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Listeria monocytogenes is an important pathogen responsible for listeriosis, a serious foodborne illness associated with high mortality rates. Therefore, L. monocytogenes is considered a challenge for the food industry due to the ability of some strains to persist in food-associated environments. Biofilm production is presumed to contribute to increased L. monocytogenes resistance and persistence. The aims of this study were to (1) assess the biofilm formation of L. monocytogenes isolates from a meat processing facility and sheep farm previously characterized and subjected to whole-genome sequencing and (2) perform a comparative genomic analysis to compare the biofilm formation and the presence of a known set of biofilm-associated genes and related resistance or persistence markers. Among the 37 L. monocytogenes isolates of 15 sequence types and four serogroups involved in this study, 14%, 62%, and 24% resulted in the formation of weak, moderate, and strong biofilm, respectively. Increased biofilm-forming ability was associated with the presence of the stress survival islet 1 (SSI-1), inlL, and the truncated inlA genes. Combining the phenotypic and genotypic data may contribute to understanding the relationships between biofilm-associated genes and L. monocytogenes biofilm-forming ability, enabling improvement in the control of this foodborne pathogen. [ABSTRACT FROM AUTHOR]

The terminal restriction fragment length polymorphism munities from different collecting places was evaluated was used to determine the bacterial diversity in rhizo- by principal component analysis. Results showed that sphere of maize (Zea mays L.) collected from four sites the most different bacterial community originated from of experimental field plot in two dates of the vegetation marginal part of the experimental field plot collected in season (July and September). The 16S rRNA gene was September was caused probably by combination of the amplified from metagenomic DNA using universal eubac- marginal effect and drought before sampling date in Sep- terial primers and PCR products were digested separately tember. Other rhizosphere samples showed from moderate with three restriction enzymes. Significant differences in to small differences in the structure of the bacterial com- the number of terminal restriction fragments among rhi- munity. Nevertheless, significant differences among all zosphere samples and between sampling dates were not collected bacterial communities were not observed. detected (P < 0.05). Variation within the bacterial communities from different collecting places was evaluated by principal component analysis. Results showed that the most different bacterial community originated from marginal part of the experimental field plot collected in September was caused probably by combination of the marginal effect and drought before sampling date in September. Other rhizosphere samples showed from moderate to small differences in the structure of the bacterial community. Nevertheless, significant differences among all collected bacterial communities were not observed.

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This work was aimed at determining the occurrence and diversity of Listeria monocytogenes in a traditional meat-processing facility to reveal persistent contamination. A total of 268 samples, including 196 environmental samples and 72 meat samples were collected during a four-year period, and 70 were found to be L. monocytogenes positive. Molecular serotyping of 77 isolates classified these strains into four serogroups, with the majority of 34 strains in serogroup IIa. To reveal the persistent contamination, subtyping by AscI/ApaI-PFGE was applied. Cluster analysis resulted in strain discrimination into 18 profiles. Strains with PFGE/MLST-ST classification as 1/ST9, 2/ST14 and 9/ST2 were predominant and considered persistent. Based on the results of PFGE, a spatial and temporal map of persistent L. monocytogenes contamination was drawn. Subtyping by PFGE was used as a reliable tool to reveal persistent contamination and, complemented with virulence characteristics, can contribute to the improvement of L. monocytogenes control programs in food processing. Practical application Listeria monocytogenes is a food-borne pathogen with significant public health and economic impact. This study, focused on prevalence and tracing of L. monocytogenes strains in a traditional meat-processing facility, revealed persistent contamination by the pathogen. Data of PFGE profiling from repeated samplings over a four-year period facilitated to draw a spatial and temporal map of persistent L. monocytogenes strains spreading in a meat-processing facility and, subsequently, will allow optimisation of cleaning and disinfection measures to ensure hygiene. Based on the detection of virulence factors, persistent ECIII and comK prophage-positive strains were observed, indicating a higher risk of contamination by more virulent L. monocytogenes strains. The obtained results clearly indicate, that most attention should be paid to control strategy improvement in the meat processing chain focused preferably on prevention, not only to final products. [ABSTRACT FROM AUTHOR]

Overall cell surface hydrophobicity (CSH) is predicted to play an important role during biofilm formation in Candida albicans but is the result of many expressed proteins. This study compares the CSH status and CSH1 gene expression in C. albicans planktonic cells, sessile biofilm, and dispersal cells. Greater percentages of hydrophobic cells were found in non-adhered (1.5 h) and dispersal forms (24 or 48 h) (41.34±4.17% and 39.52±7.45%, respectively), compared with overnight planktonic cultures (21.69±3.60%). Results from quantitative real-time PCR confirmed greater up-regulation of the CSH1 gene in sessile biofilm compared with both planktonic culture and dispersal cells. Up-regulation was also greater in dispersal cells compared with planktonic culture. The markedly increased CSH found both in C. albicans biofilm, and in cells released during biofilm formation could provide an advantage to dispersing cells building new biofilm. [ABSTRACT FROM AUTHOR]

