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In this study, we decided to test the hypothesis that the fungal biostarter M. flavus used during a 21-day beef dry-aging process significantly impacts the composition of other microorganisms, the profile of volatile compounds, meat hardness characteristics, and, consequently, the sensory quality. The experiments were performed on samples derived from animals crossbred between Holstein–Fresian cows and meat breed bulls. Two groups of samples were studied, including the control group, without biostarter, and a group inoculated with the M. flavus biostarter. Both sample groups were seasoned for 21 days in the dry-aging fridge. The physicochemical parameters (pH, color parameters), the chemical composition of muscle, the determination of the shear force, the profile of volatile compounds (VOCs), and the sensory quality were evaluated after aging. During this study, classical microbiological methods were used to investigate the influence of fungal biostarters on the growth and survival of bacteria and other fungi (e.g., yeasts) during the dry-aging process of beef (DAB). The M. flavus biostarter improved the sensory quality of DAB, allowing high sensory quality to be achieved after just 21 days. This is likely due to the diverse VOCs produced by the fungus, including 1-tetradecanol, 2-nonenal, trans-2-undecenoic acid, and the following esters: formic acid hexyl ester, 10-undecenoic acid methyl ester, and 4-methylpentanoic acid methyl ester. The presence of the biostarter had no significant effect on the number of the bacteria or the survivability of the L. monocytogenes on the meat's surface in laboratory conditions. [ABSTRACT FROM AUTHOR]

Bacillus cereus is a foodborne pathogen causing food safety issues due to the formation of difficult to eliminate spores and biofilms. The objective of this study was to investigate the occurrence of B. cereus (conducted as part of monitoring in 2017-2018) and the presence of a toxin gene in strains isolated from retail products (pastries/cakes; vegetables, spices, delicatessen products) in Poland, and to determine the susceptibility of these microorganisms to different antimicrobial agents. A total of 267 B. cereus isolates from food products were examined, of which 95.51% were found positive for the presence of at least one toxin gene, with the highest frequency of the nhe gene (91.39%). The hbl and cytK genes were detected in 53.56% and 44.19% of B. cereus strains, respectively. The lowest frequency was found for the ces gene (2.62%). The susceptibility of B. cereus isolates to 16 antimicrobials was investigated. Ampicillin and penicillin resistance was the most common resistance phenotype and was identified in 100% of the B. cereus isolates. In addition, the tested isolates exhibited resistance to: amoxicillin-clavulanic acid (96.25%), cephalothin (67.79%), ceftriaxone (64.42%), rifampicin (46.82%), trimethoprim-sulfamethoxazole (5.62%), quinupristin/dalfopristin (4.87%), chloramphenicol (3.75%), clindamycin (2.62%), teicoplanin (1.87%), erythromycin (1.87%), ciprofloxacin (0.75%), imipenem (0.75%), tetracycline (0.37%), and gentamicin (0.37%). The study results contribute to characterizing the diversity of B. cereus isolated from various food products in Poland and their impact on food safety and public health. This study delivers practical information on antibiotic resistance and the frequency of toxin genes among strains isolated from food. [ABSTRACT FROM AUTHOR]

The B-cell CLL/lymphoma 11B gene (BCL11B) plays a crucial role in T-cell development, but its role in T-cell malignancies is still unclear. To study its role in the development of T-cell neoplasms, we generated an inducible BCL11B knockout in a murine T cell leukemia/lymphoma model. Mice, bearing human oncogenes TAL BHLH Transcription Factor 1 (TAL1; SCL) or LIM Domain Only 1 (LMO1), responsible for T-cell acute lymphoblastic leukemia (T-ALL) development, were crossed with BCL11B floxed and with CRE-ER/lox mice. The mice with a single oncogene BCL11Bflox/floxCREtg/tgTAL1tg or BCL11Bflox/floxCREtg/tgLMO1tg were healthy, bred normally, and were used to maintain the mice in culture. When crossed with each other, >90% of the double transgenic mice BCL11Bflox/floxCREtg/tgTAL1tgLMO1tg, within 3 to 6 months after birth, spontaneously developed T-cell leukemia/lymphoma. Upon administration of synthetic estrogen (tamoxifen), which binds to the estrogen receptor and activates the Cre recombinase, the BCL11B gene was knocked out by excision of its fourth exon from the genome. The mouse model of inducible BCL11B knockout we generated can be used to study the role of this gene in cancer development and the potential therapeutic effect of BCL11B inhibition in T-cell leukemia and lymphoma. [ABSTRACT FROM AUTHOR]

