Addition of medicinal plant Ungernia victo ris extract to bacterial nutrient medium rises significantly yield of cell biomass and target protein of strains ITG1 (producer of recombinant NH 2terminal fragment of βgalactosidase) and ITG71Δ (producer of recombinant chimerical polypeptide with immunological properties of HIV protein Env1). When relatively poor LB medium is used, low concentrations of extract (0.25, 0.5 and 1%) do not ensure effect of stimulation. At the same time the presence of extract in higher concentrations (2.0, 5.0 and 10%) acts to rise further increasing of biomass level and total content of target protein on unit of medium volume for both strains. So the results of experiments carried with use of LB medium demonstrate principle ability of U. victoris extract for raising final yield of target product at the expense of two mechanisms — increase of biomass yield and growth of percentage of recombinant polypeptide in total cell protein. Unlike the results obtained in LB medium, extract of 2.0, 5.0 and 10% concentrations in enriched medium that is in use usually for industrial cultivation of strainsproducers demonstrates even stable tendency to inhibition of final yield of biomass and target polypeptide aside from stimulate. For all that addition of U. victoris extract to enriched medium in more low concentrations (0.25–1%) results as a rule in significant yield increasing of target proteins for both strains. Data obtained correspond to our data received earlier for plasmidless strains and prove general regularities according to that ones addition of medicinal plant extract in high concentrations to poor medium and in low concentrations to enriched one facultates significant rise of biomass and target protein yields per unit volume of cultivation medium.

Optimization of culture media is considered to be one of the ways to increase biomass output of bacterial cells as well as a base product at cultivation of all types and purposes. In connection with the development of the biotechnology industrya, search of the new components of nutrient solution and their optimum ratio with the base composition of the medium and corresponding properties of the cultivated object is becoming increasingly important. Addition of Ungernia victoris extract to bacterial nutrient medium optimizes its composition and enables to increase production of E. coli biomass. Statistical reliable exceeding of biomass production of M17 and HB101 strains in LB medium occurs only at higher concentrations of extract (5–10%) while biomass production of JM109 strain increases at all tested concentrations (0,5–10%). The highest biomass yield of all three strains corresponds to extract concentration of 10%. The influence of U. victoris extract on growth of bacterial strains in enriched medium differs from its influence on the same strains in LB medium. Biomass increase happens at low concentrations of extract (0.25–1%)and it is not such significant as its increase in LB medium. Starting with extract concentration from 2% and to 10%, the tendency towards biomass decrease for M17 and HB101 strains and lower biomass increase for JM109 strain as compared with 0.25–1% concentrations takes place. Thus, it is possible to get improvement of bacterial biomass production by means of plant extract using both poor and enriched medium. Optimal quantity of the added extract fluctuates depending on medium composition and peculiarities of object of growth.

A principle possibility of antitumour activity test in bacterial system represented by Escherichia coil of the wild type and its MS2-induced mutant has been shown. The initial bacterial strain is an indicator of toxic properties of the tested substances and the mutant one is a specific test-culture modelling a tumour cell. The comparison of the data described for eucaryotes with the data obtained using the proposed bacterial test system confirms an adequate response of both strains to the substances with the proved antitumour properties. The data are considered as very promising for the further improvement of this test system towards its application for primary screening of antitumour substances.

In the system of cation-induced E. coli transformation by the plasmid pBR322 the effects of the extract derived from the biomass of cultured cells of U. victoris on the correlation between yield of transformants, viability of CaCl2 - treated cells and plasmid DNA conformation alterations has been investigated. The data obtained have been compared with effects of some salts of one- and divalent metals on the same parameters. The presence of different mechanisms of the variations of cell population viability and yield of transformants depending on utilization of salts or plant extracts has been shown.

РЕЗЮМЕЧрез генетични методи е получен вариант на фага λ, способен да заразява бактериалната култура и да натрупва един МS2-подобен λ -фаг. Той съответства на РНК-фагите по структурата на вириона и е в кръга на гостоприемниците, но се различава от тях по вида на негативлите колонии и електрофоретичното отнасяне на нуклеиновата киселина.