As an important source of human food, milk can be a carrier of human pathogenic bacteria, including tuberculous and nontuberculous mycobacteria (NTM), in its raw and unpasteurized state. In this research, 175 raw milk samples and 175 traditional cheese samples were collected from traditional dairy stores in 22 regions of Tehran in a 9- month period from August 2019 to May 2020. Samples were prepared and transferred to a specialized laboratory, where they were inoculated in Lowenstein-Jensen (LJ) medium containing glycerol or sodium pyruvate, as well as Herrold's egg-yolk with and without Mycobactin J. to determine the sample's identity of samples. The recommended 16S rRNA (1436 bp) and hsp65 (644 bp) gene fragments from the positive isolates identified in Ziehl-Neelsen (Z-N) staining were amplified and sequenced using PCR and compared with the sequences of the gene fragments of reference strains available in the global GenBank database. No mycobacterial species were isolated from traditional cheese samples in microbial culture. In case of raw milk samples, a total of four bacteria were collected, all of which were found in the genetic differential testing to be NTM, including n = 1 Mycobacterium heraklionense, n = 2 Mycolicibacterium fortuitum, and n = 1 Mycobacterium thermoresistibile. The analysis of the results obtained by isolate sequencing using the 16S rRNA gene showed higher discriminatory power and percentage similarities in the identification of the isolates than the hsp65 gene.
- MeSH
- atypické mykobakteriální infekce * mikrobiologie MeSH
- lidé MeSH
- mléko mikrobiologie MeSH
- netuberkulózní mykobakterie genetika MeSH
- RNA ribozomální 16S genetika MeSH
- sýr * mikrobiologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Írán MeSH
This study was conducted to determine the effect of 1-stage homogenization (OSH) and 2-stage homogenization (TSH) and the addition of polysaccharides [κ-carrageenan (CR) or furcellaran (FR) at levels ranging from 0.000 to 1.000% (wt/wt)] on the physicochemical, viscoelastic, and mechanical vibration damping properties of processed cheese sauces (PCS) after 30 d of storage (6 ± 2°C). The basic chemical properties (pH, dry matter content) were similar for all tested samples. Viscoelastic measurements indicated that PCS rigidity was directly proportional to increasing CR or FR concentration and to the application of homogenization. The interactions between the application of homogenization and the concentration of polysaccharides used were also significant. Compared with OSH, TSH did not lead to any further increase in the rigidity. The preceding results were also supported by data obtained from a nondestructive method of mechanical vibration damping. No changes in water activity were observed in any PCS sample. Overall, the addition of FR or CR appeared to be highly suitable for increasing the emulsion stability of PCS. If PCS products with softer consistency are desired, then a concentration of CR/FR ≤0.250% (wt/wt) could be recommended together with OSH/TSH. For products for which a firmer PCS consistency is required, the addition of CR in concentrations of ≥0.500% (wt/wt) or FR in concentrations of ≥1.000% (wt/wt) together with OSH is recommended. Finally, as the concentration of polysaccharides increased, a darker PCS color was observed.
- MeSH
- karagenan MeSH
- manipulace s potravinami metody MeSH
- polysacharidy MeSH
- reologie MeSH
- sýr * analýza MeSH
- thyreotropin MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Tyramine is one of the most toxic biogenic amines and it is produced commonly by lactic acid bacteria in fermented food products. In present study, we investigated the influence of selected nisin-producing Lactococcus lactis subsp. lactis strains and their cell-free supernatants (CFSs) on tyramine production by four Lactobacillus and two Lactiplantibacillus strains isolated from cheese and beer. Firstly, we examined the antimicrobial effect of the CFSs from twelve Lactococcus strains against tested tyramine producers by agar-well diffusion assay. Six Lactococcus strains whose CFSs showed the highest antimicrobial effect on tyramine producers were further studied. Secondly, we investigated the influence of the selected six Lactococcus strains and their respective CFSs on tyramine production by tested Lactobacillus and Lactiplantibacillus strains in MRS broth supplemented with 2 g.L-1 of l-tyrosine. Tyramine production was monitored by HPLC-UV. The tyramine formation of all tested Lactobacillus and Lactiplantibacillus strains was not detected in the presence of Lc. lactis subsp. lactis CCDM 71 and CCDM 702, and their CFSs. Moreover, the remainder of the investigated Lactococcus strains (CCDM 670, CCDM 686, CCDM 689 and CCDM 731) and their CFSs decreased tyramine production significantly (P < 0.05) - even suppressing it completely in some cases - in four of the six tested tyramine producing strains.
