Enterococci and their ability live out activity of sanitation detergents

We evaluated the effect of temperature decrease of sanitation solutions (35 °C) in condition of organic load (1% reconstituted powdered milk) and varying hardness of the water used for solution preparation (0 °, 15 °, 30 ° and 45 °) on the ability to randomly selected strains of enterococci survive exposure to acidic and alkaline sanitation solution (0.5% concentration, contact time 15 minutes) in model experiments. Increasing water hardness also increases the number surviving enterococci. Presence of organic loads and lower temperatures decreased the sanitation effect of the test solutions. The tested strains showed different tolerances to applied sanitation solutions. We found a weaker powerful of acid sanitation solution on base phosphoric acid after its application.https://doi.org/ 10.5219/16

Selected properties of lactic acid bacteria isolated from raw cow's milk

For the identification of lactic acid bacteria derived from raw cow's milk, 151 colonies were isolated. The grow conditions of lactic acid bacteria were at temperature 37 °C for 3 days on MRS medium. Based on microscopical preparation, negative catalase and Gram-positive test were 81 isolates confirmed as genus Lactobacillus. Out of these, 9 isolates were evaluated for acidifying activity in UHT milk at 25 °C, 30 °C and 37 °C at regular intervals during 24 hours. The average count of NSLAB lactobacilli in raw cow's milk reached the value 1.54.104 KTJ.ml-1. It was found that all tested strains of lactobacilli did not cause significant changes of titratable acidity in milk at 25 °C and 30 °C. Only one strain significantly improved the titratable acidity of milk at 37 °C after 24 hours. The acidity reached the value from 7.5 °SH to 41.9 °SH. This strain was confirmed by PCR method as Lactobacillus helveticus

Presence of enterococci in cow milk and their antibiotic resistance

Enterococci represent an important part of contaminate microflora in raw milk and dairy products. They constitute significant part of nosocomial pathogens with a remarkable capacity of expressing resistance to several antimicrobial  agents. We aimed to assess occurrence and antibiotic resistance of enterococci in the raw milk samples and pasteurized milk samples. In this study total bacterial count, psychrotrophic count and count of enterococci were determine in raw milk cistern samples, storage tank milk samples and milk samples after pasteurization. A collection of 46 enterococcal isolates were identified and screened for their antibiotic resistance. Isolates of E. faecalis were dominant in raw milk samples (56.5 %). Sensitive to teicoplanine (30 mcg/disk) were 97.9 % of enterococcal isolates and 15.2 % isolates were resistant to vankomycin (30 mcg/disk)

The quality of processed cheeses and cheese analogues the same brand domestic and foreign production

Processed cheeses belong to Slovakia favorite dairy products. Processed cheeses are made from natural cheeses. In recent years the trend is to replace natural cheeses with other raw materials of non-dairy nature. The composition of the processed cheese analogues is not in many countries defined by legislation. The objective of this study was to determine and compare chemical properties (fat, dry matter, fat in dry matter, NaCl) two samples of processed cheeses (C, D - Veselá krava) and two samples cheese analogues (A, B - Kiri) the same brand domestic and foreign production. The evaluated was taste of processed cheeses and cheese analogues, too. Chemical analysis and sensory analysis were repeated four times. The results of chemical analysis shows that all rated samples processed cheeses made on Slovakia fulfilled demands declared (dry matter and fat in dry matter) as producers provided on the label. The most commonly fluctuate content of NaCl from 1 to 1.24 g.100g-1. The higher coefficient of variation in the determination of NaCl (3.88%) was found in processed cheeses made in France. Processed cheese and cheese analogues made in France had not specified parameters for dry matter and fat in dry matter on the label. For production cheese analogues Kiri made in Slovakia was used different raw material than Kiri made in France. The taste of products was determined by descriptors - salty, slightly sweet, milky, buttery-creamy, fatty, sour, bitter, and unknown. The interesting that Kiri made in Slovakia had stronger milky and buttery-creamy taste than cheese analogue Kiri made in France. Significant differences were found in the slighty sweet taste of processed cheeses, the most points won processed cheese Veselá krava made in Slovakia

Species identification of enterococci by biochemical test and molecular-genetic methods

