LABORATORY BACTERIAL VIRULENCE, RESISTANCE AND NEW ANTIMICROBIAL AGENTS – The Stephan Angeloff Institute of Microbiology

Epidemiology, epizootology and prevention of yersiniosis, salmonellosis, colibacillosis and mycobacterial infections in domestic and wild animals.
Detection, quantification and typing of food zoonotic pathogens of medical importance in products of animal origin using molecular biological methods based on polymerase chain reaction (PCR).
Antibiotic susceptibility in various causative agents of food zoonoses and pathogenic fungi of the genus Candida. Phenotypic and genotypic resistance profile.
Screening of natural products with plant and microbial origin, as well as of newly synthesized compounds, for antibacterial and antifungal activities.
Study of the influence of biologically active substances on the quorum-sensing systems, responsible for bacterial virulence at the protein and genetic level (biofilm formation and gene expression).
Isolation of microorganisms from various natural habitats, decomposing paper, plant and textile waste, in order to protect the environment and their implementation in industry.
Molecular genetic and population-structural analysis of Mycobacterium bovis strains from cattle in Bulgaria.

SELECTED PUBLICATIONS:

Le Guern, A. S., Savin, C., Angermeier, H., Brémont, S., Clermont, D., Mühle, E., Orozova, P., Najdenski, H., Pizarro-Cerdá, J. (2020). Yersinia artesiana nov., Yersinia proxima sp. nov., Yersinia alsatica sp. nov., Yersina vastinensis sp. nov., Yersinia thracica sp. nov. and Yersinia occitanica sp. nov., isolated from humans and animals. International Journal of Systematic and Evolutionary Microbiology, 70(10), 5363-5372, 2020. IF: 2.4; Q1
Yakub, A. Toncheva, V. Kussovski, R. Toshkova, A. Georgieva, E. Nikolova, N. Manolova, I. Rashkov “Curcumin-PVP loaded electrospun membranes with conferred antibacterial and antitumoral activities”, Fibers and Polymers, 21(1), 55-65, 2020. IF: 1.439; Q2
Georgieva, M. Popova, L. Dimitrova, B. Trusheva, D. T. L. Phuong, N. T. P. Lien, H. Najdenski, V. Bankova “Phytochemical analysis of Vietnamese propolis produced by the stingless bee Lisotrigona cacciae”, PloS one, 14(4), e0216074, 2019. IF: 2.776; Q1.
Mantareva, C. Gol, V. Kussovski, M. Durmuş, I. Angelov “Impact of water-soluble zwitterionic Zn (II) phthalocyanines against pathogenic bacteria”, Zeitschrift für Naturforschung C, 74(7-8), 183-191, 2019. IF: 1.00; Q3
Gevrenova, M. M. Zaharieva, A. D. Kroumov, L. Voutquenne-Nazabadioko, D. Zheleva-Dimitrova, V. Balabanova, H. M. Hajdenski, S. Konstantinov “Gypsophila saponins enhance the cytotoxicity of etoposide in HD-MY-Z lymphoma cells”, Food and Chemical Toxicology, 133, 110777, 2019. IF: 3.775; Q1
B. Scheufele, C. L. Hinterholz, M. M. Zaharieva, H. M. Najdenski, A. N. Módenes, D. E. G. Trigueros, C. E. Borba, F. R. Espinoza-Quiñones, A. D. Kroumov “Complex mathematical analysis of photobioreactor system”, Engineering in Life Sciences, 19(12), 844-859, 2019. IF: 1.936; Q2
P. Popova, B. S. Trusheva, P. T. Nedialkov, I. Tsvetkova, D. P. Pardo-Mora, H. Najdenski, O. A. Torres-Garcia, J. M. Sforcin, V. S. Bankova, V. S. “New Δ-tocotrienol derivatives from Colombian propolis”, Natural Product Research, 1-8, 2019. IF: 2.060; Q2
Trusheva, H. Petkov, M. Popova, L. Dimitrova, M. Zaharieva, I. Tsvetkova, H. Najdenski, V. Bankova ““Green” approach to propolis extraction: natural deep eutectic solvents”, Comptes rendus de l’Académie bulgare des Sciences, 72(7), 897-905, 2019. IF: 0.321; Q2
H. Najdenski, V. Ilyin, P. Angelov, V. Hubenov, D. Korshunov, Kussovski, L. Dimitrova, I. Simeonov “Laboratory biodegradation of potential cellulose wastes generated during long-term manned space missions”, Ecological Engineering and Environment Protection, 1, 71-78, 2019. ISSN 1311-8668
Dimitrova, M. M. Zaharieva, M. Popova, N. Kostadinova, I. Tsvetkova, V. Bankova, H. Najdenski “Antimicrobial and antioxidant potential of different solvent extracts of the medicinal plant Geum urbanum L.”, Chemistry Central Journal, 11(1), 113, 2017. IF: 2.442; Q2
Stoykova, M. Chochkova, G. Ivanova, N. Markova, V. Enchev, I. Tsvetkova, H. Najdenski, M. Stícha, T. Milkova “Ultrasound-assisted green bromination of N-cinnamoyl amino acid amides – structural characterization and antimicrobial evaluation”, Journal of Molecular Structure, 1135, 144-152, 2017. IF: 1.25; Q2

