Mutagenicity of antiviral substances of nucleobase analogue type in Salmonella typhimurium employing metabolic activation by mouse liver homogenate or cell-free plant extracts.

Five nucleobase analogues with antiviral properties were tested for their mutagenic activity in his mutant strains TA 1535, TA 1537, TA 1538, TA98, and TA 100 of S. typhimurium by means of preincubation tests with and without metabolic activation by cell free fractions from mouse liver (S-9) and maize seedlings (S-14). In one bacterial strain 6-azathymine increased the revertant counts in the absence of metabolic activation systems. In the presence of S-9 mix, the same substance became mutagenic for another tester strain. Metabolic activation by S-14 resulted in weak mutagenicity of 5-azadihydrouracil in high concentrations. 6-Azauracil, 5-azauracil, and 5-azadihydro-1,3-diacetyluracil were without mutagenic activity in all Salmonella-strains used. Cyclophosphamide, like other standard promutagens, was shown to become mutagenic in the presence of S-14 plant fraction. Thus S-14 activation system besides the S-9 liver system can be employed in mutagenicity testing with microbial systems.

Mutagenicity assay with Salmonella typhimurium revealing biotransformation of antiphytoviral substances by cell-free plant extract.

The mutagenic activity of four antiphytoviral substances was tested in reversion mutagenicity assays with a set of histidine auxotrophic strains of Salmonella typhimurium by means of the preincubation method. A possible metabolic activation of the substances by cell free fractions from maize seedlings (S-14-fraction) and for comparison from mouse liver (S-9 mix) was examined. None of the guanidine, phenyl urea and thiadiazole compounds exerted mutagenic activity in the bacterial strains in experiments without metabolic activation. Cyanoguanidine and N-phenyl-N-carboxyphenylurea became mutagenic for Salmonella strain TA98 after metabolic activation by the S-14 plant fraction. Both substances were not mutagenic in the presence of S-9 mix made from mouse liver. The promutagen cyclophosphamide proved highly mutagenic in experiments with S-14 mediated plant metabolic activation. This kind of bacterial mutagenicity assay is valuable in investigations of potential agrochemicals, as the examples have shown.

[Degradation and utilization of 2,4-dioxohexahydro-1,3,5-triazine (DHT) by soil microorganisms]. / Abbau und Verwertung von 2,4-Dioxohexahydro-1,3,5-triazin (DHT) durch Bodenmikroorganismen.

The biodegradation and utilization of the antiphytoviral substance 2,4-dioxohexahydro-1,3,5-triazine (DHT) by soil microorganisms was investigated. Mixed cultures of microorganisms deriving from different soils diminish in nutrient broth the content of DHT with increasing duration of culture. Microorganisms from an Egyptian garden soil fully degrade 10(-3) mol/1 DHT in a culture without additional aeration within 28 days. Also in deficient media the mixed microorganisms reduce the amount of DHT, reaching in nitrogen free nutrient solution even a degradation rate up to 12 mg DHT per liter and day. Pure cultures of Rhizobium leguminosarum, Proteus vulgaris, Saccharomyces cerevisiae and especially Agrobacterium radiobacter diminish the content of DHT in nitrogen free media, too. No such effect was detectable in cultures of four other species of soil bacteria. The DHT degradation by the microorganisms is connected with significant cell multiplication, e.g. A. radiobacter in shaking cultures with DHT as sole source of nitrogen shows a typical growth cycle with a lag-phase of 24 hours. The short persistence time of DHT in soils is concluded to be mainly due to biodegradation by microorganisms.

[AS-1L - a newly discovered strain of Cyanophage AS-1 in GDR]. / AS-1L - ein neuer, in der DDR aufgefundener Stamm des Cyanophagen AS-1.

In samples, taken from waters in the surroundings of Leipzig (GDR) in 1978, we found cyanophages in Central Europe for the first time. Among other cyanophages we isolated the new strain AS-1L. Out of 20 tested cultures of unicellular cyanobacteria seven strains belonging to the genus Synechococcus proved to be susceptible for this cyanophage. In morphology AS-1L corresponds to the cyanophage AS-1 found in the U.S.A., to which it is related serologically, too. AS-1L differs from the other strains of AS-1 by a shorter growth cycle, especially a shorter latent period, by the kinetics of inactivation by antiserum, and by a somewhat narrower pH scope of stability. Consequently the isolated cyanophage is to be looked at as a new strain of the cyanophage AS-1.