T cell lymphomas (TCL) comprise a heterogeneous group of non-Hodgkin lymphomas (NHL) that often present at an advanced stage at the time of diagnosis and that most commonly have an aggressive clinical course. Treatment in the front-line setting is most often cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or CHOP-like regimens, which are effective in B cell lymphomas, but in TCL are associated with a high failure rate and frequent relapses. Furthermore, in contrast to B cell NHL, in which substantial clinical progress has been made with the introduction of monoclonal antibodies, no comparable advances have been seen in TCL. To change this situation and improve the prognosis in TCL, new gene-targeted therapies must be developed. This is now possible due to enormous progress that has been made in the last years in the understanding of the biology and molecular pathogenesis of TCL, which enables the implementation of the research findings in clinical practice. In this review, we present new therapies and current clinical and preclinical trials on targeted treatments for TCL using histone deacetylase inhibitors (HDACi), antibodies, chimeric antigen receptor T cells (CARTs), phosphatidylinositol 3-kinase inhibitors (PI3Ki), anaplastic lymphoma kinase inhibitors (ALKi), and antibiotics, used alone or in combinations. The recent clinical success of ALKi and conjugated anti-CD30 antibody (brentuximab-vedotin) suggests that novel therapies for TCL can significantly improve outcomes when properly targeted. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a potential hazard for food safety and therefore for public health. The aim of the present study was to determine the prevalence and characteristics of L. monocytogenes in Polish ready-to-eat (RTE) meat products for retail sale. Among the 184,439 food samples collected within the framework of a national official control and monitoring program, only 0.3% were positive for L. monocytogenes. A significant group of products that did not meet the criteria were RTE meat products. This group accounted for 40% of all noncompliant samples. Seventy L. monocytogenes isolates from these RTE meat products (meat, sausages, and delicatessen products with meat) were examined. The majority of the tested isolates (51%) belonged to serogroup 1/2a-3a followed by 1/2c-3c (21%), 1/2b-3b-7 (14%), and 4ab-4b-4d-4e (13%). Serogroup 4a-4c was not present among the tested isolates. All L. monocytogenes isolates harbored the virulence-associated genes inlA, inlC, inlJ, and lmo2672. The llsX marker was detected in 12 (17%) of the 70 isolates. Ampicillin resistance was the most common resistance phenotype and was identified in 83% of the L. monocytogenes isolates. A low incidence of resistance to amoxicillin-clavulanic acid (6% of isolates) was also detected. All L. monocytogenes isolates were susceptible to chloramphenicol, gentamicin, ciprofloxacin, meropenem, sulfamethoxazole-trimethoprim, tetracycline, and erythromycin. This work provides useful information regarding contamination of RTE meat products with L. monocytogenes, which may have implications for food safety risks. [ABSTRACT FROM AUTHOR]

According to EU summary report on zoonoses, zoonotic agents and food‐borne outbreaks in 2017, Campylobacter was the most commonly reported gastrointestinal bacterial pathogen in humans in the EU. Unfortunately, the standard methods for the detection of thermotolerant Campylobacter spp. in foods are time‐consuming. Additionally, the qualified staff is obligatory. For this reason, new methods of pathogens detection are needed. The present work demonstrates that surface‐enhanced Raman scattering (SERS) is a reliable and fast method for detection of Campylobacter spp. in food samples. The proposed method combines the SERS measurements performed on an Ag/Si substrate with two initial steps of the ISO standard procedure. Finally, the principal component analysis (PCA) allows for statistical classification of the studied bacteria. By applying the proposed ISO‐SERS‐PCA method in the case of Campylobacter bacteria the total detection time may be reduced from 7 to 8 days required by ISO method to 3 to 4 days in the case of SERS‐based approach. [ABSTRACT FROM AUTHOR]