ACHIEVEMENTS:

Samples from a total of 679 forest wild birds migrating along the Eastern European migration route were collected and tested for the presence of food pathogens of the genera Campylobacter, Yersinia, Salmonella and Listeria and species Escherichia coli, Staphylococcus aureus and Francisella tularensis, as well as blood-borne pathogens species Coxiella burnetii, Borrelia burgdorferi and Brucella This study aimed to determine the prevalence of these pathogens is the largest conducted in Bulgaria to date. Our data show that wild birds can transmit pathogens such as Campylobacter, Yersinia, E. coli, Listeria and Brucella. On the other hand, birds migrating along the Eastern European migration route are not involved in the transmission of bloodstream pathogens C. burnetii and B. burgdorferi, but represent a risk for the spread of brucellosis.
The role of migrating pelicans of the species Great White Pelican (Pelecanus onocrotalus) and Greater White-Fronted Goose (Anser albifrons) for the dissemination of food and aquatic zoonotic pathogens, as well as ticks, carriers of such on the Bulgarian Black Sea Coast and the Eastern European migration route, was studied for the first time. The onocrotalus, migrating through the territory of Bulgaria, is a carrier of pathogenic species of the genus Campylobacter and pathogenic strains of E. coli, which creates conditions for the induction of food-borne infections caused by these pathogens. In contrast, the populations of A. albifrons wintering in the area of the town of Shabla are not important carriers of food and aquatic zoonotic pathogens.
New specific protocols have been developed for the rapid detection and identification of Mycobacterium avium and paratuberculosis in tissue samples from affected internal organs of domestic and wild animals and artificially contaminated with mycobacteria milk and fecal samples.
Real-time PCR protocol has been developed for the detection and quantification of pathogenic strains of Yersinia enterocolitica and pseudotuberculosis species in raw milk using various genes encoding virulence factors as a target for primer design.
A LAMP protocol has been developed for rapid, specific and sensitive detection of Yersinia enterocolitica in tonsils and feces from pigs for slaughter. More than 700 samples from different pig farms were examined to monitor the spread of the pathogen. Positive isolates were serotyped, biochemically characterized and sequenced.
For the first time the antimicrobial activity and the mechanism of action of different extracts and fractions from the medicinal plant Geum urbanum in collaboration with the Laboratory “Cytotoxicity and signal transduction” were determined (The Stephan Angeloff Institute of Microbiology – BAS). From the roots were isolated and characterized chemically novel compounds for the species (3,3’-di-O-methylellagic acid-4-O-β-d-glucopyranoside, tormentic acid and niga-ichigoside F1) and genus Geum (3-O-methylellagic acid-3’-O-α-3’’-O-acetylrhamnopyranoside and 3-O-methylellagic acid-3′-O–α-2″-O-acetylrhamnopyranoside) in collaboration with the Laboratory “Chemistry of Natural Products” (Institute of Organic Chemistry with Centre of Phytochemistry – BAS).
The in vitro cytotoxicity of the plant on normal transformed and malignant cell lines, as well as its antiviral and radical-scavenging potential were studied (collaboration with Laboratory “Cytotoxicity and signal transduction”; The Experimental Chemo-therapy and Molecular Pharmacology Laboratory (Faculty of Pharmacy, Medical University – Sofia), Laboratory “Experimental Chemotherapy of Enteroviral Infections” and Laboratory of Cellular Microbiology (The Stephan Angeloff Institute of Microbiology – BAS), and Department of Pathology (Institute of Experimental Morphology, Pathology and Anthropology with Museum – BAS). In vivo experiments on acute and subacute toxicity in mice of ethyl acetate extract from aerial parts of the plant were performed (collaboration with Faculty of Medicine, Sofia University “St. Kliment Ohridski”), as well as a skin irritation test on rabbits. It is planned to conduct additional research and develop the extract in the form of a food additive.
Bacterial communities from various natural habitats capable of degrading lignocellulosic substrates in aerobic, microaerophilic and anaerobic conditions have been isolated and characterized. They could find application both on the Earth and in long-term manned flights. This will contribute to the development of space microbiology, a new scientific field for Bulgaria. The studies were conducted in collaboration with the Laboratory “Bioremediation and Biofuels” and The Space Research and Technology Institute – BAS.