of adding a tocopherol mix (0 or 200 mg/kg), two nitrite sources (sodium nitrite or a nitrate-rich vegetable concentrate) and the use of Staphylococcus carnosus together with fermentation types that varied in temperature (12 h at 4 ℃ or 16 ℃) on different quality parameters and acceptability of cooked cured sausages after vacuum packing and storage at 4 ℃ for 120 days. In the presence of S. carnosus, residual nitrate and nitrite levels were reduced. Sausages containing vegetable concentrates and without S. carnosus resulted in higher amounts of residual nitrate and lower curing efficiency. The lowest values in redness and acceptability were observed in those sausages without starter cultures. The addition of tocopherols had no effect on oxidative status and susceptibility to oxidation. However, the highest amount of hydroperoxides was related with nitrite decreased formation. Overall, vegetable concentrates can be used as curing agents if fermentation with a nitrate-reducing starter culture is allowed.

Genomics of ecological adaptation in cactophilic Drosophila.

Cactophilic Drosophila species provide a valuable model to study gene-environment interactions and ecological adaptation. Drosophila buzzatii and Drosophila mojavensis are two cactophilic species that belong to the repleta group, but have very different geographical distributions and primary host plants. To investigate the genomic basis of ecological adaptation, we sequenced the genome and developmental transcriptome of D. buzzatii and compared its gene content with that of D. mojavensis and two other noncactophilic Drosophila species in the same subgenus. The newly sequenced D. buzzatii genome (161.5 Mb) comprises 826 scaffolds (>3 kb) and contains 13,657 annotated protein-coding genes. Using RNA sequencing data of five life-stages we found expression of 15,026 genes, 80% protein-coding genes, and 20% noncoding RNA genes. In total, we detected 1,294 genes putatively under positive selection. Interestingly, among genes under positive selection in the D. mojavensis lineage, there is an excess of genes involved in metabolism of heterocyclic compounds that are abundant in Stenocereus cacti and toxic to nonresident Drosophila species. We found 117 orphan genes in the shared D. buzzatii-D. mojavensis lineage. In addition, gene duplication analysis identified lineage-specific expanded families with functional annotations associated with proteolysis, zinc ion binding, chitin binding, sensory perception, ethanol tolerance, immunity, physiology, and reproduction. In summary, we identified genetic signatures of adaptation in the shared D. buzzatii-D. mojavensis lineage, and in the two separate D. buzzatii and D. mojavensis lineages. Many of the novel lineage-specific genomic features are promising candidates for explaining the adaptation of these species to their distinct ecological niches.

A divergent P element and its associated MITE, BuT5, generate chromosomal inversions and are widespread within the Drosophila repleta species group.

The transposon BuT5 caused two chromosomal inversions fixed in two Drosophila species of the repleta group, D. mojavensis and D. uniseta. BuT5 copies are approximately 1-kb long, lack any coding capacity, and do not resemble any other transposable element (TE). Because of its elusive features, BuT5 has remained unclassified to date. To fully characterize BuT5, we carried out bioinformatic similarity searches in available sequenced genomes, including 21 Drosophila species. Significant hits were only recovered for D. mojavensis genome, where 48 copies were retrieved, 22 of them approximately 1-kb long. Polymerase chain reaction (PCR) and dot blot analyses on 54 Drosophila species showed that BuT5 is homogeneous in size and has a widespread distribution within the repleta group. Thus, BuT5 can be considered as a miniature inverted-repeat TE. A detailed analysis of the BuT5 hits in D. mojavensis revealed three partial copies of a transposon with ends very similar to BuT5 and a P-element-like transposase-encoding region in between. A putatively autonomous copy of this P element was isolated by PCR from D. buzzatii. This copy is 3,386-bp long and possesses a seven-exon gene coding for an 822-aa transposase. Exon-intron boundaries were confirmed by reverse transcriptase-PCR experiments. A phylogenetic tree built with insect P superfamily transposases showed that the D. buzzatii P element belongs to an early diverging lineage within the P-element family. This divergent P element is likely the master transposon mobilizing BuT5. The BuT5/P element partnership probably dates back approximately 16 Ma and is the ultimate responsible for the generation of the two chromosomal inversions in the Drosophila repleta species group.

