New molecular complexes of heterocyclic bis-adducts with bacterial lectins: synthesis and structure-activity relationship studies

A strongly antitumour effect has been discovered for lectins of Bacillus bacteria [Bacillus subtilis 668(1 + 2)IMV, Bacillus polymyxa 102(1 + 2) KGU] and for their molecular complexes with some heterocyclic bis-adducts of unsubstituted benzimidazole and 6-methyluracile for the first time. These were tested on the tumours: Lymphosarcoma Plissa, Sarcoma 45, Carcinosarcoma Yokera 256. A new convenient method for the preparation of the heterocyclic bisadducts of imidazole, benzimidazole, uraciles with 1,1,1-trifluoro-2-bromo-2-chloroethane is described. The reactions are catalysed by the 18-crown-6-complex.     

Lactic Acid Bacteria and Yeasts as Means of Decreasing Wine Acidity

Two hundred monocultures of lactic acid bacteria and 30 associations of yeasts and lactic acid bacteria have been studied. A stable association was developed which was capable of decreasing wine acidity. The association contained two species of bacteria, Leuconostoc oenosand Pediococcus pentosaceus, and the yeast Saccharomyces cerevisiae. The physiology of the microorganisms was studied, and their effects on the chemical composition of wines were determined.     

Conformational polymorphysm of G-rich fragments of DNA Alu-repeats. II. The putative role of G-quadruplex structures in genomic rearrangements

Three evolutionary conserved (G-rich) sites of Alu repeats (PQS2, PQS3, and PQS4) could form in vitro stable inter- and intramolecular G-quadruplexes (GQs). Structures and topologies of these GQs were elucidated using spectral methods. The study of self-association of G-rich Alu fragments performed using a FRET-based method revealed dimeric GQ formation from two distally located sites (PQS2)₂, (PQS3)₂ or PQS2?PQS3 within one extended single stranded DNA. Using DOSY NMR, AFM microscopy and differential CD spectroscopy it has been demonstrated that oligomer PQS4 (folded into a parallel intramolecular GQ) forms stacks of quadruplexes stabilized by stacking interactions of external G-tetrads. Comparative analysis of the properties of various GQs suggests involvement of two universal general mechanisms of GQ-dependent genomic rearrangements: (i) formation of dimeric GQs from fragments of different molecules; (ii) formation of GQ-GQ-stacks from pre-folded intramolecular parallel GQs from different strands. Thus, association of G-rich Alu motifs with sensitivity to double-strand breaks and rearrangements may be attributed not to structural features of G-rich Alu fragments, but also to their high abundance.     

Fungal Deterioration of Barrier Concrete used in Nuclear Waste Disposal

Fungal biogeochemical activity over a long-term scale may have negative environmental consequences for the management of barrier materials used in nuclear waste disposal. Fungal deterioration of barrier concrete was studied in microcosms simulating a heterogeneous environment with an external source of nutrients for the fungi. Fungi successfully colonized barrier concrete, generally avoiding granite aggregates, and biochemically (by excretion of protons and ligands) and biomechanically deteriorated the concrete. Fungi dissolved the cement matrix leaching structural elements and accumulating them within the fungal biofilm and associated microenvironment. Oxalate-excreting Aspergillus niger formed abundant calcium oxalate crystals on the concrete and encrusting fungal hyphae.     

Growth efficiency of thielavia terrestris mycelial structures

The growth energetic efficiency (η) of two mycelial forms of Thielavia terrestris (pellets and diffused form) was studied by different methods. η Values determined by the pulse method are similar for the two forms, but the values determined by C balance for pellets were lower than those for diffused mycelium. These balance data prove that pellets yield more extracellular products than the diffused mycelium form, which is also confirmed by experimental data for different amounts of carbon in the culture fluid. Growth efficiency can be determined by various methods based on the principles of mass and energy balance. The estimates most frequently used are the biomass and substrate balances. However, growth efficiency determination according to oxygen balance (particularly by the pulse method) is simpler and more accurate; as it makes possible the immediate fixation of changes in the physiological condition of microorganisms and the determination of complex substrate utilization efficiency [1]. Earlier the possible use of this method for evaluating the growth efficiency of heterotrophic bacteria [2], hyphalic and yeast forms of microscopic fungi [3] was shown. The aim of the present study is the comparative investigation of the growth efficiency of two mycelial structures (hyphalic and pellets) by different methods as well as by pulse additions.     

Double substrate-oxygen limitation of the growth of methanol oxidizing yeasts]

The influence of the double substrate-oxygen limitation on the specific rate of growth of two strains of methanol oxidizing yeast Candida boidinii was studied in a chemostat. On the basis of the bottle-neck theory in the metabolic chain of biochemical reactions, relations between the specific rate of yeast growth and limiting concentrations of methanol and oxygen are suggested. They agree with a certain mechanism of enzymic bisubstrate reactions.