- MeSH
- antibakteriální látky analýza metabolismus farmakologie MeSH
- kultivační média chemie metabolismus farmakologie MeSH
- Lactobacillaceae účinky léků růst a vývoj izolace a purifikace MeSH
- Lactobacillus účinky léků růst a vývoj izolace a purifikace MeSH
- Lactococcus lactis chemie metabolismus MeSH
- pivo mikrobiologie MeSH
- sýr mikrobiologie MeSH
- tyramin analýza metabolismus farmakologie MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Publikační typ
- časopisecké články MeSH
From 98 Lactobacillus strains, isolated from Algerian homemade cheeses, 14 (B1-B14) were selected based on their anti-Escherichia coli and anti-Staphylococcus aureus activities. These strains were also tested towards Listeria monocytogenes 161 and Salmonella Typhimurium LT2 and further investigated for their resistance to simulated gastrointestinal digestion, cell surface properties, ability to adhere to HT-29 cells, cholesterol lowering, antioxidant activity, and technological traits. Five isolates (B9, B13, B18, B19, and B38) were active against L. monocytogenes and Salmonella. From them, three isolates, identified as Lactobacillus brevis (B9, B13, and B38) by MALDI-TOF spectrometry and 16S rDNA sequencing, exhibited high tolerance to pancreatic juice, bile salts and acidic juices, high percentages of hydrophobicity (87, 92, and 81%, respectively), auto-aggregation (61, 68, and 72%, respectively), and adherence to HT-29 cells (79, 84, and 74%, respectively), which testify on their potential of colonization of the human intestine. On the other way, the strains B9 and B13 manifested the most relevant antioxidant activity and cholesterol-lowering ability, respectively. L. brevis strains showed low acidifying and good proteolytic activities with noticeable heat tolerance. The results gathered in this study highlighted the richness of Algerian artisanal cheeses on new lactobacilli strains with an excellent probiotic potential and demonstrated that L. brevis, largely used as nonstarter in cheese manufacture, could be exploited also as a probiotic for human use.
- MeSH
- antibióza MeSH
- bakteriální adheze MeSH
- buňky HT-29 MeSH
- Escherichia coli fyziologie MeSH
- Levilactobacillus brevis * izolace a purifikace fyziologie MeSH
- lidé MeSH
- Listeria monocytogenes * fyziologie MeSH
- potravinářská mikrobiologie * MeSH
- probiotika * izolace a purifikace metabolismus MeSH
- RNA ribozomální 16S genetika MeSH
- Staphylococcus aureus fyziologie MeSH
- sýr * mikrobiologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The aim of this study was to determine prevalence of undesirable bacteria and their antimicrobial profile in samples obtained from a productive farm situated in border region Slanské vrchy (Slovakia), involved in keeping sheep and goats for the purpose of processing raw milk to special products (cheeses). Genus and species identification was carried out by PCR method and MALDI -TOF MS. Isolates thus identified were detected for antimicrobial resistance using the Agar Dilution Method. Bacteria of Staphylococcus spp. exhibited the highest resistance to penicillin (98% isolates). Isolates from the family Enterobacteriacae showed the highest resistance to azithromycin (90%). At the same time, in isolates of Enterococcus spp. we detected high resistance to linezolid (100%). Our investigation showed that all tested strains were resistant to more than one antibiotic used in this study.