The surface-enhanced Raman spectroscopy (SERS)-based analysis of bacteria suffers from the lack of a standard SERS detection protocol (type of substrates, excitation frequencies, and sampling methodologies) that could be employed throughout laboratories to produce repeatable and valuable spectral information. In this work, we have examined several factors influencing the spectrum and signal enhancement during SERS studies conducted on both Gram-negative and Gram-positive bacterial species: Escherichia coli and Bacillus subtilis, respectively. These factors can be grouped into those which are related to the structure and types of plasmonic systems used during SERS measurements and those that are associated with the culturing conditions, types of culture media, and method of biological sample preparation. [ABSTRACT FROM AUTHOR]

One of the potential applications of surface-enhanced Raman spectroscopy (SERS) is the detection of biological compounds and microorganisms. Here we demonstrate that SERS coupled with principal component analysis (PCA) serves as a perfect method for determining the taxonomic affiliation of bacteria at the strain level. We demonstrate for the first time that it is possible to distinguish different genoserogroups within a single species, Listeria monocytogenes, which is one of the most virulent foodborne pathogens and in some cases contact with which may be fatal. We also postulate that it is possible to detect additional proteins in the L. monocytogenes cell envelope, which provide resistance to benzalkonium chloride and cadmium. A better understanding of this infectious agent could help in selecting the appropriate pharmaceutical product for enhanced treatment.ᅟ [ABSTRACT FROM AUTHOR]

We show that surface-enhanced Raman spectroscopy (SERS) coupled with principal component analysis (PCA) can serve as a fast, reliable, and easy method for detection and identification of food-borne bacteria, namely Salmonella spp., Listeria monocytogenes, and Cronobacter spp., in different types of food matrices (salmon, eggs, powdered infant formula milk, mixed herbs, respectively). The main aim of this work was to introduce the SERS technique into three ISO (6579:2002; 11290-1:1996/A1:2004; 22964:2006) standard procedures required for detection of these bacteria in food. Our study demonstrates that the SERS technique is effective in distinguishing very closely related bacteria within a genus grown on solid and liquid media. The advantages of the proposed ISO-SERS method for bacteria identification include simplicity and reduced time of analysis, from almost 144 h required by standard methods to 48 h for the SERS-based approach. Additionally, PCA allows one to perform statistical classification of studied bacteria and to identify the spectrum of an unknown sample. Calculated first and second principal components (PC-1, PC-2) account for 96, 98, and 90% of total variance in the spectra and enable one to identify the Salmonella spp., L. monocytogenes, and Cronobacter spp., respectively. Moreover, the presented study demonstrates the excellent possibility for simultaneous detection of analyzed food-borne bacteria in one sample test (98% of PC-1 and PC-2) with a goal of splitting the data set into three separated clusters corresponding to the three studied bacteria species. The studies described in this paper suggest that SERS represents an alternative to standard microorganism diagnostic procedures. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to determine the prevalence of thermophilic Campylobacter in poultry, pork, and beef meat at the retail level and to identify the main categories of meat representing the most significant reservoirs of Campylobacter. A monitoring study was conducted throughout Poland from 2009 to 2013. A total of 1,700 fresh meat samples were collected from supermarkets, large retail outlets, and smaller stores. Thermophilic Campylobacter species were detected in 690 (49.3%) of 1,400 poultry samples collected from retail trade. Strains were isolated from 50.2 and 41.1% of raw chicken and turkey meat samples, respectively, and from 50.1 and 42.6% of raw chicken and turkey giblets. The incidence of Campylobacter spp. on pork ( 10.6%) and beef ( 10.1 %) was significantly lower than on poultry. Campylobacter jejuni was the most prevalent Campylobacter species in chicken (46.6%), pork (68.6%), and beef (66.7%), and Campylobacter coli was the most frequently isolated Campylobacter species in turkey meat (71.2%). This study revealed that retail raw meats are often contaminated with Campylobacter; however, the prevalence of these pathogens is markedly different in different meats. Raw retail meats are potential vehicles for transmitting foodborne diseases, and our findings stress the need for increased implementation of hazard analysis critical control point programs and consumer food safety education efforts. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a Gram-positive bacterium causing rare but dangerous cases of disease in humans and animals. The β-lactams penicillin G and ampicillin are the antibiotics of choice in the treatment of listeriosis. Recently, lmo1941, encoding a surface protein of L. monocytogenes with unknown function, was identified as a gene transcriptionally upregulated under penicillin G pressure. In this study, the effect of lmo1941 knockout on the susceptibility of L. monocytogenes to β-lactams was examined. Deletion mutant in lmo1941 was constructed and subjected to studies, which revealed that the deletion of lmo1941 had no effect on susceptibility and tolerance to penicillin G and ampicillin but resulted, however, in increased susceptibility of L. monocytogenes to several cephalosporins. Subsequently, the potential effect of lmo1941 mutation on the cell wall of L. monocytogenes was investigated. The analysis revealed quantitative changes in the muropeptide profile of peptidoglycan and a decrease in density of the high-density zone of cell wall of the mutant strain. Both these changes were observed in cells taken from the stationary phase. These results indicate that the surface protein Lmo1941 affects peptidoglycan composition and cell wall structure of L. monocytogenes in the stationary phase of growth. [ABSTRACT FROM AUTHOR]

