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J C Ottow

Publications and source records attributed to J C Ottow.

At least 19 recordsLinked to original sources
PubMed1997

Degradation of the fungicide difenoconazole in a silt loam soil as affected by pretreatment and organic amendment.

Degradation of the fungicide difenoconazole was examined in a silt loam soil under controlled conditions (60% WHC, 30 degrees C) in the laboratory. Difenoconazole was applied at 0.1 and 1.0 mg kg(-1) dry soil, respectively. The experiments were run with non-pretreated and pretreated field soil, respectively, partly mixed with easily decomposable organic matter (leaf powder). In all experiments, degradation curves showed a sigmoidal shape with clear acclimation phases. Pretreatment with difenoconazole in the field decreased the acclimation phases, DT(50)- and, in some cases, DT(90)-values. The incorporation of easily decomposable organic matter decreased both DT(50)- and DT(90)-values and increased the general microbial activity significantly. We conclude that difenoconazole is metabolized by an acclimated part of the soil microflora. However, the degradation seems to be stimulated in the presence of suitable co-substrates.

Journal Article↗
PubMed1989

[Transformation of xenobiotics by soil microorganisms and their potential distribution].

Xenobiotics, i.e., unnaturally occurring organic substances, become transformed in soils, waters and ground water aquifers primarily by co-metabolism or by physico-chemical processes. The persistence of both xenobiotics and natural substances, i.e., time required for a 95% disappearance of the original compounds, is dependent on the chemical and physical characteristics of a compound itself (its molecular recalcitrance), on soil properties and conditions, and on the relationships of these factors. Among the specific factors which influence the persistence of individual compounds belong both natural and anthropogenic "non-physiological" characteristics and structures. Naturally occurring compounds become transformed metabolically, those with a xenobiotic character mainly co-metabolically. The degradation kinetics for both types of compounds have an exponential character, and according to a semi-logarithmic figure, it is a first order function (i.e., mineralization or transformation have a linear character). The co-metabolic processes depend closely on the concentration of the given compound in soil solution as well as on the general microbial activity. Metabolically utilizable compounds may serve microorganisms as sources of C, N, and eventually also of P and energy, after the necessary enzymes have become induced and synthetized. Co-metabolical compounds may not have these functions or microorganisms may require a long period to become adapted to them. In general, all means which support the microbial activity, may also support the co-metabolical transformations in the soil. This is especially true for aeration and manuring of soil both of which stimulate unspecifically the proliferation and activity of microorganisms, and indirectly also a co-metabolism of xenobiotics.

Bacteria↗
PubMed1982

Metabolism of the Plasticizer di-n-Butylphthalate by Pseudomonas pseudoalcaligenes Under Anaerobic Conditions, with Nitrate as the Only Electron Acceptor.

The metabolism of di-n-butylphthalate by a denitrifying strain of Pseudomonas pseudoalcaligenes B20b1 was studied under anaerobic conditions, with nitrate as the only electron acceptor. Thin-layer chromatography and mass spectral analysis of culture extracts (20 days at 30 degrees C) showed mono-n-butylphthalate and phthalic acid as the only products, suggesting that one butanol moiety served essentially as the carbon source for growth and denitrification. N(2) and N(2)O were detected by gas chromatography. In contrast to aerobic metabolism, phthalate was not degraded further if nitrate was the only electron acceptor.

Journal Article↗
PubMed1976

[On N2-fixing clostridia and bacilli from soils (author's transl)].

In total 30 nitrogen-fixing, saccharolytic Clostridia and 4 nitrogen-fixing bacilli, all freshly isolated from gleyed soils, were screened for sensitivity to 20 antibiotics. The isolates were compared in their sensitivity with 5 type cultures representing the species Clostridium butyricum, C. saccharobutyricum (2 strains) C. multifermentans and C. sporogenes. Generally speaking, both clostridia and bacilli are sensitive to the same antibiotics (Table 2). In addition, the nitrogen-fixing bacilli belonging to Bacillus polymyxa and B. macerans showed sensitivity to neomycin and kanamycin. Except for the species C. tyrobutyricum, none of the various saccharolytic Clostridium species could be distinguished by differences in sensitivity to antibiotics. Differential methods are given in Table 3.

Anaerobiosis↗