Folia Microbiologica

Aspergillus flavus produced approximately 50 U/mL of amylolytic activity when grown in liquid medium with raw low-grade tapioca starch as substrate. Electrophoretic analysis of the culture filtrate showed the presence of only one amylolytic enzyme, identified as an α-amylase as evidenced by (i) rapid loss of color in iodine-stained starch and (ii) production of a mixture of glucose, maltose, maltotriose and maltotetraose as starch digestion products. The enzyme was purified by ammonium sulfate precipitation and ion-exchange chromatography and was found to be homogeneous on sodium dodecyl sulfate— polyacrylamide gel electrophoresis. The purified enzyme had a molar mass of 52.5±2.5 kDa with an isoelectric point at pH 3.5. The enzyme was found to have maximum activity at pH 6.0 and was stable in a pH range from 5.0 to 8.5. The optimum temperature for the enzyme was 55°C and it was stable for 1 h up to 50°C. TheKm andV for gelatinized tapioca starch were 0.5 g/L and 108.67 μmol reducing sugars per mg protein per min, respectively.

Following the intravenous inoculation of chickens with large doses of livingFrancisella tularensis andListeria monocytogenes organisms, a virus inhibitor appeared in their serum. The first traces of the inhibitor were found four hours and the maximum levels eight and 24 hours after inoculation with a bacterial suspension. The administration of heat-inactivated microorganisms did not induced formation of the inhibitor. The dynamics of formation of the inhibitor and its properties resembled those of virus interferon.

Bubble size distribution was found to be represented by a modified log-normal distribution with 3 parameters. The parameters are simple functions of suspension properties,viz. surface tension, viscosity and density, and a function of superficial gas rate. Correlations are presented, enabling the prediction of the distribution constants (and thus of the bubble size distribution) from the system properties and gas rate. Model translucent systems can be used, having identical apparent system properties as real suspensions in experimental work. A computer algorithm is presented for (i) prediction of bubble size distribution, defining the region of formation of spherical bubbles, (ii) converting particle size distribution into volume distribution, (iii) determining the actual gas volume from a hold-up correlation, and (iv) giving the surface area of the system of a given predicted distribution.

The toxic effect of citric and succinic acids on the germination of the pycnidiospores ofBotryodiplodia theobromae, mycelial growth and the killing rate of theB. theobromae spores was investigated. The percentage inhibition of germination of viable fungal spores by 0.01% succinic or citric acid ranged between 51.6 and 58.1%, respectively.B. theobromae was found to grow in 2% malt extract broth at 28°C at the rate of 0.13 CFU/h. Citric acid exhibited a higher killing rate of 0.26 CFU/h and was more effective against the germination of the fungal spores. At concentrations of 0.3% and above, citric acid could be used as pre- and post-infectional fungicide.

Detoxication of 2,4-dichlorophenoxyacetic acid (2,4-D) in samples of chernozem soil was determined by a biological test and the time course of production of14CO2 a product of microbial degradation of 2-14C-2,4-D, was measured during 38-d incubation at 28°C in the dark. Enrichment of the soil with glucose (1000 ppm), two exocellular bacterial glucan and glucomannan polysaccharides (750 ppm), or a mixture of glucose with (NH4)2SO4 (C:N=5∶1) brought about acceleration of both detoxication and mineralization of 2,4-D (50 ppm) added simultaneously with the saccharides. Mineralization of the saccharides always preceded the degradation of the herbicide. The lag phase of 2,4-D mineralization, did not exceed 3 d. In samples with saccharides the doubling time of the mineralization activity in the exponential phase of the process was substantially shortened and the mineralization of 2,4-D was accelerated even when the soil was inoculated with a suspension of soil in which microbial 2,4-D decomposers had accumulated. The extent, of mineralization was not affected by the presence of saccharides (about 1/3 of the introduced radioactive carbon was transformed into14CO2). All saccharides had a similar effect which reflected an increase in the overall bacterial count and in the relative abundance of bacterial 2,4-D decomposers. The role of other mechanisms such as co-metabolism in the stimulation of the degradation process is discussed.

Sixty-five samples of cerebrospinal fluid (CSF) were evaluated using an automated cytoflow method with the CD-Sapphire hematology analyzer in order to investigate possible relationships between cell population patterns and diagnostic groups and better understand the biology of neurological disease. A basic panel of CD markers, including CD3/4/8/19/138/HL A-DR, was used to analyze CSF samples from clinical and laboratory confirmed cases of multiple sclerosis, neuroborreliosis, viral and bacterial neuro-infective diseases, malignant infiltrations of meninges and scavenger macrophagic reactions of the central nervous system. The principles of immune response and the contribution of cytological ‘disease-related patterns’ for these nosological entities are described. The distinct patterns of lymphocyte subpopulations in neuroborreliosis appear to be characteristic and could possibly serve as diagnostic indicators. Further verification and research will be necessary to clarify the significance and nature of CD4+ CD8+ positive subset in cerebrospinal fluid.

The ultrastructure of saprophytic and parasitic spores of the AscomyceteClaviceps purpurea (Fr.) Tul. was studied. Considerable differences were found to exist between the saprophytic and parasitic spores as to morphology and fine structure. The reason for the different ultrastructural morphology is probably connected with the intensity of cell metabolism. Whereas the parasitic spores obtained from the honeydew possess the character of a resting cell with a thick electron-dense cytoplasm, abundant lipid bodies, few mitochondria, an underdeveloped and hence little active endoplasmic reticulum and with a homogenous thick cell wall, the saprophytic spores appear as cells with higher metabolic rate, containing more numerous mitochondria, a thinner cytoplasm, a highly developed endoplasmic reticulum, fewer lipid bodies and abundant large vacuoles as well as frequently a new wall layer.

Callus cultures ofMedicago sativa were treated with a preparation of elicitor from the mycelium ofFusarium oxysporum. The ability of the elicitors to induce the formation of antimicrobial substances was tested biologically. The preparation of the cell walls ofF. oxysporum induced the occurrence of substances with a strong antimicrobial effect. Thermal sterilization had no effect on the activity of the elicitor.