The aim of this study was comparison different methods of species identification of enterococci. One hundred and fifty three suspected colonies were isolated from milk and dairy products (cheeses from cow´s, ewe´s and goat´s milk). On the bases of their growth on BEA agar, microscopic characteristic, results of Gram staining, catalase test and PYRAtest was thirty four isolates assigned to the genus Enterococcus. These isolates were identified by commercial biochemical test EN-COCCUS. 52.9% of them were included in species E. faecalis, 29.4% in E. faecium, 14.7% in E. durans and 2.9% in E. group III. This group includes 3 species: E. durans, E. hirae, E. faecalis asaccharolytic var. Then 16S rRNA sequencing nucleotide of all isolates was realized. Results of sequencing were compared with NCBI database. Only 14.7% of isolates were in 100% accordance. One from them was species E. durans and others were designated as E. faecium. For 20.6% of detected isolates was in accordance with more reference strains. Other isolates were identical with reference strain on 99%. For verification of all results species-specific PCR was used and 52.9% isolates were identified as species E. faecalis, 32.4% as E. faecium and 14.7% as E. durans. Strains belonging to the species E. faecalis were identified the most reliable by all used methods

Enterococci and their ability to form a biofilm

Number of enterococci determined in raw milk cistern samples was in range of 2.95 to 4.18 log CFU.ml-1 and raw milk samples obtained from storage tanks contained enterococci count in the range of 3.04 to 4.51 log CFU.ml-1. Results of microbiological quality evaluation showed, that count of enterococci increased during cold storage of raw milk. Portion of enterococci from the total microflora of raw milk taken from cistern samples was 0.44 %, otherwise in raw milk samples taken from storage tanks portion of enterococci decreased to 0.38 %. Among enterococci isolates  E. faecalis was the predominat species in tested samples of raw milk from both cistern – 58.1 % and storage tank – 71.7 %. The following species were identified E. faecium, E. group III., E. mundtii, E. casseliflavus. It was found that 38 % E. faecalis isolates were able to form a biofilm

Selected technological properties and antibiotic resistance of enterococci isolated from milk

The aim of this work was to determine counts of enterococci in raw cow milk, to isolate and identify them, to determinate their antibiotic resistance, ability of lactose fermentation, proteolytic and lipolytic activity in different conditions of cultivation. Counts of enterococci were determined after 48 ±2 h cultivation on Slanetz-Bartley agar at 37 ±1 °C. The counts of enterococci in raw cow milk fluctuated from 1.80 x 102 to 1.77 x 103 CFU.mL-1 with average value 7.25 x 102 CFU.mL-1. Species identifications of enterococci isolates were performed using commercial EN-COCCUS test and confirmed by PCR. Majority of tested isolates (85.7%) was included to species E. faecalis. Antibiotic resistance was tested on Mueller-Hinton agar using following antimicrobial discs: vancomycin (VA) 30 µg.disc-1, gentamicin (CN) 120 µg.disc-1, erythromycin (E) 15 µg.disc-1, tetracycline (TE) 30 µg.disc-1, ampicillin (AMP) 10 µg.disc-1, teicoplanin (TEC) 30 µg.disc-1. From 13 isolates of enterococci, 1 strain was resistant to vancomycin, 1 strain to tetracycline and 1 to ampicillin, but higher prevalence of intermediate resistance of isolates was determined to tetracycline (5 strains). Ability of lactose fermentation was monitored by change of titratable acidity in UHT milk after 0, 18, 24, 40 and 48 h of cultivation at temperature 25, 30 and 37 °C. The tested strains of enterococci exhibit low milk acidifying ability. Production of proteolytic enzymes was evaluated after cultivation at temperature 7, 25 and 30 °C after 10 days on nutrient agar no. 2 with sterile skim milk (10% w/v) with pH 6.0 and 6.5. Proteolytic activity of tested enterococci strains varied depending on tested temperature and pH. Lipolytic activity was determined similarly like proteolytic activity but on tributyrin agar base with tributyrin (1% w/v). Lipolytic activity of isolated enterococci was very low. The tested strains produced halos with zone in range from 7 to 15 mm regardless of pH, cultivation time and temperature. Some of isolated and tested enterococci strains have shown suitable technological properties, but they have exhibited resistance to antibiotic

Effect of thyme and oregano aqueous tea infusions on the lipid oxidation and sensory characteristics of frankfurkters sausages

