Antibacterially active substances

Synthesis of two hydroxy-derivatives of nalidixic acid as a result of microbial transformation was demonstrated in certain species of the genusAspergillus. Aspergillus alliaceus produced 7-hydroxy-nalidixic acid andAspergillus niger 6-hydroxy-nalidixic acid. It was demonstrated that the antibacterial activity of both hydroxy-derivatives (tested inEscherichia coli) was lower than that of the initial nalidixis acid.     

Peroxidases of different parts of the pumpkin plant (Cucurbita pepo L.)

We compared the occurrence of peroxidase isozymes in protein extract from roots, hypocotyls and cotyledons of 10 dayCucurbita pepo plants and of adult leaves of older plants by means of starch gel and polyacryl amide gel electrophoresis. We reached maximum discrimination by means of starch gel electrophoresis: 11 zones were ascertained on the cathode side and about 2 on the anode side at pH 3.1. Two zones occurred regularly:A and (the latter having a more complicated structure). ZoneD is characteristic for roots, but is it suppressed and seldom found with leaves. On the other hand zonesC ₁ andC ₂ are clearly discernible with leaves but are substantially less evident with roots. The character of anodic zoneZ is discussed later in this paper.     

The communities of the orderHalostachyetalia topa 1939 in the area of western substeppe ilmens of the Volga delta

Investigation of halophyte communities of Western substeppe ilmens of the Volga delta and their classification by theBraun-Blanquet method enabled us to distinguish 5 associations in this area:Suaedo salsae-Halocnemetum, Limonietum suffruticosi, Kalidietum foliati, Suaedo-Frankenietum, Suaedo-Petrosimonietum. These associations were united in the new allianceClimacoptero-Suaedion previously included in the orderHalostachyetalia ?opa 1939, the classPuccinellio-Salicornietea ?opa 1939.     

Interrelationships between vesicular-arbuscular mycorrhiza and rhizosphere microflora in apple replant disease

Phytotoxic micromycetes appear to be responsible for the apple replant disease (ARD). This was suppressed by the inoculation of apple-tree seedlings with some species of vesicular-arbuscular mycorrhizal (VAM) fungi—Glomus fasciculatum andG. macrocarpum. After the inoculation, growth of apple-tree seedlings improved in dependence on the type of soil, on VAM fungus species and on the ARD appearance. After 12-month cultivation, plant biomass (height, shoot and root dry masses) was markedly increased by inoculation withG. fasciculatum. Similarly, the numbers of colony forming units per unit soil (CFU) of phytotoxic micromycetes and of diazotroph bacteria (associative dinitrogen-fixing bacteria) in the rhizosphere was affected; CFU of phytotoxic micromycetes decreased, whereas CFU of the genusAzospirillum was higher. These bacteria could also serve as antagonists against phytotoxic micromycetes. It is also suggested that the ratio of CFU of diazotroph bacteria to CFU of phytotoxic micromycetes can be used as an indicator of the degree of ARD. It may be assumed that the use of some VAM fungi can replace the chemcial treatment of the soil with ARD.     

Application of the exploratory data analysis for evaluating the toxicity of chlorinated phenol derivatives by various cell models

Exploratory data analysis based on multivariate statistical analysis techniques was introduced as a new approach to expressing the toxicity of chemical substances at the simultaneous acceptance of various cell models. Using principal component analysis and cluster analysis methods the toxicity of chlorinated phenol derivatives on employing some of the cell models (chlorococcal algae, cyanobacteria, bacteria, micromycetes, plant and animal cells) was characterized. The previous empirical experience that the toxicity of chlorinated phenol derivatives will increase with a growing degree of chlorination and that the presence of the methoxy group will cause a lowering of the toxic effect was demonstrated. The relationship between groups of tests used was presented.     

Ultrastructure of cortical cells of maize root under water stress conditions

Following moderate water stress in the cortical cells of theZea mays primary roots, the condensation of the nuclear chromatin, a higher density of free ribosomes and a reduction of polyribosomes, the reduction of mitochondrial cristae, elongation of ER elements, less compact dictyosomes and inhibited production of the Golgi vesicles were observed. Severe water stress would cause more severe structural damage in the cortical cells. The more differentiated cortical cells showed more expressive ultrastructural damage when compared with the meristematic nonvacuolated cells. Similarly, the cells of the peripheral layers of the cortex suffered more from water deficit than the cells of the layers situated closer to the central cylinder.     

Removal of nitrate from water by cells ofParacoccus denitrificans in a membrane flow reactor

A new type of flow bioreactor designed to remove nitrate from water was developed. Denitrification activity of native Paracoccus denitrificans cells was used, the cells being separated from the refined medium by a semipermeable membrane. Relationships between the degree of nitrate conversion and the denitrification rate, on the one hand, and the volume flow rate and the amount of biomass, on the other, together with the results concerning denitrification during closed-circuit recirculation of the medium are discussed.     

Histological characterization of in vitro regenerated structures of Panax ginseng

Callus was induced from mature leaf lamina, petiole, stem, and main and branch root of Panax ginseng and maintained under different nutrient and light conditions. Heterogenous callus cultures differentiated organoids and/or embryoids. Embryoids that arose from callus cultures of leaf origin germinated into shoots. The occurrence of the early stages of different regenerated structures was proved on histological level.     

The effect of quaternary ammonium compounds and amine oxides on spores of bacillus cereus

The effect of 1-dodecylpiperidine 1-oxide and N,N’-bis(dodecyldimethyl)-1,2-ethane diammonium dibromide on the spores ofBacillus cereus. particularly their binding to intact spores and spores with reduced cystine bonds, was investigated. The Langmuir type of binding is involved in both cases. Both compounds decreased the thermoresistance of spores. DPNO decreased the fraction of non-germinating spores, the effect of the drug increasing with increasing concentration. This phenomenon was associated with a faster release of dipicolinic acid to the medium. Only microgermination proceeded in the presence of BDED and dipicolinic acid was released only in substantially lower amounts. Both compounds also influenced respiration.