Acta Microbiologica Bulgarica

52-58

Authors: Radin, D.

Human noroviruses are identified as the leading cause of foodborne diseases in many countries worldwide. Since 2011, in the EU the number of outbreaks caused by viruses has more than doubled, while in the US they cause 5.5 million foodborne illnesses (58%) annually. Contributing factors are some of the characteristics of human norovirus like ability to replicate to high titers, low infectious dose, persistence and stability in the environment. Noroviruses are typically spread by the fecal–oral route and transmitted by contaminated food, water or aerosols, person-to-person contact, cross-contamination from surfaces and contact with fomites. Some critical issues for contamination of foods at risk are: (i) Contamination of water sources with enteric viruses, particularly those used for agricultural practices (crop irrigation, food processing). Food at risk are fresh produce like salads and berries and bivalve shellfish due to filter-feeding what enables the concentration of norovirus from polluted water in the digestive glands. (ii) Norovirus is highly infectious and could be shed in feces at very high numbers (up to 1011 particles/g) for prolonged times (more than 3 weeks), which indicates ease of spread by food handlers. Infected foods handlers are the source of 53% of norovirus foodborne outbreaks. Foods at risk are those that need extensive handling and ready-to-eat foods that do not undergo further processing. (iii) Human noroviruses are able to attach to inert surfaces and persist for up to 28 days on common foodpreparation surfaces. Likewise is their high survival on finger pads and transfer to, for example, stainless steel surfaces and successively to foods.

65-73

Authors: Cherneva, E., Yancheva, D., Anastassova, N., Mikhova, B., Daskalova, L., Stanchev, S., Djordjevic, A., Smelcerovic, A

Three 3,6-disubstituted morpholine-2,5-diones (3,6-dimethylmorpholine-2,5-dione 15a, 3-(1-methylpropyl)-6-(propan-2-yl)-morpholine-2,5-dione 15b and 3-phenyl-6-(propan2-yl)-morpholine-2,5-dione 15c) were prepared by cyclization using N-(α-bromoacyl)-αamino esters as starting reagents. The structures of the synthesized compounds were established by IR, NMR and theoretical methods. Antimicrobial activities of the studied compounds were evaluated against two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), three Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium). Compounds 15a and 15c showed an antimicrobial effect against B. subtilis with MIC values of 2 mg/ml while compound 15b had no antibacterial effect.

79-86

Authors: Satchanska, G., Mustapha, G., Ahad, V., Ilin, D., Doycheva, A.

Lactic acid bacteria (LAB) are pronounced probiotics. They strongly improve the human immune system and produce beneficial for the human health vitamins. Lactobacilli show a strong bactericidal and antifungal activity. Due to the synthesis of many enzymes involved in the degradation of toxic substances, yogurt is known as a food favorable to longevity. Six top brands of 3.6% cow’s milk yogurt available on the Bulgarian market were examined for viable lactobacilli count, and both morphological and biochemical analysis of LAB isolates was carried out. Lactobacilli were enumerated in 1 g of yogurt via the Koch method. API 50-CH kit with 50 different metabolites was applied to examine the biochemical activity of LAB isolates and their identification. The morphology of LAB isolates was studied through light microscopy and Scanning Electron Microscopy (SEM). Our results revealed that the number of lactobacilli per g in all studied yogurt samples conformed to the Bulgarian and EU standards: in Elena yogurt - 0,7x106, in Vereia yogurt – 2.6x106, in Na baba yogurt 3.4x106, in Rodopeia yogurt - 4x106, in Parshevitza yogurt - 2.8x107, in LB yogurt 7.1x107. Slightly under the standard was the number of lactobacilli in Elena yogurt. 12 LAB isolates were cultured and identified as Lactobacillus delbrueckii ssp. bulgaricus, being positive in the degradation of only four out of totally 50 metabolites: D-glucose, D-fructose, D-mannose and D-lactose. In three out of six samples, the score of affiliation reached 99% while for the remaining three samples it was lower. The morphology analysis of the isolates via light microscopy and SEM showed characteristics typical of lactobacilli. The examined six top yogurt brands available on the Bulgarian market are safe for consumption and contain Lactobacillus delbruekii. subsp. bulgaricus at the standard concentrations recommended by the EU.

94-99

Authors: Popova, R., Popov, B.

On the basis of own studies and literature data, the most common alternatives to healthy diets and the subsequent health risk effects are discussed. The experimental studies presented show that in reduced or irregular eating patterns the deficiency of nutrients or their irregular intake activates the systems of absorption of energetic components of food at the expense of the absorption of the structure ones. This can explain the so-called ”yo-yo effect” when normal eating habits are resumed. The authors also discuss the “phenomenon of satiety”, characterised by suppression of the systems for hydrolysis and transport of a given nutrient during a period of intensive and prolonged intake. At the same time a deficient intake of a nutrient stimulates the systems for its absorption. On account of this, eating regimens are discussed, where the intake of one nutrient is increased at the expense of another Such types of diets can cause serious metabolic disorders with harmful health consequences. Different options of vegetarian diets are analysed with emphasis on the risk health effects of the diets with permanent exclusion of animal products. The scientific view on “split diet” is discussed and some principles of its use are explained.