Acta Microbiologica Bulgarica

Number 37(1), 2021

3-9
Dipyridamole as an Interferon Inducer

Authors: Galabov, A.S.

Abstract

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Number of views: 119

We described the pyrimidine derivative dipyridamole (DP) as an interferon (IFN) inducer in culti¬vated in vitro lymphoid cells, administrated orally in mice and in humans attaining high IFN titres within 24 hours. Gut-associated lymphoid tissue was identified as the inducer target. IFN-antagonistic period was established. Three double-blind placebo trials (more than 6000 participants proved that DP acts as a prophy¬lactic for influenza and viral acute respiratory diseases. Experimental evidence proved that the IFN-induc¬ing activity of DP is due to its capacity to inhibit cAMP phosphodiesterase. Additionally, DP demonstrates a marked inhibitory effect on the replication of a broad spectrum of viruses. It was established that DP-in¬duced IFN production in humans is strongly dependent of compound pharmacokinetics. DP activities were followed and described in lupus erythematosus, chronic pulmonary diseases, liver diseases, in ophthalmology, dermatology (herpesvirus and papillomavirus infections) and AIDS. Special attention was given to a possible DP’s effect in COVID-19 patients.

10-21
Food Safety Culture Among Food Handlers in Slovenia

Authors: Jevšnik, M., Bobnar, S., Šadl, M.S., Raspor, P.

Abstract

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Number of views: 139

The study aimed to investigate the extent to which food handlers´ perceptions of food safety culture differs based on their demographic characteristics. A cross-sectional paper-based survey was conducted among food handlers in catering establishments in Slovenia. Data were collected using validated question¬naires. Statistical analysis was performed using SPSS soft¬ware. The factors of food safety culture with the highest assessed level of agreement were self-satisfaction and environment support, whereas work pressure and risk judgment exhibited the lowest level of agreement. There were statistically significant differences between food handlers’ participation in food safety training courses entitled “Hygiene minimum” and food safety culture factors: management, communication and work pressure. An important statistically significant difference was observed between the number of years spent at the current workplace and the environ¬ment support. Those who attended the course entitled “Hygiene mini¬mum“ show a higher level of agreement for the management factor (M = 5.79, SD = 0.81) compared with those who did not attend this kind of training (M = 5.41, SD = 0.72). The study highlighted the weaknesses of food safety culture in catering establishments and propose improvements in order to enhance food safe¬ty culture. We established how demographic characteristics of the respondents affect the shaping of food safety culture. The questionnaire proved to be an effective tool in the assessment of food safety culture among food handlers in catering establishments in Slovenia. Our findings could assist food business operators in their efforts to develop strategies that will more effectively contribute to food safety culture.

22-26
ARDRA Analysis on Biodiversity of Lactobacilli Isolated from Bulgarian Raw Buffalo Milk

Authors: Beev, G., Michaylova, M., Dinev, T., Naydenova, N., Tzanova, M., Urshev, Z.

Abstract

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Number of views: 145

Lactic acid bacteria are widespread in nature and occur naturally as indigenous microflora in raw milk. Considering that buffalo milk is an excellent medium for the growth of a large variety of lactic acid bacteria, the aim of this study was the isolation of Lactobacillus spp. strains from raw buffalo milk orig¬inating from different areas and their species identification, using Amplified Ribosomal DNA Restriction Analysis (ARDRA) and a set of five reference strains of the most frequently isolated Lactobacillus species. From the analysis of the patterns generated after treatment with HaeIII it was found that 24 (88.8%) of the isolates had profiles that matched the reference 16S rDNA of Lactobacillus casei. The restriction profiles of the remaining three isolates (12.2%) did not match any of the reference strains and they were identified by API 50 CHL as Lactobacillus fermentum. This indicates that L. casei is highly adaptive and dominates in raw buffalo milk regardless of the climatic conditions and the method of raising animals.

27-33
Molecular Identification of Fusarium spp. Isolated from Wheat Grain Based on Sequencing of Internal Transcribed Spacer (ITS) Region

Authors: Gencheva, D., Beev, G.

Abstract

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Number of views: 143

Molecular identification via Internal Transcribed Spacer region (nrDNA-ITS) sequencing of Fusari¬um spp. isolates from wheat grain originated from Stara Zagora region was performed for the first time in Bulgaria. А total of 60 wheat grain samples (Triticum aestivum) were preliminarily morphologically iden¬tified at the genus level as Fusarium spp. The rDNA-ITS region of all isolates was successfully amplified and the PCR products obtained were directly sequenced. After a comparison of detected sequences with the NCBI database, members of three different fungal genera (Fusarium, Chaetomium and Alternaria) were identified. Among the Fusarium isolates, F. tricinctum was prevailing, followed by F. poae. A total of three isolates, F. proliferatum, F. graminearum and F. equiseti, were presented with a single probe. The shortest genetic distance (0.004) was detected between F. tricinctum isolates. On the basis of genetic distances, fun¬gal isolates were grouped into two main clusters – one comprising F. tricinctum isolates and F. proliferatum, and the second including F. equiseti, F. graminearum and F. poae. It could be concluded that the rDNA-ITS genome region of the genus Fusarium may be used as a suitable marker for early detection, accurate and reliable identification of Fusarium spp. contamination of wheat. The timely and accurate information would assist in the selection of appropriate approaches for control of Fusarium infections and possible mycotoxin contamination of agricultural products.

