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J Kunert

Publications and source records attributed to J Kunert.

At least 37 records · Page 2Linked to original sources
PubMed1989

Growth of keratinolytic and non-keratinolytic fungi on human hairs. A physiological study.

Twenty-six keratinolytic fungi (16 dermatophytes and 10 soil species) and sixteen non-keratinolytic fungi were cultivated on sterile human hair in a mineral solution. With keratinolytic fungi, the loss in total dry weight (hair + mycelium) reached 7.6 up to 24.2% after 60 days of cultivation. Peptidic (Lowry-positive) substances accumulated in the medium and pH of the medium gradually increased, often over pH 8. Excess of sulfur contained in the substrate was excreted back into the medium predominantly in the form of inorganic sulfate. Moreover, sulfite was produced that cleaved disulfide bonds of the substrate giving rise to S-sulfocysteine; soluble products of keratin degradation in the medium contained 2.1 to 6.5% of that substance. This supports the presumption that sulfitolysis of disulfide bonds is a key reaction of keratinolysis in fungi. Statistically significant correlations were observed between substrate degradation and medium alkalinization, as well as the contents of peptidic substances, sulfate, and S-sulfocysteine. The correlation was highest with sulfate content and least significant with peptidic substances. Non-keratinolytic fungi mostly grew on the hair but did not cause a gravimetrically measurable loss of the substrate, did not alkalinize the medium, and did not accumulate the above mentioned substances in amounts comparable with those of keratinolytic species.

Child↗
PubMed1989

Utilization of L-cystine as a source of carbon and nitrogen by various fungi.

Thirty fungal species from various taxonomic and ecologic groups were cultivated on two glucose-peptone media enriched with cystine (3 mmol/l). Nineteen species showed certain ability to utilize cystine not only as a source of sulfur but that of carbon and nitrogen as well; six species utilized cystine completely. Excess sulfur was excreted after oxidation in the form of inorganic sulfate and/or sulfite back into the medium. Cystine metabolization was on average more rapid and complete on the medium with higher peptone content and better growth. When compared with keratinolytic fungi studied previously, the present set of fungi showed a lower tendency to cystine utilization and comprised species not utilizing this amino acid at all.

Carbon↗
PubMed1989

Antifungal effects of selenocystine and its derivatives on dermatophytes.

Antifungal effects of DL-selenocystine and its derivatives (DL-selenolanthionine, DL-Se-sulfoselenocysteine) and of sodium selenite were tested in 14 dermatophytes and 7 species of keratinolytic and non-keratinolytic soil fungi. Minimal inhibitory concentrations of the compounds were measured and compared to those of ketoconazole. Organic selenocompounds behaved similarly. They were on average less inhibitory than ketoconazole but, in some cases, MICs were equal or even lower. The effects of selenite were but small. The action of selenocystine and ketoconazole in concentrations up to 50 micrograms/ml was found to be mostly fungistatic. Free L-cystine (100 micrograms/ml) antagonized the antifungal effect of its selenoanalog.

Antifungal Agents↗
PubMed1988

Utilization of cystine by dermatophytes on glucose-peptone media.

All the 16 strains of dermatophytes tested here metabolized cystine (3 mmol/L) in two glucose-peptone media with a different C: N ratio. Cystine was utilized as a sulfur source and, in addition, as a carbon and nitrogen source, in parallel with growth. Excess sulfur was excreted to the medium after its oxidation as inorganic sulfate and sulfite. In a physiologically alkaline medium the growth was fast and was accompanied by a pH increase and cystine was utilized intensively. Eleven species used up all cystine available. Sulfate was the main oxidation product, sulfite was produced at a low concentration, at the beginning of growth in particular. Only traces of thiol compounds (cysteine) were present in the medium. In a physiologically acid medium growth was soon limited by a decreased pH (below 5.0) but cystine continued to be utilized at an identical rate. All cystine was used up by 5 species. The tendency to produce sulfite in addition to sulfate further increased and sulfite was often the predominant product. Concentrations of thiol compounds were also substantially higher. Thus, dermatophytes can utilize cystine even under conditions that do not support good growth and increase the sulfite production.

Arthrodermataceae↗
PubMed1988

Utilization of cystine by dermatophytes on a gelatin medium.

