In a 10-year field experiment, the influence of fertilizing, cultivating, and crop rotation measures on the C-content of the soil, humus quality of the organic soil substance, and the yield was investigated.
The non motile Gram-positive spore-forming bacteria are much more adsorbed on the bentonite than the motile Gram-negative rods. The motile bacteria adjance to clays in the phases of their rapid multiplication only. The dependence of the clay adsorption of motile microbes by the substrate and/or intermediate adsorption has been suggested.
In three profiles of a semi-gley soil under the floodplain forest, variations were studied in the activities of invertase, amylase, cellobiase, cellulase, proteases, and phosphatases. In the surface soil layer, enzymatic activity was found affected by the soil moisture at a significant level, whereas in the deeper soil layers the influence of aeration was more effective. Moreover, significant correlations could be detected between the amount of available nitrogen and protease activity, while the water-soluble phosphorus acted as a repressive agent on the activity of phosphatases. Existence of correlations between the numbers of microbes and enzymes could be demonstrated for invertase and proteases only.
1. Active ingredients retarding the carbon-transformation of straw (TCP, Thiuram, TBTO) also retard the nitrification. Their active period depends on the concentration and on the presence of organic matter. High doses of urea can inhibit the nitrification as well. 2. The activity of urease and the ammonification could not be influenced by adequate doses of the tested active ingredients. 3. The species of bacterium Azotobacter fixing the nitrogen from the air were inhibited by TCP, urea and D-chloramphenicol and promoted by Thiuram and WTZ II 277 after a short period of inhibition. 4. The fungi are very important in the biological nitrogen fixation after manuring straw and in prevention of nitrogen leaching in the autumn. 5. The sufficient concentration of the active ingredients to inhibit the nitrification are lower than the fungicidal concentrations. The soil bacteria could even not be restrained by doses of 5000 ppm. The bacilli were more retarded in presence of organic matters than in a not manured soil.
The possibilities to influence the decomposition of straw and lucerne by fungicidal, bactericida and total acting microbiocides, respectively, were tested comparatively. Total or fungicidal acting substances caused the heaviest inhibition of decomposition at both the organic matters. The efficiency of active ingredients was greater at straw than at lucerne. The reason of the different inhibiting effects is that the lucerne which is easy to decompose and rich in protein can be decomposed alone by the physiologically active bacteria, which are resistant to active ingredients. That means the decomposition of lucerne takes place without the help of fungi. However, the fungi sensible to the active ingredients play a more important role in the straw decomposition. Therefore substances with permanent fungicidal effects are sufficient for the inhibition of straw decomposition. Inhibiting the decomposition of greenmanure presumes permanent acting fungicidal and bactericidal substances. Such substances are not available at present. Systemic fungicides did not influence the decomposition of plants for green-manure due to their limited scope of activity.
Two hundred colonies which showed positive reaction on the plates prepared for the phosphate-dissolving bacteria from control soil rhizosphere soils and rhizoplane samples of maize, peas, or cotton were isolated at random. Fifty isolates were selected as the most efficient isolates according to their capability for increasing the amounts of available phosphorus in the media with corresponding decreases in pH values. The percentage of the most efficient isolates differed according to type of plant and location of isolation. Not only the morphological types of the phosphate-dissolving bacteria differed in soil and in rhizosphere, but they also differed in the rhizosphere soil of each special plant. Morphological differences in the isolates from rhizosphere soil and from rhizoplane samples of the same plant were also occurring. The abundance of mycelial-forming bacteria and of aerobic sporeformers in Egyptian soil is important as they are well known to resist adverse conditions, such as high temperature and dryness to which our soils are subjected most time of the year.
An electron microscope study has shown that the spread of Fusarium sulphureum through potato tuber tissue occurs not only intracellular but also intercellular. The spread of hyphae effected both mechanical and enzymatical. The study of cells neighbouring hyphae shows degeneration of protoplasm. Intercellular spaces of infected tissue are filled with a dark substance. It seems that these substances are fragments of cell walls which are macerated by Fusarium enzymes.
At least three gluconic acid forming enzymes were identified in cell-free extracts of Aspergillus niger: glucose oxidase (EC 1.1.3.4), a glucose dehydrogenase (EC 1.1.99.10), and an enzyme or a mixture of enzymes catalyzing the cleavage of 6-phosphogluconate into gluconate and inorganic phosphate. 2,6-dichlorphenolindophenol was one of the hydrogen acceptors in vitro of the glucose dehydrogenase. Some properties of this enzyme (Km values, pH-dependence, substrate and hydrogen acceptor specificity), as determined in cell-free extracts, were found to be in good agreement with properties described in literature for a glucose dehydrogenase which has been purified from Aspergillus oryzae. The formation of Pi from 6-phosphogluconate and other phosphate esters was found to have an optimum between pH 7 and 8 , and another below pH 4. This suggests that it is catalyzed by an alkaline and an acid phosphomonoesterase (EC 3.1.3.1, 3.1.3.2), both enzymes exhibiting only low substrate specificity. The influence of extraction and assay buffers on the activity of gluconate forming enzymes was investigated. Loss of activity during preparation of cell-free extracts, as calculated from loss of activity storage of cell-free extracts at 4 degrees C, was found to be lower than 4%. Purified glucose oxidase added before homogenization was found in the extract almost quantitatively.
In Primorye Territory, USSR, cucumber mosaic virus (CMV-I), arabis mosaic virus (AMV), raspberry ringspot virus (RRSV), and tomato ringspot virus (TRSV) were identified on berry crops (currant, raspberry, honeysuckle).
