The aim of this study was to test the antimicrobial activity of propolis, bee pollen loads and beeswax samples collected in the year 2009 from two locations in Slovakia to pathogenic bacteria, microscopic fungi and yeasts. The antimicrobial effect of the bee product samples were tested using the agar well diffusion method. For extraction, 99.9% and 70% methanol (aqueous, v/v) and 96% and 70% ethanol (aqueous, v/v) were used. Five different strains of bacteria, i.e. Listeria monocytogenes ccM 4699, Pseudomonas aeruginosa ccM 1960; Staphylococcus aureus ccM 3953; Salmonella enterica ccM 4420, Escherichia coli ccM 3988, three different strains of microscopic fungi, Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, and seven different strains of yeasts Candida krusei, Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, Geotrichum candidum, Rhodotorula mucilaginosa, were tested. After 48 hours S. aureus was the bacterium most sensitive to the 70% ethanol extract of pollen, A. fumigatus was the most sensitive microscopic fungus (70% ethanol) and C. glabrata the most sensitive yeast (70% methanol). Microorganisms most sensitive to propolis extracts were L. monocytogenes, A. fumigatus (70% ethanol) and G. candidum (70% methanol). Most sensitive to beeswax extracts were E. coli, A. niger and C. tropicalis.

The aim of this study was to examine the effect of propolis extracts on the microbial colonization of chicken gastrointestinal tract in vivo. The propolis was administered to both feed mixtures in various amounts except of the control group. The addition of 150 mg propolis to 1 kg of feed was included in the first experimental group, the addition of 450 mg.kg⁻¹ in the second experimental group, the addition of 600 mg.kg⁻¹ the third experimental group and 800 mg kg⁻¹ in the fourth one. The highest count of faecal enterococci was found in the third group (8.6 cfu.g⁻¹) where 600 mg of propolis to 1 kg was added to the feed mixture. The highest count of lactobacilli was detected in the fourth experimental group (8.83 cfu.g⁻¹) where was 800 mg of propolis added to 1 kg of feed mixture and number of Enterobacteriaceae genera count was found in control group (8.73 cfu.g⁻¹). With RTQ PCR detected species from the genus Enterococcus were: E. avium, E. casseliflavus, E cecorum, E. faecalis, E. faecium, E. gallinarum, E. hirae and E. malodoratus and from genus Lactobacillus were: Lactobacillus crispatus, L. acidophilus and L. salivarius. With MALDI TOF MS Biotyper from Enterobacteriaceae genera were identified Citrobacter braakii, Raoultella ornithinolytica, Serratia fonticola, Escherichia coli and Klebsiella oxytoca. Antimicrobial activities In vitro of six species of bacteria isolated from gastrointestinal tract of chickens were also tested. The best antimicrobial effect of Citrobacter braakii on ethanolic propolis extract in all concentrations were found.

The study aimed to assess the antifungal activity of twenty–five essential oils (EOs) and the potential synergistic activity of the most effective EOs against significant indoor fungi of the genus Aspergillus [A. fumigatus (KBio–122), A. flavus (KBio–134), A. terreus (KBio–145) and A. niger (KBio–202)]. The chemical composition of all EOs was evaluated by the gas chromatography coupled with mass spectrometry (GC/MS) and gas chromatography with flame ionization detector (GC–FID) analysis. The antifungal susceptibility of EOs was evaluated by using the broth microdilution method. The most effective EOs were selected to determine the minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) at a concentration range from 256 to 0.125 μg/mL. For the synergistic activities, the most effective EOs were tested using the chessboard pattern. The most sensitive strain to treatments with essential oils alone and in the combination of EOs was A. flavus (KBio–134). The chessboard assay showed that combinations of lemongrass and thyme EOs proved the most potent synergistic antifungal activity (FICI = 0.1875) against A. fumigatus (KBio–122). The synergy displayed by a combination of some EOs may be used to control fungal growth or increasing resistance to available synthetic antifungals, consequently permitting the reduction of their most active doses.

