Morphology, electrokinetic characteristics and the effect on biofilm formation of carrageenan:chitosan polyelectrolyte complexes.

Carrageenan:chitosan (CG:CH) polyelectrolyte complexes (PEC) were obtained and the effect of the initial components ratio on formation was studied by dynamic light scattering, atomic force microscopy (AFM) and electrokinetic measurements. Positively charged PEC particles (average ζ-potential 40.2 mV) were formed, provided that the polycation was present in excess in the complex and was stabilized by chitosan amino groups. According to the AFM data, chitosan was located on the surface of the carrageenan fibers. In PEC where carrageenan prevailed, the number of unbound sulfate groups decreased when the chitosan content increased, this resulted in a decrease in the PEC negative surface charge (from -92.4 to -55.6 mV). In this case, AFM showed that chitosan was incorporated into the network structure of carrageenan and breaks it at a CG:CH ratio of 1:0.5 w/w. Complexes with a high content of kappa-CG inhibited biofilm formation by Gram negative and Gram positive microorganisms.

[BIOLOGICAL ACTIVITY OF YERSINIA PSEUDOTUBERCULOSIS TOXINS].

AIM: Study of effect of heat-labile (HLT) and thermostable (HST) lethal toxins of Yersinia pseudotuberculosis on the development of embryos of sea urchin Strongylocentrotus intermedius, processes of biosynthesis of nucleic acids and protein in embryo cells and activity of nucleoside- kinases of sea urchin. Materials-and methods. Y pseudotuberculosis strains 2517 (pYV-) and 512 (pYV48MD, pYV82MD) were used for isolation of HLT and HST Gametes and embryos of sea urchin S. intermediuswere used to carry out the experiments and isolate nucleoside-kinases. RESULTS: , Both of the studied toxins of Y pseudotuberculosis possessed, spermiotoxic effect and reduced fertilizing ability of sea urchin spermies. HLT LD50 was 1 µg/ml, and HST - 2 µg/ml. Toxins affected the development of embryos of sea urchin resulting in severe morphologic damages, cessation ofthe development of embryos at early stages of embryogenesis, destruction of cells and death of embryos. Wherein; damaging effect of HLT was observed at lower concentrations compared with HST HLT inhibited DNA and RNA biosynthesis at concentrations of 1-2 µg/ml. HST did not affect biosynthesis of nucleic acids even at high concentrations, but inhibited protein biosynthesis in sea urchin embryos. HLT did not reduce the level of inclusion of labeled amino acids into embryo cells. HLT had inhibiting effect on the activity of thymidine- and uridine-kinase of sea urchin, whereas HST did not affect these enzymes. CONCLUSION: Both of Y pseudotuberculosis protein toxins affect the development of sea urchin embryos, however, mechanisms of action of HLT and HST on embryos and processes occurring in them differ.