All 16 strains of dermatophytes investigated utilized cystine (added to the gelatin medium) as a source of sulfur and also of carbon and nitrogen. Excess sulfur oxidized and excreted to the medium, primarily as inorganic sulfate. Six strains used up all cystine and excreted more than 90% stoichiometric amount of sulfur. Cystine utilization proceeded in parallel with the development of the culture and was terminated during the stationary phase or as late as in the autolytic phase. Other strains did not use up cystine completely and excreted 17-70% sulfur in the oxidized form. In addition to sulfate, sulfite was always produced during the initial growth phases and in poorly growing strains. Free sulfite was only rarely detected; it usually reacted with the residual cystine yielding S-sulfocysteine that was also used up later. Specific features of cystine metabolism (known from Microsporum gypseum) are generally valid in dermatophytes.

Arthrodermataceae↗
PubMed1988

Preliminary characterization of extracellular proteolytic enzymes of dermatophytes by chromogenic substrates.

Thirty-eight chromogenic substrates were used to study the specificity of the proteolytic enzymes of seven species of dermatophytes and three related keratinolytic soil fungi. The source of enzymes were cultivation fluids from cultures of the fungi grown on human hair. The overall specificity of the enzymes of all the keratinolytic fungi was very similar. Aminoacyl- and dipeptidyl-4-nitroanilides, substrates of aminopeptidases and dipeptidyl aminopeptidases respectively, were poor substrates compared to aminoterminally blocked oligopeptidyl derivatives. Of the latter, the best substrates were those with phenylalanine, leucine, alanine, methionine or arginine (i.e. amino acids with hydrophobic or basic side chains) in the P1 position. Of the amino acids in the P2 position, proline was the most effective at accelerating the hydrolysis of the respective substrates. Positions P3 and P4 and even the aminoterminal protecting group were also of importance. The specificity profiles of the proteolytic enzymes corresponded best to those of some well characterized serine proteinases (chymotrypsin, elastase).

Arthrodermataceae↗
PubMed1987

Utilization of various concentrations of free cystine by the fungus Microsporum gypseum.

The dermatophyte Microsporum gypseum was cultivated on two liquid media enriched with 50 to 1000 micrograms/ml free L-cystine. The presence of cystine in concentrations above 250 micrograms/ml (gelatin medium) or 500 micrograms/ml (glucose-glutamate medium) inhibited the growth. In all variants, however, cystine was utilized from the very beginning of growth and exhausted completely until stationary phase. The rate of cystine metabolization grew with its concentration to 500 micrograms/ml but decreased again with 1000 micrograms/ml. The excess sulfur was oxidized and excreted back into the medium mainly as inorganic sulfate. Moreover, sulfite was also produced which immediately reacted with the residual cystine in the medium giving rise to S-sulfocysteine. Sulfite excretion was higher in the initial phases of growth and on the medium with poorer growth (gelatin medium). The sulfate-to-sulfite ratio was different on the two media used but was little influenced by cystine concentration. The excretion of strongly acidic compounds (sulfate, sulfite, and S-sulfocysteine) reduced the usual alkalinization of the medium in the course of growth.

Culture Media↗
PubMed1987

On variance estimation in crossover designs.

It is very unlikely that the errors in crossover experiments with more than two treatments are uncorrelated. The assumption of uncorrelated errors generally leads to underestimation of the variances of estimates. This paper determines bounds for the degree of underestimation for arbitrary covariance matrices, provided the experiment is planned according to a design that has the same numbers of periods and treatments and is balanced for carryover effects.

Analysis of Variance↗
PubMed1986

Cystine catabolism in mycelia of Microsporum gypseum, a dermatophytic fungus.

The fate of 35S label was studied during cystine degradation by mycelia of the dermatophytic fungus Microsporum gypseum. Excess free cystine in the medium was readily taken up and its sulfur moiety excreted as inorganic sulfate and sulfite. At intervals after 3-60 min of incubation with 35S cystine the products of cystine catabolism were extracted from the mycelia by boiling water and separated by thin layer chromatography and electrophoresis. A total of 10 sulfur-containing compounds were identified, and their relative radioactivity was assessed. After 3 min the mycelia contained, in addition to cystine, labeled cysteine and particularly cysteine sulfinic acid which was accompanied by a smaller amount of cysteic acid. Later on, oxidized and reduced glutathione, inorganic sulfate and taurine appeared consecutively. In all extracts, small amounts of labeled S-sulfocysteine were found, not, however, sulfite. The results suggest that the intermediates of cysteine degradation in the fungal mycelia are cysteine, cysteine sulfinate, unstable sulfinylpyruvate, sulfite and sulfate, i.e., that the catabolic pattern is similar to that of higher organisms. The formation and the role of S-sulfocysteine, cysteic acid, and of taurine is not yet completely understood, although certainly autoxidative processes are involved in the formation of the latter two compounds, and sulfitolysis in that of the former compound.