Hemp seeds are increasingly produced on small farms in Slovakia and used for production of food. We detected contamination of 1.4 x 107 CFU·g-1 coliform coliform bacteria in hemp seeds from a small farm and isolated three strains of Escherichia coli. These were characterized by GTG-typing and by whole genome sequencing. The three strains were indistinguishable from each other by GTG-typing but different from a reference strain E. coli CCM 2024. They were not distinguished either by multi-locus sequence type (MLST) deduced from whole genome sequences, as all strains were of sequence type 58, or by core genome-based MLST (cgMLST), as all strains belonged to type 148521. All strains were found to be fumC4/fimH32 type and serotype H21, O-antigen was not identified. No plasmid origin was detected. No gene encoding for shiga toxin was detected. Several virulence-associated genes were detected in all three strains at high identities with sequences in the database, namely, fimH, lpfA, terC, csgA, hlyE, nlpI, yehB, yehC and yehD. Further virulence-associated genes were detected at shorter lengths, namely, fdeC, gad and yehA. Several antibiotic resistance genes were also identified. The strains were found to be virtually identical. With a probability of being a human pathogen, they need to be addressed for on-farm food production safety. [ABSTRACT FROM AUTHOR]

Seven variable-number tandem repeat (VNTR) markers, which had previously proven to be suitable for typing of Salmonella enterica serovar Typhimurium or S. enterica serovar Enteritidis, were evaluated for their discrimination power in multilocus VNTR analysis (MLVA) on a panel of 83 S. enterica strains belonging to 23 different serovars, which had been isolated from food and animal samples. Strains varied not only in numbers of tandem repeats, but also in the presence or absence of VNTR alleles. The greatest polymorphism was observed in STTR5, STTR3 and STTR7 loci. Based on combined allelic profiles of all seven VNTR loci, it was possible to distinguish as many as 50 different MLVA profiles. The MLVA clustering of strains parallelled serotyping results to a reasonable extent. In addition, a high degree of intra-serovar variability was observed in strains of serovars Bareilly, Bredeney, Dublin, Enteritidis, Havana, Saintpaul, Senftenberg, Schwarzengrund and Typhimurium. MLVA proved to be more discriminative than dnaN housekeeping gene sequencing. The optimized MLVA method can be advantageously used in tracing of Salmonella contamination of food products. [ABSTRACT FROM AUTHOR]

Lysogenic bacteriophages are a significant source of variability in closely related Salmonella strains. In this study, screening for diversity of 152 Salmonella Typhimurium strains was performed using PCR detection of selected prophage regions derived from phages P22, Gifsy-1, Gifsy-2, Fels-1, ST104 and SopEΦ. A high degree of variability was observed in the presence of specific genes. Based on the presence of particular prophage genes, we divided strains into 37 different PCR-prophage profiles; 20 of them were represented by only a single strain. Using multilocus variable number tandem repeats analysis (MLVA), 152 Salmonella strains were separated into 82 MLVA strings. Similar grouping of Salmonella strains was observed in the case of PCR-prophage detection and MLVA and the results corresponded well with the phage type of strains. However, several Salmonella strains were detected, which were closely related according to MLVA; yet, they differed in PCR phage profiles. The observations support a view that integration/excision of bacteriophages in Salmonella strains are frequent events shaping the bacterial genome. [ABSTRACT FROM AUTHOR]

Microbial contamination of oil seeds can cause their deterioration leading to reduction of the quality of the produced oil. Knowledge of the levels and composition of microbial communities may be therefore helpful to set up the effective control measures. Seeds of hemp and poppy (blue and white cultivars) from two farms in Slovakia were analysed by culture-based microbiological methods and by metagenomic high-throughput sequencing of 16S rDNA and 28S rDNA to provide information on surface bacterial and fungal communities. The results of culture-based analysis showed a comparatively high level of contamination by bacteria and by fungi of hemp seeds. High-throughput sequencing revealed that the bacterial community of hemp seeds consisted mainly of families Enterobacteriaceae and Pseudomonadaceae. The fungal community was composed mainly of Pleosporaceae, Davidiellaceae and Tremellaceae. In poppy seeds, the bacterial community was found to be composed mainly of Enterobacteriaceae (genus Klebsiella), Pseudomonadaceae and Xanthomonadaceae or Streptomycetaceae. The fungal community was composed mainly of Pleosporaceae and Davidiellaceae (genus Cladosporium), while some samples were characterized by increased levels of Trichocomaceae (genus Aspergillus). The determined presence of pseudomonads and aspergilli in certain seeds may indicate that more effective cleaning and sanitation will be required as they could affect the produced oil. [ABSTRACT FROM AUTHOR]

Euglena gracilis is a fresh-water flagellate possessing secondary chloroplasts of green algal origin. In contrast with organisms possessing primary plastids, mRNA levels of nucleus-encoded genes for chloroplast proteins in E. gracilis depend on neither light nor plastid function. However, it remains unknown, if all these mRNAs are trans-spliced and possess spliced leader sequence at the 5′-end and if trans-splicing depends on light or functional plastids. This study revealed that polyadenylated mRNAs encoding the chloroplast proteins glyceraldehyde-3-phosphate dehydrogenase ( GapA), cytochrome f ( PetA), and subunit O of photosystem II ( PsbO) are trans-spliced irrespective of light or plastid function. [ABSTRACT FROM AUTHOR]