In 2007 and 2008, a monitoring study was carried out in Poland to examine the occurrence of thermotolerant Campylobacter spp. in raw and cooked chicken products available on the retail market. A total of 912 samples were tested: 443 samples of raw chicken meat, 146 samples of giblets, and 323 ready-to-eat poultry products (150 samples of spit-roasted chicken, 56 samples of smoked chicken, and 117 samples of pâté and cold meats). A high level of contamination of raw chicken meat (51.7% o samples) and chicken giblets (47.3% of samples) was detected. However, thermotolerant Campylobacter spp. were found in only 1.2% of the ready-to-eat poultry products. [ABSTRACT FROM AUTHOR]

Background: Bacterial penicillin-binding proteins (PBPs) can be visualized by their ability to bind radiolabeled or fluorescent β-lactam derivatives both whole cells and membrane/cell enriched fractions. Analysis of the Listeria monocytogenes genome sequence predicted ten genes coding for putative PBPs, but not all of their products have been detected in studies using radiolabeled antibiotics, thus hindering their characterization. Here we report the positive identification of the full set of L. monocytogenes PBPs and the characteristics of the hitherto undescribed PBPD2 (Lmo2812). Results: Eight L. monocytogenes PBPs were identified by the binding of fluorescent β-lactam antibiotic derivatives Boc-FL, Boc-650 and Amp-Alexa430 to proteins in whole cells or membrane/cell wall extracts. The gene encoding a ninth PBP (Lmo2812) was cloned and expressed in Escherichia coli as a His-tagged protein. The affinity purified recombinant protein had DD-carboxypeptidase activity and preferentially degraded low-molecular-weight substrates. L. monocytogenes mutants lacking the functional Lmo2812 enzyme were constructed and, compared to the wild-type, the cells were longer and slightly curved with bent ends. Protein Lmo1855, previously designated PBPD3, did not bind any of the antibiotic derivatives tested, similarly to the homologous enterococcal protein VanY. Conclusions: Nine out of the ten putative L. monocytogenes PBP genes were shown to encode proteins that bind derivatives of β-lactam antibiotics, thus enabling their positive identification. PBPD2 (Lmo2812) was not visualized in whole cell extracts, most probably due to its low abundance, but it was shown to bind Boc-FL after recombinant overexpression and purification. Mutants lacking Lmo2812 and another low molecular mass (LMM) PBP, PBP5 (PBPD1) - both with DD-carboxypeptidase activity - displayed only slight morphological alterations, demonstrating that they are dispensable for cell survival and probably participate in the latter stages of peptidoglycan synthesis. Since Lmo2812 preferentially degrades low-molecular- mass substrates, this may indicate a role in cell wall turnover. [ABSTRACT FROM AUTHOR]