Chromatography, Paper↗
PubMed1985

Metabolism of sulfur-containing amino acids in the dermatophyte Microsporum gypseum. I. Neutral amino acids.

The dermatophyte Microsporum gypseum was cultivated on a glucose-arginine medium to which on out of six sulfur-containing amino acids was added (L-cystine, L-djenkolic acid, DL-lanthionine DL-homocystine, L-methionine, or L-methionine-sulfone at a concentration of 5 mM with respect to sulfur content). The addition of these substances did not stimulate the growth and some amino acids (djenkolic acid and particularly methionine and methionine-sulfone) were inhibitory. All tested compounds were utilized during the growth not only as sulfur source but as a source of carbon and nitrogen as well. In four substrates excess sulfur was excreted after oxidation into the medium in the form of sulfate. Small amounts of sulfite were also observed. It usually reacted with remaining disulfides in the medium forming S-sulfo compounds (R-S.SO3H). Cystine and djenkolic acid were oxidized rapidly and completely. In contrast, lanthionine and particularly homocystine were oxidized slowly and only after a longer adaptation. To some extent lanthionine was already oxidized extracellularly in the medium. With methionine and its sulfone, excess sulfur was not removed by oxidation but by demethiolation to methane thiol and further volatile products.

Alanine↗
PubMed1985

Metabolism of sulfur-containing amino acids in the dermatophyte Microsporum gypseum. II. Acidic amino acid derivatives.

The dermatophyte Microsporum gypseum was cultivated on a glucose-arginine medium supplemented with five strongly acidic derivatives of cysteine (L-cysteine sulfinic acid, L-cysteic acid, L-serine-O-sulfate and taurine at a concentration of 5 mmol/l, and L-S-sulfocysteine at a concentration of 2.5 mmol/l). The addition of these substances did not stimulate the growth as compared with the control containing 0.5 mmol/l cystine. Cysteine sulfinic acid and cysteic acid showed rather inhibitory effects. A strong inhibition of the growth was caused by the presence of serine sulfate. During the growth, all substances investigated were gradually consumed and utilized not only as a source of sulfur but of nitrogen and carbon as well. Cysteine sulfinic acid and S-sulfocysteine were utilized most rapidly. Cysteic acid was also rapidly utilized but after a certain adaptation. Taurine was utilized slowly and serine sulfate very slowly. Excess sulfur contained in the substances used was excreted into the medium in the form of sulfate. Sulfate excretion was most rapid with cysteine sulfinic acid and slowest with taurine. With cysteine sulfinic acid, S-sulfocysteine and cysteic acid, small amounts of sulfite were found in the medium. The results obtained are in accordance with the presumption that cysteine sulfinic acid (but not cysteic acid and taurine) is an intermediate of cysteine catabolism in dermatophytes.

Amino Acids, Sulfur↗
PubMed1983

[Cytokeratin].

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Animals↗
PubMed1982

Utilization of L- and DL-cystine by the fungus Microsporum gypseum.

Growth of the fungus Microsporum gypseum and utilization of cystine during this growth was studied in a glucose-arginine medium containing either sodium sulphate, and L-cystine or DL-cystine. Replacement of sulphate with L-cystine brought about no significant changes in the growth of the microorganism. Utilization of L-cystine as a source of carbon and nitrogen was rapid and complete and excess sulphur was excreted into the medium in the form of sulphate. Similarly excreted were also minute amounts of sulphite which immediately reacted with the remaining cystine to form S. sulphocysteine. Growth of M. gypseum in a medium with DL-cystine was slow. Although this substance was not utilized as readily as L-cystine, its utilization was still complete and excess sulphur was similarly excreted in the form of sulphate and sulphite. The initial step in the utilization of the D-isomer is probably its extracellular deamination.

Culture Media↗