Detoxification of AM-241 solutions by humic substances: bioluminescent monitoring.

The study addresses the effect of humic substances on marine luminous bacteria Photobacterium phosphoreum exposed to Am-241 (3,000 Bq L(-1), water solution). Luminescent intensity of the bacteria was applied as a marker of their physiological activity. Humic substances have been found to reduce the effect of Am-241 on luminescence, decrease damage to cells, and change distribution of Am-241 between bacterial cells and intercellular media. It was shown that water-soluble humic substances, being products of natural transformation of organic substances in soil and bottom sediments, can serve as protecting agents for water microorganisms exposed to alpha radionuclides.

Extracellular Oxidase from the Neonothopanus nambi Fungus as a Promising Enzyme for Analytical Applications.

The extracellular enzyme with oxidase function was extracted from the Neonothopanus nambi luminescent fungus by using mild processing of mycelium with ß-glucosidase and then isolated by gel-filtration chromatography. The extracted enzyme is found to be a FAD-containing protein, catalyzing phenol co-oxidation with 4-aminoantipyrine without addition of H2O2, which distinguishes it from peroxidases. This fact allowed us to assume that this enzyme may be a mixed-function oxidase. According to gel-filtration chromatography and SDS-PAGE, the oxidase has molecular weight of 60 kDa. The enzyme exhibits maximum activity at 55-70 °C and pH 5.0. Kinetic parameters Km and Vmax of the oxidase for phenol were 0.21 mM and 0.40 µM min-1. We suggest that the extracted enzyme can be useful to develop a simplified biosensor for colorimetric detection of phenol in aqueous media, which does not require using hydrogen peroxide.

Development and morphological features of biofilms formed by transgenic and wild type strains of Bacillus subtilis.

The study addressed the ability of the transgenic strain (TM) B. subtilis 2335/pBMB 105 (KmrInf+) to form biofilms on the surface of liquid media of various compositions, inoculated with vegetative cells and spores. The morphological features of these biofilms do not differ from those of the films formed by the recipient strain (WT) B. subtilis 2335 (Kms). However. the TM and the natural one differ in the dynamics of biofilm formation and the cellular composition of the films. Biofilms of the TM are formed earlier, develop at a higher rate, but decompose later than the films of the WT. When the medium is inoculated with vegetative cells, sporulation in the biofilms of both strains undergoes glucose repression; no such effect is observed when the medium is inoculated with spores. The TM does not form films when the medium is inoculated with spores and supplemented with glycerin and kanamycin.

Biocompatibility of polyhydroxybutyrate microspheres: in vitro and in vivo evaluation.

Microspheres have been prepared from the resorbable linear polyester of beta-hydroxybutyric acid (polyhydroxybutyrate, PHB) by the solvent evaporation technique and investigated in vitro and in vivo. Biocompatibility of the microspheres has been proved in tests in the culture of mouse fibroblast cell line NIH 3T3 and in experiments on intramuscular implantation of the microspheres to Wistar rats for 3 months. Tissue response to the implantation of polymeric microspheres has been found to consist in a mild inflammatory reaction, pronounced macrophage infiltration that increases over time, involving mono- and poly-nuclear foreign body giant cells that resorb the polymeric matrix. No fibrous capsules were formed around polymeric microparticles; neither necrosis nor any other adverse morphological changes and tissue transformation in response to the implantation of the PHB microparticles were recorded. The results of the study suggest that polyhydroxybutyrate is a good candidate for fabricating prolonged-action drugs in the form of microparticles intended for intramuscular injection.