DEPARTMENT OFMORPHOLOGY OF MICROORGANISMS AND ELECTRON MICROSCOPY

  • The ultracytochemical localization of acid phosphatase in nongerminating and germinating conidia of the fungus Humicola lutea is established for the first time. The distribution in the mycelia is clarified.
  • Original evidence is obtained about the fine structural changes of model Gram-positive and Gram-negative bacteria under the action of rhamnolipid-biosurfactant with surface-active properties.
  • The ultrastructural peculiarities, the growth and reproductive capacity of producers of thermostable exo-inulinase and cyclodextrin glucanotransferase immobilized on different matrices (polysulphone membranes, agar gel) are characterized.
  • A correlation is determined between the ultracytochemical localization of succinate dehydrogenase of some bacteria and the changes in the lipoproteid content of their membranes under the action of Lubrol W.
  • Original cytochemical evidence is collected for the cell-surface and intracellular distribution of polysaccharides with defined lectin-binding capacity in some Gram-negative and Gram-positive bacteria.

DEPARTMENT OF MICROBIAL BIOCHEMISTRY

  • For the first time it is found that the Pomorie mud is an inductor of enzyme neuraminidase secretion at pathogenic genera Vibrio and Aeromonas because of the presence of sialic acids in the mud.
  • From different microbial strains were isolated, identified and characterized biosurfactants with effective surface and emulsifying properties and were found promising for application in biomedicine, bioremediation and biotechnology.
  • Microbial transformation of the steroid compounds sitosterol and androstenedione was performed by resting cells of Mycobacterium sp. and Rhodococcus sp., respectively, in a single phase organic solvent based medium.
  • A modified chemostat technique called titrostat was developed for selective isolation and continiuous flow cultivation of rapidly growing bacteria utilizing toluene vapours as a single source of carbon and energy.
  • A simple and rapid test for differentiation of aerobic from anaerobic bacteria was developed applicable for determination of the respiratory type of pure cultures isolated from different areas of the environment.

DEPARTMENT OF MICROBIAL GENETICS

  • The physiological and biochemical peculiarities of the original yeast strain Trichosporoncutaneum R57, which is highly active in degrading many aromatic and aliphatic compounds – toxic pollutants of the environment were investigated. The biochemical analysis of the first three enzymes of the catabolic pathway of degrading phenol in carbonless media enhanced the elucidating of their key role in the process. A system for homologous and heterologous protoplast fusion and protoplast transformation of Trichosporon cutaneum R57 strain was elaborated. A specific oligoneucleotide probe was applied for the identification of microbial strains with the potential of degrading toxic aromatic compounds, isolated from polluted soils and waters. Dot-blot hybridization analysis for the identification of catabolic genes, coding enzymes with phenol-hydroxilase activity was carried out.
  • Original approaches to the molecular-taxonomic characterization of lactic acid producing bacteria and the rapid monitoring of Lactobacilli from different ecological niches were developed.
  • The genetic, physiological and other factors, controlling the sexual process of the yeast Hansenula polymorpha were investigated. Two special types of homothalism were uncovered: a copulation potential in all possible combinations and sporulation of haploid strains.