Effect of fermentation time and vegetable concentrate addition on quality parameters of organic Botifarra Catalana, a cured-cooked sausage.

The effects of the addition of two different sources of nitrite (pure NaNO2 or a nitrate-rich vegetable concentrate) and three different fermentation times with nitrate-reducing cultures (6, 12, or 24 h at 16 °C) on microbial counts, pH, residual nitrate and nitrite amounts, and susceptibility to oxidation of botifarra catalana sausage were studied. Moreover, curing efficiency, color, tocopherol and tocotrienol contents, oxidative status, and consumer acceptability of these sausages were assessed after vacuum packaging and storage at 4 °C for up to 180 days. Residual nitrate and nitrite amounts were lower than the limits established by the European Union for organic meat products. Longer periods of fermentation produced higher meat curing efficiency ratios, whereas consumer acceptability scores were highest for sausages with added vegetable concentrate. Storage of the sausages caused small quality changes. Therefore, these results indicate that vegetable concentrate is a useful alternative for organic cured-cooked meat products.

Effect of tocopherol extract, Staphylococcus carnosus culture, and celery concentrate addition on quality parameters of organic and conventional dry-cured sausages.

The effects of the addition to sausage mix of tocopherols (200 mg/kg), a conventional starter culture with or without Staphylococcus carnosus, celery concentrate (CP) (0.23% and 0.46%), and two doses of nitrate (70 and 140 mg/kg expressed as NaNO(3)) on residual nitrate and nitrite amounts, instrumental CIE Lab color, tocol content, oxidative stability, and overall acceptability were studied in fermented dry-cured sausages after ripening and after storage. Nitrate doses were provided by nitrate-rich CP or a chemical grade source. The lower dose complies with the EU requirements governing the maximum for ingoing amounts in organic meat products. Tocopherol addition protected against oxidation, whereas the nitrate dose, nitrate source, or starter culture had little influence on secondary oxidation values. The residual nitrate and nitrite amounts found in the sausages with the lower nitrate dose were within EU-permitted limits for organic meat products and residual nitrate can be further reduced by the presence of the S. carnosus culture. Color measurements were not affected by the CP dose. Product consumer acceptability was not affected negatively by any of the factors studied. As the two nitrate sources behaved similarly for the parameters studied, CP is a useful alternative to chemical ingredients for organic dry-cured sausage production.

Insensitivity of leptogenesis with flavor effects to low energy leptonic CP violation.

If the baryon asymmetry of the Universe is produced by leptogenesis, CP violation is required in the lepton sector. In the seesaw extension of the standard model with three hierarchical right-handed neutrinos, we show that the baryon asymmetry is insensitive to the Pontecorvo-Maki-Nagakawa-Sakata phases: thermal leptogenesis can work for any value of the observable phases. This result was well known when there were no flavor effects in leptogenesis; we show that it remains true when flavor effects are included.

A new bioassay method for quantitative analysis of tetracyclines.

A new method is described for quantitative analysis of tetracycline, based on the decrease in external pH of bacterial suspensions after the addition of a glucose pulse. The decrease in external pH of these suspensions was inversely proportional to the concentration of tetracycline. The correlation coefficient of standard response lines derived from the bioassay was 0.99. Tetracycline potency was determined in six tetracycline HCl samples by the sugar pulse bioassay and a turbidimetric method. The turbidimetric assay result varied from the glucose-pulse data by no more than 7 and 3% at 3 and 7 min, respectively. The procedure is rapid, precise and quantitative, and requires minimal preparation and use of media, with savings in laboratory resources and time.