- MeSH
- antibakteriální látky farmakologie MeSH
- Bacteria účinky léků MeSH
- bakteriální léková rezistence MeSH
- kozy mikrobiologie MeSH
- ovce mikrobiologie MeSH
- sýr mikrobiologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Slovenská republika MeSH
OBJECTIVE: Desalination of cheese whey by electrodialysis yields saline wastewater (SWW). The goal was to test this as the basis of a culture medium and to prove experimentally the concept that it was a suitable resource for heterotrophic cultivation of the freshwater green microalga Chlorella vulgaris. RESULTS: Optimization of glucose concentration, nitrogen source and medium salinity for microalgal growth was first carried out in defined medium (DM) and shake flasks. These results were then adopted in shake flask cultivation experiments using pre-treated SWW medium (PSWW). Subsequently, microalgal growth under optimized conditions was tested in bioreactors. Various media such as DM, PSWW and diluted PSWW (DPSWW) were compared. Volumetric biomass productivities decreased in the order DM (0.371 g L-1 h-1, urea) > DPSWW (0.315 g L-1 h-1, soy peptone) > PSWW (0.152 g L-1 h-1, soy peptone). Although biomass productivities in DPSWW and PSWW media were significantly lower than in DM, these media required the addition of only 66 and 33% of DM N sources, respectively. No other added DM component was necessary in (D)PSWW to achieve microalgal growth. CONCLUSIONS: Although the optimized cultivation of freshwater microalgae on alternative medium based on SWW resulted in biomass productivities lower than those on DM, the required addition of N sources was also lower. Potentially lower production costs of Chlorella biomass and the meaningful use of SWW are the main outcomes of this work.
Oštiepok is traditional half-fat semi-hard cheese manufactured in Slovak Republic. In this research, we have analyzed the content of macro-elements (calcium, potassium, magnesium, and sodium) and micro-elements (chromium, copper, iron, manganese, molybdenum, selenium, and zinc) in Oštiepok cheese samples collected from various parts of Slovak Republic. The analysis of Oštiepok cheese samples (n = 19) was carried out by using inductively coupled plasma optical emission spectroscopy (ICP-OES). The macro-element concentrations in the investigated samples varied quite significantly with the highest values recorded for sodium with its average concentration of 8083 mg kg-1. The second highest macro-element concentration was observed for calcium with the average concentration of 6850 mg kg-1. Average concentration of zinc was 23.2 mg kg-1; iron, 14.1 mg kg-1; and copper, 10.0 mg kg-1. The concentration of macro- and micro-elements varied from sample to sample, but we can conclude that the traditional Oštiepok cheese is a suitable source of some minerals important for human health. Based on the RDA, the exposure amounts of analyzed samples are low, and no element can be referred to as significant since none reaches 15% of the nutrient reference values, according to EC Regulation 1169/2011.
In Slovakia, dairy products made from ewes' milk have a long tradition. These products include the lactic acid product called "žinčica" which is a by-product occurring during the preparation of ewes' lump cheese. There is no information in the literature regarding the special properties of the microbiota, especially lactic acid Firmicutes, which can survive in "žinčica." From the safety aspect, enterococci are a controversial group of bacteria, and those from "žinčica" have never been tested for their properties. The "žinčica" used in our study was supplied by several different agrofarms producing ewes' lump cheese in central Slovakia. The species Enterococcus faecium (strains EF30E1, EF32E1, EF34E1, EF34E5) and Enterococcus faecalis (strains EE30E4, EE35E1, E31E2, altogether 7) were detected in samples from "žinčica" identified using MALDI-TOF spectrometry with secure genus identification/probable species identification and then confirmed by means of PCR. Enterococci were hemolysis-negative and the genes of the typical enterococcal virulence factors were mostly absent; the gelE gene was found in two E. faecium strains (EF30E1 and EF32E1), the agg gene was detected in E. faecalis EE35E1, and the esp gene was found in two E. faecalis strains (EE30E4 and EE31E2). No strains harbored the cytolysin A gene. Biofilm formation was detected in four strains (EF30E1, EF32E1, EF34E1, and EF34E5), indicating highly positive and low-grade positive biofilm formation. Enterococci were mostly susceptible to antibiotics tested for their phenotype. This is the first study to analyze enterococci in "žinčica."
- MeSH
- antibakteriální látky farmakologie MeSH
- bakteriální proteiny genetika MeSH
- bezpečnost potravin * MeSH
- biofilmy růst a vývoj MeSH
- Enterococcus faecalis účinky léků genetika MeSH
- Enterococcus faecium účinky léků genetika MeSH
- Enterococcus klasifikace účinky léků patogenita MeSH
- faktory virulence genetika MeSH
- mikrobiální testy citlivosti MeSH
- mikrobiota MeSH
- ovce MeSH
- potravinářská mikrobiologie * MeSH
- sýr mikrobiologie MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Slovenská republika MeSH
- MeSH
- aminokyseliny MeSH
- analýza potravin MeSH
- Lactobacillus helveticus MeSH
- potravinářský průmysl metody MeSH
- potraviny MeSH
- sýr * MeSH
- Publikační typ
- přehledy MeSH