[Effect of the detergent Metaupon on replication of various phages]. / Wirkung des Detergens Metaupon auf die Vermehrung verschiedener Phagen.

As several other surfactants do, the detergent Metaupon acts on the multiplication of bacteriophages. We investigated the influence of Metaupon on the phages phi and lambda, the cyanophage LPP-1, and the RNA-phages f 2, M 12, and Q beta by means of the agar diffusion test, pour plate test, adsorption test, and one-step growth test. The action of Metaupon on the free phages was also tested. Metaupon inhibits the formation of plaques by the phages with exception of lambda. With the phages f 2 and M 12 the substance increases the amount of plaques depending on concentration. The main mode of action of Metaupon was found to be the inhibition of the adsorption of the phages to the host cells. Only in the case of phi 105 free phages were inactivated.

[Effect of 1,3,5-triazines on various bacteriophages and their hosts]. / Wirkung von 1,3,5-Triazinen auf verschiedene Prokaryontenviren und ihre Wirte.

In the agar diffusion test 24 triazines were investigated with regard to their action on the mulplication of DNA phages (lambda and LPP-1) and RNA phages (M12 and Qbeta). In several cases the amount of plaques was diminished or increased depending on the kind of triazine and virus. The investigations demonstrate the triazines to be able to interfere with the formation of plaques by virulent and temperate viruses of procaryotes.

[The action of selected herbicides on bacteriophages and Escherichia coli (author's transl)]. / Der Einfluss ausgewählter Herbizide auf Bakteriophagen und Escherichia coli.

The effect of eight herbicides on the multiplication of bacteria and bacteriophages was tested with Escherichia coli, strains W1665F+ and C600, and with the RNA-phage M12 and the DNA-phage lambda in turbidimetric investigations and one-step growth experiments. E. coli is inhibited by seven of the herbicides investigated in concentrations of 10(-3)M, partly of 10(-4)M, too, and is promoted by some compounds in weaker concentrations. Naphthylacetic acid, (NES) largely independent of its concentration, causes increased density of bacteria in fluid culture. The multiplication of the M12 phage is inhibited in sometimes wide ranges of concentration by 2,4-D, MCPA, 2,4-DP, and CMPP but it is stimulated by NES and amitrole. The lambda-phage multiplication is inhibited only by CMPP, MCPA, MCPB, and phenylacetic acid interfere with the lysogenization of the bacteria and increase the lytic activity of the lambda-phages as 2,4-DP and NES do. 2,4-D strongly inhibits the plaque-forming ability of M12 phages already prior to their contact with the host cells, whereas MCPA and CMPP are inhibitory in the first phases and 2,4-DP in all phases of the phage replication. In the lambda-phage replication, too, CMPP is effective only in the first phases. Aspects of the mode of action of the herbicides in the procaryoute virus system are discussed.

[Effect of several plant growth regulators on various prokaryotes and their viruses]. / Wirkung von einigen Pflanzenwachstumsregulatoren auf verschiedene Prokaryonten und deren Viren

26 plant growth regulators including herbicides were investigated in their effect on the multiplication of Escherichia coli, Bacillus subtilis, and the blue-green alga Plectonema boryanum as well as the RNA phages M 12 and Qbeta and the DNA phages lambda, phi 105, and LPP-1 employing the agar diffusion method. Nearly all of the compounds inhibited and/or stimulated one or some of the prokaryotes tested. The most frequent and strongest effects occurred in Pl. boryanum, the least effects in E. coli. The multiplication of phages was also influenced by plant growth regulators leading to increase, decrease or non-appearance of plaques. The investigations with the temperate phages lambda and phi 105 suggested part of the compounds to be able to interfere with the process of lysogenization. The results are discussed comparatively involving correspondent findings referred to in literature.