The present study was conducted to investigate the effect of natural feed additives, namely bee pollen extract, propolis extract and probiotic preparation, on technological properties of meat in order to evaluate the meat quality of Ross 308 broiler chickens. The feeding of chickens (180 pcs) lasted for a period of 42 days. The experiment was carried out without segregation between the genders. The chickens were randomly divided into 4 groups. The control group was fed a basal diet, whereas the other three groups were fed diets supplemented with natural additives, i.e. bee pollen extract at level of 400 mg.kg-1 of feed mixture, propolis extract at level of 400 mg.kg-1 of feed mixture, and probiotic preparation based on Lactobacillus fermentum (1.109 CFU per 1 g of bearing medium) in an amount of 3.3 g added to water (for 30 pcs chickens until 21 days of age, for 20 pcs chickens from 22nd to 42nd day of age) given to group E1, group E2 and group E3, respectively. The feed mixtures were produced without any antibiotic preparations and coccidiostatics. During the whole period of experiment, the broiler chickens had ad libitum access to feed and water. The following technological properties were examined: cooling loss (after 24 h of storage at 4 °C), freezing loss (after 3 months of storage at -18 °C), roasting loss (performed on roasted meat that was stored at -18 °C for 3 months before thawing), colour parameters based on CIELab system (the L*, a*, b* values of raw breast and thigh muscle), and tenderness (as shear force of roasted breast and thigh muscle). We have made a finding, that the examined additives had only little impact on meat quality in most of the investigated parameters, except the significant increase (p ≤0.05) in redness (a*) values and the slight decrease in roasting loss and shear force determination after propolis extract supplementation. Therefore, it may be inferred that propolis extract has been shown as the most appropriate feed additive among the applied supplements.

Aflatoxin B₁ (AFB₁) is one of the most toxic mycotoxins. One of the producers of AFB₁ is Aspergillus flavus. Therefore, its rapid identification plays a key role in various sectors of the food and feed industry. MALDI-TOF mass spectrometry is one of the fastest and most accurate methods today. Therefore, the aim of this research was to develop the rapid identification of producing and non-producing strains of A. flavus based on the entire mass spectrum. To accomplish the main goal a different confirmatory MALDI-TOF MS and TLC procedures such as direct AFB₁ identification by scraping from TLC plates, A. flavus mycelium, nutrient media around A. flavus growth, and finally direct AFB₁ identification from infected wheat and barley grains had to be conducted. In this experiment, MALDI-TOF mass spectrometry with various modifications was the main supporting technology. All confirmatory methods confirmed the presence of AFB₁ in the samples of aflatoxin-producing strains of A. flavus and vice versa; AFB₁ was not detected in the case of non-producing strains. Entire mass spectra (from 2 to 20 kDa) of aflatoxin-producing and non-producing A. flavus strains were collected, statistically analyzed and clustered. An in-depth analysis of the obtained entire mass spectra showed differences between AFB₁-producing and non-producing strains of A. flavus. Statistical and cluster analysis divided AFB₁-producing and non-producing strains of A. flavus into two monasteries. The results indicate that it is possible to distinguish between AFB₁ producers and non-producers by comparing the entire mass spectra using MALDI-TOF MS. Finally, we demonstrated that if there are established local AFB₁-producing and non-producing strains of A. flavus, the entire mass spectrum database identification of aflatoxigenic A. flavus strains can be even faster and cheaper, without the need to identify the toxin itself.

Klebsiella pneumoniae carbapenemase (KPC)-producing bacteria is a group of highly dangerous antibiotic resistant Gram-negative Enterobacteriaceae. They cause infections associated with significant morbidity and mortality. Therefore, the rapid detection of KPC-producing bacteria plays a key role in clinical microbiology. Matrix assisted laser desorption/ionization time-of- flight (MALDI-TOF) is a rapidly evolving technology that finds application in various clinical, scientific, and industrial disciplines. In the present study, we demonstrated three different procedures of carbapenemase-producing K. pneumoniae (KPC) detection. The most basic model of MALDI-TOF instrument MS Microflex LT was used, operating in the linear ion-positive mode, commonly used in modern clinical laboratories. The first procedure was based on indirect monitoring of carbapenemase production with direct detection of hydrolyzed carbapenem antibiotic degradation products in the mass spectrum. The second procedure was based on direct detection of bla_KPC accompanying peak with an 11,109 Da in the mass spectrum of carbapenemase-producing K. pneumoniae (KPC), which represents the cleaved protein (pKpQIL_p019) expressed by pKpQIL plasmid. In addition, several unique peaks were detected in the carbapenemase-producing K. pneumoniae (KPC) mass spectrum. The third procedure was the identification of carbapenemase-producing K. pneumoniae (KPC) based on the protein fingerprint using local database created from the whole mass spectra. By comparing detection procedures, we determined that the third procedure was very fast and relatively easy. However, it requires previous verification of carbapenemase-producing K. pneumoniae (KPC) using other methods as genetic bla_KPC identification, detection of carbapenem degradation products, and accompanying peak with 11,109 Da, which represents cleaved pKpQIL_p019 protein expressed by pKpQIL plasmid. Detection of carbapenemase-producing K. pneumoniae using MALDI-TOF provides fast and accurate results that may help to reduce morbidity and mortality in hospital setting when applied in diagnostic situations.