Effect of temperature and soil moisture content on the colonization of the wheat rhizosphere by antipytopathogenic Bacillus Cohn

Vegetative experiments showed that the population density of antiphytopathogenic bacillar species introduced into the rhizosphere of spring wheat seedlings essentially depended on soil temperature and not on the soil moisture content. As a rule, the population of introduced bacilli increased with temperature. Under both low and optimal soil moisture contents, introduced bacilli were efficiently acclimated in the wheat rhizosphere.     

Similar hypotensive responses to resistance exercise with and without blood flow restriction

Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances.     

Application of Bacillus-antagonists for biocontrol of fungi degrading raw wood

Species composition of micromycete complexes colonizing aspen, birch, and pine wood was studied. Calculation of the Sorens-Tchekanovsky similarity coefficients showed that these complexes shared a high degree of similarity. They were dominated by the representatives of the genera Penicillium, Paecilomyces, Trichoderma, and Rhizopus. Some antagonistic bacilli inhibited growth and development of wood-decay fungi in vitro and led to the formation of spheroplasts on growing hyphae. A study of possible involvement of bacillary mycolytic enzymes in the inhibition of wood-decay fungi demonstrated selectivity of their lytic effect, which was determined by the genus and species of micromycetes and did not correlate with their relative resistance to antagonists.     

Microbiota of the Kinderlinskaya cave (South Urals,Russia)

The mesophilic and psychrotolerant microbiota of the air, soil, water, and bottom sediments of the Kinderlinskaya cave (South Urals, Russia) and the factors affecting the structure of microbial communities were investigated. The pattern of microbial distribution in soils was shown to depend on both the configuration of the cave and the level of recreational load. The lowest numbers of bacteria and micromycetes were found in the poorly visited, difficult-to-access sites. Coliform bacteria were revealed in all soil and sediment samples and in some water samples. Micromycetes belonged to 19 genera, with Geomyces pannorum as the dominant species. Air movement was shown to be the main factor affecting the density of the aerial microbiota.     

The role of chitinase in antifungal activity of Bacillus sp. 739]

Investigation of the crude extracellular chitinase of Bacillus sp. 739, an antagonist of phytopathogenic fungi, discerned a relationship between the chitinase and antifungal activities of this bacterium. Purified chitinase lost its ability to inhibit the growth of micromycetes. The antagonistic (antifungal) activity of crude chitinase was found to be located in a low-molecular-weight fraction of the enzyme, which does not possess chitinase activity. Both crude and purified chitinase were able to lyse the cell walls of intact mycelium. Accordingly, it may be inferred that the antagonistic activity of Bacillus sp. 739 against micromycetes is largely determined by low-molecular-weight nonenzymatic substances whereas the role of chitinase is to utilize chitin, which is ubiquitously present in soil.     

Lytic enzyme complex of an antagonistic Bacillus sp. X-b: isolation and purification of components

Bacillus sp. X-b, a biocontrol agent against certain plant pathogenic fungi, secretes a complex of hydrolytic enzymes, composed of chitinase, chitosanase, laminarinase, lipase and protease. Homogenized mycelium of basidiomycete Macrolepiota procera induced activities of these enzymes more effectively than colloidal chitin or partially purified cell walls of another basidiomycete Polyporus squamosus. Subjected to a multi-step purification, the specific activity of chitinase increased 36-fold, chitosanase 69-fold, lipase 44-fold and laminarinase 15-fold. Partially purified chitinase showed two major bands with molecular masses of 46 000 and 35 000 on sodium dodecyl sulfate–polyacrylamide gel electrophoresis while chitosanase and lipase appeared as single bands with molecular masses of 27 000 and 62 000, respectively.     

Wide-range antifungal antagonism of Paenibacillus ehimensis IB-X-b and its dependence on chitinase and beta-1,3-glucanase production

Previously, we isolated a strain of Bacillus that had antifungal activity and produced lytic enzymes with fungicidal potential. In the present study, we identified the bacterium as Paenibacillus ehimensis and further explored its antifungal properties. In liquid co-cultivation assays, P. ehimensis IB-X-b decreased biomass production of several pathogenic fungi by 45%-75%. The inhibition was accompanied by degradation of fungal cell walls and alterations in hyphal morphology. Residual medium from cultures of P. ehimensis IB-X-b inhibited fungal growth, indicating the inhibitors were secreted into the medium. Of the 2 major lytic enzymes, chitinases were only induced by chitin-containing substrates, whereas beta-1,3-glucanase showed steady levels in all carbon sources. Both purified chitinase and beta-1,3-glucanase degraded cell walls of macerated fungal mycelia, whereas only the latter also degraded cell walls of intact mycelia. The results indicate synergism between the antifungal action mechanisms of these enzymes in which beta-1,3-glucanase is the initiator of the cell wall hydrolysis, whereas the degradation process is reinforced by chitinases. Paenibacillus ehimensis IB-X-b has pronounced antifungal activity with a wide range of fungi and has potential as a biological control agent against plant pathogenic fungi.     

Antagonistic activity of bacteria from Bacillus genus against dermatophyte fungi

Antagonistic properties of the strain Bacillus subtilis IB-54 with respect to dermatophyte fungi Trichophyton rubrum, T. mentagrophytes var. gypseum, Microsporum canis was studied. The studied strains of bacilli effectively inhibited growth and development of dermatophytes when were cultivated on the media containing different carbon sources. Experiments on laboratory animals showed that B. subtilis IB-54 displayed no virulence, toxicity, and toxigenicity and can be considered as perspective object for development of antimycotic drugs.     

On separation and identity of fern antheridiogens

Chromatographic studies show that the hormones controlling antheridiuminduction in the fern species Pteridium aquilinum (Polypodiaceae),Anemia phyllitidis and Lygodium japonicum (Schizaeaceae) aredifferent molecular entities. SCHRAUDOLF's report that gibberellic acid induces antheridiain A. phyllitidis and L. japonicum was confirmed. The activityspectrum of GAs towards species of different fern families stronglyresembles that of the native Anemia antheridiogen. However,the native antheridiogens of A. phyllitidis, and of Lygodiumjaponicum, are more species-selective in their action than isGA₃. Preliminary studies have yielded no conclusive evidenceon whether the native antheridiogens are gibberellins. (Received August 21, 1967; )