DEPARTMENT OF MICROBIAL BIOSYNTHESIS AND BIOTECHNOLOGY

  • A method for production of extra cellular α-galactosidase was developed by submerged cultivation of Aspergillus niger M47 , Penicillium chrisogenum LN33 and Humicula lutea 1205 on the medium, composed by wastes from food industry. The method was submitted for patent(Patent Application№ 109202/23.06.2005Aleksieva, P., Nacheva, L., Tchorbanov, B., Bratovanova, E. Method for obtaining of α-galactosidase (by free cells);PatentApplication№ 109929/02.08.2007Institute of Microbiology, Institute of Organic Chemistry, Aleksieva, P., Nacheva, L., Tchorbanov, B., Bratovanova, E., Yakimova, B. Method for obtaining of α-galactosidase (by immobilized cells).
  • A Lab biotechnology for galanthamine production by Leucojum aestivum shoot culture was developed. This is the first bioreactor process reported for production of Galanthamine by in vitro plant system.
  • A detailed “know-how” for production of L-lysine and a Lab biotechnology for production of L-valine were developed.
  • From culture medium of a thermophilic strain two indole alkaloids (microbiareton and microbiaeratinin) were isolated and their cytotoxic and antialgic activities were established.
  • An alkaline hydrolysate from animal wastes was obtained and their influence on chemical and microbiological properties of the poor soils were investigated. The obtained results outlined the possibilities for its application as an organic fertilizer.
  • The growth of methylotrophic yeasts Hansenula and Pichia on glucose, methanol and glycerol as carbon source was investigated. The presence of catalase and superoxide dismutase (SOD) activity in fractions of mitochondria, cytosol and peroxisomes were investigated. It was established that peroxisomal catalase was located in the mitochondrial matrix and SOD( besides the typical places for localization- mitochondria and cytosol)was detected in peroxisomes as well.
  • The proteolytic system of starter lactobacteria was characterized and it was established that this system is a criterion for their participation in starters for milk products.
  • In situ baceriocins production of LB. bulgaricus BB18 and LB. lactis BCM5 was studied and their strain compatibility with two technological strains S. thermophilus 11A and Lb. bulgaricus LX1 was demonstrated for forming starters for fermented milks with health benefits.
  • The strain Streptomyces sp., producer of antibiotic complex, was identified by hemotaxonomic and genetic methods as Streptomyces iakurus DSM 41873. The antibiotic complex is composed of 5 new components, which were characterized by their molecular masses and chemical structures.
  • The colloid properties of glucomannan, synthesized by psychrophilic stain were studied. The comparison of the cream emulsions with glucomannan and those with emulsifiers rofetan and arlacel ( used in cosmetic industry) showed that they were with equal stability.
  • The yeast strain, producer of phytase was isolated from Antarctic samples. The appropriate culture medium and parameters of cultivation were established for high production of phytase. The enzyme kinetics and properties were determined as well.
  • By flow cytometry the genom sizes of the cells of Beta vulgaris intact plants and hairy root cultures were determined. It was established that in contrast to the primary plant tissues, the obtained hairy roots are mixoploids., due to several cycles of endoreduplication. Such difference currently is not reported in the available scientific literature.

DEPARTMENT OFMICROBIAL ECOLOGY

  • Original baker's yeast strains - Saccharomyces cerevisiae were selected. These strains have high trehalose content and high maltase activity.
  • Method for quantitative determination of biotin applying specially selected methanol utilizing yeast strain was elaborated.
  • Strains of Aspergillus niger producers citric and gluconic acids under double limitation of nitrogen and phosphorous during their cultivation were selected.
  • The mathematical model of growth and production of citric acid on different carbon sources was developed.
  • The strains bioindicators and detectors of heavy metal and pesticides pollution were selected.
  • Microbial association degrading phenol was selected

DEPARTMENT OF MYCOLOGY

  • A sizeable fungal collection was developed along with the isolation of strains from temperate and extreme environments, including Antarctica.
  • New evidences were given for the relationship between oxidative stress and various environmental challenges (heavy metals, heat- or cold-shock, cell immobilization). Evaluation of specific oxidative stress biomarkers (generation of reactive oxygen species, cyanide resistant respiration, oxidative damaged proteins, storage carbohydrates) and enzyme antioxidant defense were carried out.
  • Unusual existence of Cu/Zn-SOD in mitochondrial intermembrane space (IMS) was evidenced. This is the first identified naturally glycosylated enzyme, isolated from IMS.
  • High effective technology forbiosynthesis of naturally glycosylated Cu/Zn-SOD by the fungal strain Humicola lutea 103 was elaborated. The novel enzyme was fully characterized and used in in vivo animal models for the demonstration of its protective effect against Graffi tumor and influenza virus infection. This enzyme improves fertility of ram and bull spermatozoa during liquid storage and cryoconservation.
  • New information about biotechnological potential of Antarctic fungi was obtained.
  • Due to the current knowledge about morphology and biochemistry of the filamentous fungi, as well as the professional experience some methods concerning the preservation of natural polymers from fungal biodegradation were developed.

DEPARTMENT OF EXTREMOPHILIC BACTERIA

  • A moderate thermophilic bacterial strain Bacillus sp. UG-5B with benzonitrilase activity was isolated from polluted industrial waters. The benzonitrile degradation was realized via nitrilase pathway. Due to the high enzyme thermostability of free or immobilized cells as well as the broad substrate specificity, the isolated strain, Bacillus sp. UG-5B could have a potential application in chemical synthesis or various detoxification processes.
  • An effective synthesis of cyclodextrin glucanotransferase was realized by magnetic biocatalysts containing cells of Bacillus circulans ATCC 21783 and enzyme with a high specific activity was obtained.
  • A new isolated bacterial strain representing novel species, Anoxybacillus rupiensis, was isolated from Bulgarian hot spring.
  • The originally isolated from Bulgarian hot spring Bacillus stearothermophilus strain was described as the only producer of thermostable gellan lyase reported up to now. Its thermostability determines the possibility for running industrial processes at temperature higher than 60°C in which temperature gellan is soluble.

