The concentrations of bacteria and moulds in the air decreased to undetectable levels in experiments with ozone and UV radiation. When exposed, in all of the species tested, viability on surfaces varied depending on the concentration and species of micro-organisms. At a concentration of less than 50 cm Ϫ2 , all species of micro-organisms were susceptible to the ozone and UV treatments at the laboratory table. At the concentration of 10 5 cm Ϫ2 , the most effective was ozone for Escherichia coli and Pseudomonas aeruginosa, while Bacillus subtilis was relatively more resistant. Compared with ozone treatment, the application of UV radiation was less effective on micro-organisms including methicillin-resistant Staphylococcus aureus when the micro-organisms were placed under the laboratory table.
Using the gas chromatography-mass spectrometry (GC-MS) method we found in Streptomyces cinnamonensis saturated fatty acids of iso- and anteiso- types, cyclopropyl acids, and unsaturated fatty acids where the double bond position was determined by MS of their pyrrolidine derivatives.
Variability in the production of nogalamycin by Streptomyces nogalater var. nogalater was followed in untreated and mutagenized populations of the standard strain NRRL 3035 and its spontaneous variant K-18 using the method of agar blocks with subsequent tests under submerged conditions. In both strains the most active variants were obtained by natural selection without mutagenic treatment; in this way productivity increased by 108% after two selection steps. Treatment with UV-radiation did not yield variants with a highly increased activity. Gamma-radiation extended the variability but, at the same, substantially increased the number of non-producing and low-producing isolates. Relatively high yields of (+)-variants were obtained after treatment with nitrous acid but their activity did not reach that observed in the most active spontaneous variants.
Five commercial fertilizers, Amfos, ammonium sulfate, Kamex, Kieserit and NPK affected the transport of Escherichia coli, Pseudomonas aeruginosa and Salmonella infantis in sand columns. The percentage of cells transported through and without fertilizers during a 2-h period was species-dependent (0.56 for S. infantis, 3.1 for E. coli and 12.4 for P. aeruginosa). The cell transport was enhanced by Kamex for all strains tested, whereas Amfos was found to decrease the transport of E. coli and S. infantis cells. A mathematical model revealed a relationship between the transport of cells and the pH of the sand columns with fertilizers. Columns in which the pH was decreased by the fertilizers exhibited a higher retention of cells. This points to the existence of physico-chemical surface interactions between cells and sand particles.
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