34-45
Phytochemical Composition, Antioxidant, Antimicrobial Potential and GC-MS Analysis of Crude and Partitioned Fractions of Nigella sativa Seed Extract

Authors: Adebayo-Tayo, B.C., Briggs-Kamara, A.I., Salaam, A.M.

Abstract

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Number of views: 191

The study aimed to investigate the phytochemical, antioxidant, antimicrobial potential and GC-MS analysis of crude and different fractions of Nigella sativa seed extract. Crude methanol extract of N. sativa seed was obtained, the phytochemical components, antioxidant and antimicrobial potential of the seed were evaluated and the crude extract was partitioned using different solvents. Antimicrobial activity was determined and GC-MS analysis of the fractions was conducted. Saponins, flavonoids, alkanoids (19.8%, 41.6% and 82%), tannins, anthraquinones, terpenoids and steroids were present while cardiac glycosides were not detected. The hexane and chloroform fraction yielded 60.17% and 0.42% from the partitioned crude ex¬tract, respectively. DPPH (2, 2-dipheniyl-1-picrylhydrazyl), total phenolic content and ferric reducing antioxidant power (40.37, 20.1 and 48.4 %) increased in a dose-dependent manner. N. sativa fractions had varied antibacterial activity against the test bacteria and fungi. Staphylococcus aureus ATCC29213 and methicillin-resistant S. epidermidis3 were highly susceptible (60.0 mm and 56.0 mm) to chloroform fractions while Trichophyton sp. and Candida tropicalis had the highest susceptibility (50 mm) to the hexane fraction. A total of 24 dis¬tinct phyto-components were identified, and 9, 8, 7, 3 and 4 compounds were found in the hexane, meth¬anol, ethyl acetate, chloroform fractions and the crude extract. The compounds were 2-Chloroethyl vinyl sulfide, 11-Octadecenoic acid, methyl ester, Cyclononene, 3,8-Dioxatricyclo[5.1.0.0(2,4)] octane, 4-ethe¬nyl-, 7-Hydroxy-3-(1,1-dimethylprop-2-enyl)coumarin, Trimethylsilyl-di(timethylsiloxy)-silane among others. The crude, hexane and chloroform (%) fractions contained 99.3%, 96.42% and 97.90%, respectively, of Trimethylsi-lyl-di(timethylsiloxy)-silane. In conclusion, the N. sativa seed extract contains good phytochemicals, anti¬oxidant and varied antimicrobial activities against the test pathogens.

46-50
Antiviral Activity of Rapana thomasiana Hemocyanin against Bovine Rotavirus

Authors: Vilhelmova-Ilieva, N., Idakieva, K., Doumanova, L., Galabov, A.S.

Abstract

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Number of views: 118

The aim of this study was to investigate the antiviral activity of hemocyanin isolated from natural marine snail Rapana thomasiana (RtH) and its structural subunit RtH-1 against Bovine rotavirus (BRV). R. thomasiana is widespread in the Black Sea, Mediterranean Sea and Marmara Sea, and hemocy¬anins have received extensive research in recent years due to their antitumor, antibacterial, antiviral and antifungal activities. We examined RtH from R. thomasiana and its subunit (RtH-1) for its effect on the replication of Bovine rotavirus (BRV), Negovan strain, in Madin-Darby bovine kidney (MDBK) cells. The experiments were performed at non-toxic concentrations of both products - lower than the maximum tolera¬ble concentration (MTC) (10 mg/mL). The anti-BRV activity of RtH and RtH-1 was determined in two time intervals - at 48 hours and 120 hours of exposure. At 48 hours, the activity of both products was significant, showing dependence on the concentration of the applied substance. In RtH-1 the most noticeable decrease in viral titer with Δlg = 2.25 was observed at concentrations higher than 1 mg/mL, and in RtH the same effect was observed at a concentration of 3.2 mg/mL. In the second time interval (120 hours), the activity of both products decreased significantly. It could be concluded that conformational changes in proteins are the most likely reason for the clear antiviral activity at 48 hours, followed by a decrease in activity as time progresses to 120 hours. On the other hand, virus molecules can also undergo conformational changes over time.