DEPARTMENT OF PATHOGENIC BACTERIA

  • Bacterial-host interactions (invasion, persistence, intracellular survival, as well as the bioenergetic mechanisms ensuring these processes) were characterized. Pathogenesis of experimental melioidosis, listeriosis, yersiniosis, salmonelosis, etc. and immune response of different hosts were established in details.
  • Yersinia outer membrane proteins have been isolated and used in improved ELISA and immunoblot tests for routine laboratory diagnosis of natural yersiniosis in humans and pigs and experimental yersiniosis of rabbits.
  • Aiming development of new generation of live carrier vaccines, clinical, immunological and pathomorphological examinations were carried out after experimental oral infections of rabbits with two wild and four genetically constructed mutantс of Yersinia enterocolitica O:8. A lower virulence and bacterial load of viscera, weaker morphological changes, better immunogenicity and well expressed tissue tropism to the lymphoid tissue of the mutant strains wzzGB and sodA-314 in comparison with mutants 8081-R2, wbcEGB and wild strains WA-314 and 8081-L2 were established.
  • The role of Yersinia LPS antigen in induction of reactive arthritis was proved in experimental mouse and rat models.
  • The incidence and transmission of multidrug-resistant Mycobacterium tuberculosis strains in Bulgaria were examined by using advanced molecular epidemiological methods and population structure analysis. The multidrug resistant and hypervirulent Beijin strain was not found in Bulgaria. The results contribute to control the global spread of multidrug tuberculosis worldwide.
  • Thephotoinhibitoryeffectcouldbeusedinthepracticeforphotosterilizationof contaminated with enterobacteria water ecosystems.
  • The method of PCR-DGGE was optimized and successfully applied for direct detection and typing of Campylobacter jejuni and C. coli in caecal samples of broilers without preliminary enrichment. This method allows reliable and fast detection and identification of pathogenic Campylobacters being causative agent No.1 of food-born infections in humans.

DEPARTMENT OF VIROLOGY

DEPARTMENT OF IMMUNOLOGY

  • The ability of the opportunistic yeast Candida albicans to induce reactive arthritis in normal and in predisposed individuals has been studied. The relationship between infections and rheumatic diseases has been analyzed in detail with the aim of developing new therapeutic approaches in rheumatic diseases.
  • The immunomodulatory properties of coumarin, 7-hydroxycoumarin, yeast superoxide dismutase and molluscan hemocyanins have been described. They have therapeutic potential as antitumor agents as well as for the prophylaxis of infectious diseases.
  • Preparing of an educational program for life-long learning in the fields of medical microbiology and immunology for nurses, laboratory technicians, etc. has been created with the participation of scientists from four European countries (Leonardo da Vinci Programme of EC).
  • Discovery of previously unknown mechanisms of the immunomodulatory activity of pooled IgG (IVIg) in autoimmune patients.
  • Development of experimental improved “next-generation” pooled human immunoglobulin preparation with an improved therapeutic effect in systemic inflammatory diseases.
  • Describing of the immunomodulatory potential of normal pooled human IgM in autoimmune and inflammatory diseases.
  • Development of a novel approach for silencing selectively autoreactive disease-associated B cells in autoimmune diseases.
  • Describing of the phenomenon of inflammation-induced enhancement of IgG antigen binding polyreactivity.
  • Development of DNA vaccines with a new type of build-in adjuvanticity.

RESEARCH GROUP FOR MATHEMATICAL MODELING AND COMPUTER SCIENCES

  • Models (deterministicandneural) of theanaerobicdigestionoforganicwastes (specificandinmixtures) and of the production of the enzyme superoxide dismutase
  • Optimisationandcontrolalgorithmsfortheanaerobicdigestionoforganicwastes (specificandinmixtures), accompanied by biogas yield, as well as forthe production of the enzyme superoxide dismutase
  • Laboratorybiogastechnologiesbasedontheanaerobicdigestionoforganicwastes (specificandinmixtures)

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