Lipid oxidation is one of the main limiting factors for the quality and acceptability of frankfurkter type of sausages. The antioxidant activity has been measured using a TBA assay. Dried oregano (Origanum vulgare) and thyme (Thymus vulgare) were purchased from a local store and kept in dark until the use. Aqueous extracts were prepared by one-step extraction with 3 g of each pulverized plant. Samples of freshly cooked sausages were evaluated by a 6 member semi-trained panel of laboratory co-workers. Panelists evaluate appearance overall texture, flavour, aroma and overall acceptability on a 6 point hedonic scale. In this work the antimicrobial and antioxidant effect of Thymus vulgare and Origanum vulgare significantly reduced (p <0.05) lipid oxidation in frankfurkters sausages on 10th day of aerobic storage. The organoleptic changes in sausages had no negative effect on the sensory value of cooked sausages. Results obtained in this work indicated the technical viability of using the oregano and thyme aqueous tea infusions in relative low concentration, which is possible to enlarge the shelf-life of fresh sausages with the desired slight alteration of the original taste parameters. Results indicate that thyme and oregano aqueous tea infusions compare to essential oils can be cheaper alternative incorporate into pork frankfurkters as natural antioxidants

The testing of sanitizers efficacy to enterococci adhered on glass surfaces

The aim of this work was to test the ability of 6 strains of enterococci to adhere on glass surfaces in environment with different content of milk residues and then to evaluate efficacy of 2 commercial sanitizers (alkaline and acidic) used in milk production. Tested enterococci were isolated from milk, dairy products and from rinse water after sanitation milking machine. Suspension of enterococci (8 log CFU.ml-1) was prepared in phosphate buffered saline (PBS), PBS with content 0.1% and 1% of skimmed reconstituted milk. Glass plates were immersed into bacterial suspension for 1 h at 37 °C. The number of enterococci adhered on glass surface in PBS achieved an average value 3.47 log CFU.mm-2, in PBS with 0.1% of milk 2.90 CFU.mm-2, in PBS with 1% of milk 2.63 CFU.mm-2. Differences between the tested files were not statistically significant (p >0.05). In the second part of work the glass plates with adhered enterococci were exposed to the effect of alkaline sanitizer (on basis of NaOH and NaClO), respectively acidic sanitizer (on basis of H3PO4). Sanitation solutions were prepared and tested according to manufacturer recommendations (concentration 0.25%, contact time 20 min, temperature   20 °C). Alkaline sanitation solution was 100% effective against all tested enterococci regardless to content of milk residues in environment. Acidic sanitation solution was 100% effective only against E. faecalisD (isolated from rinse water after sanitation). Average value of reduction of enterococci with acidic sanitation solution, which were on glass plates in environment PBS was 2.84 CFU.mm-2, in PBS with 0.1% of milk was 2.45 CFU.mm-2 and in PBS with 1% of milk was2.16 CFU.mm-2. It can be concluded, that increase of milk residues in environment decrease the adhesion of enterococci on glass surface, but also effectiveness of acidic sanitation solution

Honey characteristics after extraction and half-year storage

The aim of the study was to analyze the fresh honey after extracting and after half-year storage at room temperature. Overall, we analyzed 10 samples of rape (Brassica napus) honey coming from district Vranov nad Toplou located in the eastern Slovakia. The analysis consisted of the evaluation of the physico-chemical parameters (water content, free acidity and electrical conductivity) and microbiological evaluation (total plate count (TPC), counts of coliform bacteria, lactic acid bacteria, sporulating microorganisms and microscopic fungi). Water content, free acidity and electrical conductivity were measured according to IHC (2009), namely these parameters were detected by refractometer, titration and conductometer, respectively. We used dilution plating method for microbiological analysis. Fresh rape honey contained 18.3 ±1.0% of water. Free acidity of fresh rape honey was 12.7 ±2.0 meq.kg-1 and electrical conductivity was 0.14 mS.cm-1. After half a year of storage, water content and electrical conductivity decreased nonsignificantly and free acidity increased nonsignificantly. Stored honey samples meet the requirements of Decree 41/2012 and 106/2012. From microbiological point of view, fresh rape honey showed relatively high microbial counts. Mean values of TPC, sporulating microorganisms, lactic acid bacteria and yeasts exceeded 2.00 log cfu/g. All spotted microbial groups decreased in the stored honey comparing with the fresh honey. We found significant (p ˂0.01) differences of TPC, lactic acid bacteria and yeasts comparing the fresh and stored honey samples. Evaluating microbiological parameters, one sample of stored honey did not meet the requirements of Codex Alimentarius SR (2014). TPC exceeded the limit value. Based on the results we can conclude that all samples meet the requirements for good quality honey. Microbial counts in the honey decreased gradually. Probably, various microorganisms have important role in creation of the honey from the nectar of plants, but non-sporulating microorganisms die in the ripe honey