Biomedical subjects

J Rybárová

Publications and source records attributed to J Rybárová.

7 recordsLinked to original sources

PubMed1984

Mineralization of 2,4-dichlorophenoxyacetic acid in soil simultaneously enriched with saccharides.

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 of 14CO2, a product of microbial degradation of 2-14C-2-4-D, was measured during 38-d incubation at 28 degrees 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 into 14CO2). 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.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1984

Mineralization of 2,4-dichlorophenoxyacetic acid in soil previously enriched with organic substrates.

Samples of chernozem soil were enriched with vanillic acid, protocatechuic acid glucose, a mixture of glucose and (NH4)2SO4 (C : N = 5 : 1), ethanol and 2,4-dichlorophenoxyacetic acid (2,4-D). After a 6-d (with 2,4-D 35-d) incubation during which primary oxidation of the introduced substrates occurred, the soil was supplied with a solution of 2-14C-2,4-D (50 ppm; 6.7 kBq) and production of 14CO2 (product of microbial degradation of 2,4-D) was measured. Previously enriched samples exhibited a higher degradation rate; both the lag phase and doubling time of mineralization activity in the exponential phase of the process were markedly higher. This reflected an overall proliferation of bacteria and the increased relative proportion of bacterial strains capable of mineralizing 2,4-D in enriched samples. The stimulation of 2,4-D degradation may involve specific adaptation and selection mechanisms (as in the case with samples previously enriched with 2,4-D or its structural analogues--aromatic monomers, ethanol) as well as non-specific mechanisms. The extent of mineralization of 2,4-D was not affected by soil pretreatment, about 1/3 of introduced radioactive carbon being invariably transformed to 14CO2.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1984

[Overview of the allergens from several feeder regions of Czechoslovakia. Incidence and prevalence of contact hypersensitivity caused by the allergens spread by the population of the feeder areas of Bratislava, Trnava and Banská Bystrica 1978-1980].

With the aid of patch tests an investigation involving 3060 patients was carried out to register the incidence and prevalence of allergens of the standard and supplementary test series. The standard series with 16 allergens was selected in cooperation with the work group for curtailing contact dermatitis and occupational dermatoses in the socialist countries. The Czechoslovakian supplementary test series included three allergens: neomycin sulfate, extr . chamomillae and resorcinol. In 22.6% of the 693 patients the skin tests were positive for at least one allergen. The most frequent eczematogenic among men was potassium dichromate (resulting from contact with cement), among women nickel sulfate, and in the group as a whole Peruvian balm. The age groups most affected were between 41 and 50 years and between 51 and 60 years, respectively, for men, between 21 and 30 years for women, and between 21 and 30 years for the group as a whole. In registering the prevalence, chamomillae extract caused the highest occurrence among men, cobalt nitrate among the women, and also cobalt nitrate for the group as a whole. The age group affected most was between 51 and 60 years. In the complete investigative study of incidence and prevalence, Peruvian balm topped the list for the group as a whole, potassium dichromate for the men, and nickel sulfate for the women. Among the men and for the group as a whole the most affected age group was between 51 and 60 years, and among the women between 21 and 30 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1983

Effect of glucose on the amount of bacteria mineralizing 2,4-dichlorophenoxyacetic acid in soil.

Plate numbers of bacteria and relative incidence of strains capable of mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) in chernozem samples incubated for 14d with the herbicide (50 ppm) in the presence or absence of glucose (1000 ppm) were compared. Whereas the total number of bacteria increased 1.2-fold in the variant with 2,4-D and 2.4-fold in the variant with glucose and the herbicide, the number of 2,4-D-mineralizing bacteria increased 12.1-fold and 34.2-fold, respectively. In a collection of 96 isolates of soil bacteria substantially more strains capable of degradation of 2,4-D in the presence of glucose were detected as compared with the variant without it, indicating that processes of cometabolic type are involved during the degradation of this herbicide in the soil.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1981

Torulopsis ethanolitolerans n. sp. and T. ethanolitolerans var. minor n. var.

A new yeast, Torulopsis ethanolitolerans and its variety minor, both isolated from industrial sulphite fodder yeast cultivated on synthetic ethanol as the only source of carbon, originally designated R 5, R 6 and the variety R 7, are described. This species differs from all recently accepted Torulopsis species (resp., Candida species), which do not assimilate nitrate, not ferment any sugars, not produce urease, by the assimilation of maltose, but not of sucrose, lactose and D-xylose.

Candida↗

PubMed1980

Candida ethanolica n. sp.

A new yeast, Candida ethanolica, isolated from industrial fodder yeast cultivated on synthetic ethanol as the only source of carbon, originally designated III-5 and III-6, is described. This species differs from all recently accepted Candida species in not assimilating nitrate, not producing urease and not fermenting sugars.

Candida↗

PubMed1977

Microbial activity in soil enriched with preparations of AS-lignin and lignofulvonic acid.

In chernozem soil, enriched with preparations of AS-lignin or lignofulvonic acid, an increased production of carbon dioxide was observed during a 4-week incubation, and, as compared with the non-amended control, an increased number of bacteria but not of actinomycetes was detected. Increased numbers of fungi were detected only in the variant with AS-lignin at the end of the incubation. The relative incidence of bacteria utilizing vanillin, syringic acid or protocatechuic acid as the only carbon sources increased in the enriched medium. Oxidation of vanillic acid, syringic acid and to a lesser extent of coumarin increased in suspensions of soils incubated with AS-lignin or fulvic acid. The results obtained indicate that bacteria are involved in the mineralization of the added substrates and confirm the relationship between metabolism of these compounds and simple aromatic derivatives.

Actinomycetaceae↗