Campylobacter-associated gastroenteritis remains an important cause of morbidity worldwide, and some evidence suggests that poultry is an important source of this foodborne infection in humans. This study was conducted to analyze the prevalence and genetic background of resistance of 149 Campylobacterjejuni and 54 Campylobacter coli strains isolated from broiler chicken carcasses and from stool samples of infected children in Poland from 2003 through 2005. Nearly all isolates were susceptible to macrolides and aminoglycosides. The highest resistance in both human and chicken strains was observed for ciprofloxacin (more than 40%), followed by ampicillin (13 to 21%), and tetracycline (8 to 29%). Resistance to ampicillin and tetracycline rose significantly between 2003 and 2005. Slight differences in resistance between human and chicken isolates indicate that although chicken meat is not the only source of Campylobacter infection in our population, it can be involved in the transmission of drug-resistant Campylobacter strains to humans. [ABSTRACT FROM AUTHOR]

Abstract: We report on the cloning of the structural gene for penicillin-binding protein 5 (PBP5), lmo2754. We also describe the enzymatic activity of PBP5 and characterize a mutant lacking this activity. Purified PBP5 has dd-carboxypeptidase activity, removing the terminal d-alanine residue from murein pentapeptide side chains. It shows higher activity against low molecular weight monomeric pentapeptide substrates compared to dimeric pentapeptide compound. Similarly, PBP5 preferentially cleaves monomeric pentapeptides present in high-molecular weight murein sacculi. A Listeria monocytogenes mutant lacking functional PBP5 was constructed. Cells of the mutant are viable, showing that the protein is dispensable for growth, but grow slower and have thickened cell walls. [Copyright &y& Elsevier]

Bacteria of the genus Listeria (phylum Firmicutes) include both human and animal pathogens, as well as saprophytic strains. A common component of Listeria spp. genomes are plasmids, i.e., extrachromosomal replicons that contribute to gene flux in bacteria. This study provides an in-depth insight into the structure, diversity and evolution of plasmids occurring in Listeria strains inhabiting various environments under different anthropogenic pressures. Apart from the components of the conserved plasmid backbone (providing replication, stable maintenance and conjugational transfer functions), these replicons contain numerous adaptive genes possibly involved in: (i) resistance to antibiotics, heavy metals, metalloids and sanitizers, and (ii) responses to heat, oxidative, acid and high salinity stressors. Their genomes are also enriched by numerous transposable elements, which have influenced the plasmid architecture. The plasmidome of Listeria is dominated by a group of related replicons encoding the RepA replication initiation protein. Detailed comparative analyses provide valuable data on the level of conservation of these replicons and their role in shaping the structure of the Listeria pangenome, as well as their relationship to plasmids of other genera of Firmicutes, which demonstrates the range and direction of flow of genetic information in this important group of bacteria. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a pathogen responsible for severe cases of food poisoning. Listeria spp. strains occurring in soil and water environments may serve as a reservoir of resistance determinants for pathogenic L. monocytogenes strains. A large collection of Listeria spp. strains (155) isolated from natural, agricultural, and urban areas was screened for resistance to heavy metals and metalloids, and the presence of resistance determinants and extrachromosomal replicons. Of the tested strains, 35% were resistant to cadmium and 17% to arsenic. Sequence analysis of resistance plasmids isolated from strains of Listeria seeligeri and Listeria ivanovii, and the chromosome of L. seeligeri strain Sr73, identified a novel variant of the cadAC cadmium resistance efflux system, cadA6, that was functional in L. monocytogenes cells. The cadA6 cassette was detected in four Listeria species, including strains of L. monocytogenes, isolated from various countries and sources—environmental, food-associated, and clinical samples. This resistance cassette is harbored by four novel composite or non-composite transposons, which increases its potential for horizontal transmission. Since some cadAC cassettes may influence virulence and biofilm formation, it is important to monitor their presence in Listeria spp. strains inhabiting different environments. [ABSTRACT FROM AUTHOR]

The authors would like to call the reader's attention to the fact that unfortunately following information was missing in the original article: "Evelin Witkowska is supported by the Foundation of Polish Science (FNP)." [ABSTRACT FROM AUTHOR]